Building a narrow gauge locomotive on 5" Gauge.....2 1/2" scale. By John Richardson

Based on the construction of my scratchbuilt model of Kerr Stuart loco ' Pixie 'Surveyed at Leighton Buzzard NG Railway.

For illustrations and brief description of construction see the page ' Building the locomotive PIXIE on 5" Gauge ' at pixiesbackground.htm

PIXIE

FOREWORD by Mr Ted Jolliffe, Editor of the Magazine ' MODEL ENGINEER '

INTRODUCTION by the author

The attractions of model engineering, locomotives and narrow-gauge in particular. An outline of the approach to model engineering in the book.

CHAPTER CONTENTS

Ch. 1 Choice of prototype. Space, weight and scale considerations. Location of track. Haulage and handling considerations.

Ch. 2 Establishing detail. Research. Manufacturers drawings. Commercially available designs. Value of the model press, exhibitions and club membership.

Ch. 3 Going it alone. Surveying a prototype. Equipment for the survey. A system of working. Ongoing visits. The database. Use of photographs, transparencies and prints.

Ch. 4 Workshop, tools and equipment. Practical aspects of heating, lighting and ventilation. Workshop practice for the model engineer. The logbook.

Ch. 5 Materials. Sources of supply. Organised storage and the scrap box. Modifying available materials. An introduction to simple pattern making.

Ch. 6 Planning. Model engineering with pencil and paper. Machining sequence. Fabrication vs. castings. Use of models, mock-ups, jigs and templates.

Ch. 7 Frames, stretchers, horns and axleboxes. Wheels, axles, crankpins and quartering.

Ch. 8 Coupling rods and bearings. Brake hangers and blocks. Lubricator and mounting plate. Coupling blocks. Footplates, support brackets and angles.

Ch. 9 Patterns and castings. Smokebox saddle. Cylinders, ports, passages, covers and glands. Pistons and piston rods.

Ch. 10 Motion work. Motion plate. slide bars and crossheads. Valve gear, weigh shaft and reversing gear. Valve setting. Brake standard.

Ch. 11 Smokebox and and smokebox door, hinges and rings. Wet header, steam, blast and petticoat pipes. Blower ring.

Ch. 12 Boilers. Home built vs proprietary supply. Construction techniques. Location. Firehole door. Cleading.

Ch. 13 Pumps. pipework, valves and gauges. Sandboxes and gear. Clacks and dummy injectors.

Ch. 14 Fittings. Regulator, regulator gland and lever. Chimney. Steam Dome. Safety valves. Retro-fitted pump eccentric. Cylinder drain cocks.

Ch. 15 Platework, tanks and bunkers. Saddle tank. Weather board/spectacle plate. Roofs and backs. Footplates. Ashpan. Cutting, bending and riveting plates.

Ch. 16 Erection, smokebox, boiler, reversing lever, regulator, steam and exhaust pipes. Pumps. Platework. Makers plates.

Ch. 17 Painting. Workplace and equipment. Types of paint. Preparation.

Ch. 18 Test track and a simple driving trolley. Materials. Driving position and access to controls. Braking.

Ch. 19 Steaming the locomotive. A simple blower. Raising steam and driving. Safety aspects.

Ch. 20 Some useful tools and attachments from materials in the scrapbox.

Ch. 21 Conclusion and model engineers nostrums (? nostra)

FOREWORD

( This was written when the book was first published on 2 Floppy disks !.....John )

I have, over the last few years, had the pleasure of watching Pixie grow, from a design concept through to a finished locomotive. this has been thanks to occasional personal contact, and largely through the occasional articles submitted to MODEL ENGINEER magazine detailing progress to the latest stage.The author is a meticulous craftsman, with a well developed and organised workshop, each feature being installed as a result of considerable thought. That he has chosen to set out this account of his activities, revealing both the triumphs and difficulties encountered in the construction, is a tribute to his meticulous recording of his work.

Of all the books that I have read concerning the building of small locomotives, this one adopts a novel approach, taking as a starting point the actual workroom or other premises which are to be used for the work. Very often this is a facet of locomotive building which is neglected; leading to considerable problems later.

I like the attention to detail, the account of the research needed to bring the product to fruition, the novel approach to pattern making, and the authors somewhat novel approach to gleaning much of the material needed.This is a very readable account of the building of a well detailed locomotive and, as importantly, the many hints and tips of a practical nature passed for the benefit of other constructors by the author.

One can only applaud his industry in making the volume available in this fashion, I for one wish the volume every success.

Ted Jolliffe. Editor

Model Engineer Magazine. Hemel Hempstead. 2nd November 1994

 

Preparing PIXIE for transport to the Model Engineering Exhibition

Chapter 1

CHOICE OF PROTOTYPE

WHY NARROW GAUGE?

Choice of prototype. Space, weight and scale considerations. Location of track. Haulage and handling considerations.

Narrow gauge locomotives and rolling stock, as we in the United Kingdom know them, have a flavour of their own, quite removed from the nature of those of standard gauge railways. Historically narrow gauge lines, essentially light railways, have been quaint and often slow moving yet, in their own way efficient servants of the community. They and their dedicated staff have traditionally provided a personal, if somewhat erratic service, perhaps running in fits and starts, sometimes even stopping for an individual passenger at a field gate. History also records instances where the traveller has been required to assist in re-railing a piece of stock or in fetching water for the boiler!

Narrow gauge lines have a history of running on uneven, occasionally weed overgrown track. They take acute bends and steep gradients in their stride, rarely travelling at speeds exceeding 20 m.p.h. The locomotives are picturesque, often of short wheelbase, sometimes with with small boilers, tall chimneys, intricate weather plates and other interesting items of equipment. In some instances narrow gauge locomotives are festooned with 'Victoriana' in the form of sandpots, polished plumbing and literally all manner of bells and whistles. Having said all that, we have to remember that on most continents there are narrow gauge (narrower than standard gauge that is) locomotives working over hundreds of miles of mountainous and inhospitable countryside. Such for example are the metre gauge railways of India and Malaya, and the South African and Ecuadorian Railways of 3 foot 6 inch gauge. In this book we concern ourselves with the narrower gauges and the smaller locomotives which have come to regarded in this country as the 'Norm' for narrow gauge.

There is a wide range of prototypes from which to make a selection. Firstly there are the conventional locomotives, often carrying out the duties of standard gauge locomotives over difficult terrain. Then there are tram locomotives, which worked in the industrial or urban environment, many of these are notable for their shrouded wheels and motion and controlled emissions of smoke and steam. They would be designed to be controlled from each end of the footplate, also hand and steam brakes would be compulsory. A number of tram locomotives were built with vertical boilers, an added touch of interest in model form. Vertical boilered locomotive models provide the builder with an opportunity to incorporate some previously built essay in model engineering, such as a Stuart Turner engine into their model. De Winton locomotives with vertical boilers and cylinders were virtually an engine platform with water tank, bunkers, reversing lever and brake standard. Inside and outside frame configurations were employed, also inside and outside drive, the latter by lay shaft and crank. R.A.S Abbot in his book on the topic describes how some locomotives carried the chimney directly above the boiler to avoid the formation of condensation and some locomotives were fired by sliding the fuel down chutes into the firebox located between the frames, plenty of scope here for the freelance modelmaker ! In an article in MODEL ENGINEER Vol 163 No.3859 October 1989, Phil Atkinson gave the reader food for thought in his description of ' Coffee pot locomotives ' outshopped from Head Wrightsons Works in the late 1800's, with their heavily riveted vertical boilers and substantial wheelsets, these little locomotives would present a challenge, and a reward for the builder. A surprising feature of the locomtive was a one piece, cast iron frame incorporating main side members, buffer beams, the fuel bunker, all foot plates and the stiffening ribs, the whole described by Phil as a fine piece of the Victorian designers, pattern makers and iron founders art. No. 16 by the same builder even sports a rudimentary roof although one which would afford little protection to the driver !

For added spice, builders may turn their attention to innovative locomotives such as LOCOMOTIVE NO. 1 of the Listowel & Ballybunnion Railway, straddling an early monorail. Double-bogied types such as those of the Festiniog Railway would present a challenge, or perhaps the modeller would wish to undertake a model of one of the the SHAYS or HEISLERS of the American short lines scene. Ken Swan's series on 'KOPPEL' a rack locomotive in ENGINEERING IN MINIATURE could prompt the modeller to produce, for instance, a model of Locomotive Number 7 on the Snowdon Mountain Railway, although track construction would present a major challenge. Those seeking a simpler prototype would do well to build the locomotive Ross Harrison described commencing in ENGINEERING in MINIATURE, issue of September 1982, a convincing model in 5" gauge based upon 'EDWARD THOMAS', Kerr Stuart 'Tattoo' Class locomotive built in 1921 for the Corris Railway, later moved to the the Talyllin Railway, a model full of atmosphere.

For something really different the modeller might turn to the locomotives of a Dublin Brewery, designed by Samuel Geoghegan. These 1 foot 10 inch gauge locomotives with cylinders and motion placed ABOVE the boiler were used in conjunction with haulage trucks into which they were hoisted for working the 5 foot 3 inch gauge. In this role the wheels of the locomotive rested on grooved rollers which propelled the trucks. Contractors locomotives make interesting prototypes and many model engineers have built 'SWEET PEA', designed along these lines by Jack Buckler. Some of these models exhibit remarkable modifications and there is scope for innovation. This locomotive would make an ideal test-bed for the model engineer who likes to experiment with features of his own design. Contractors locomotives provide a range of prototypes suited to modelling and it is a salutary thought that narrow gauge locomotives such as the Bagnall locomotive 'EXCELSIOR', a delightful little 0-4-0, were employed in much industrial construction as well as civil engineering works for railways.

A series of articles by Martin Evans in MODEL ENGINEER commencing in 1980 described a free lance narrow gauge 0-4-0 Saddle Tank Locomotive, 'CONWAY'. This again was a blow-by-blow description and, as with all Martin Evans designs, examples of the completed model have been seen performing credibly on a many occasions.

The modeller fortunate enough to locate the Armley Industrial Museum in Leeds can find there the beautifully preserved Hunslett narrow gauge locomotive 'JACK', resplendent in scarlet livery, lined in yellow and black. Built in 1898 for employment in a fireclay works near Burton-on Trent, 'JACK' is outside framed, has Baguley valve gear and masses of brass and copper in the steam dome and plumbing, with brass lubricators mounted on the smokebox. On top of the boiler are twin sand boxes and the loco has some nice details such as the hinged lights on the weather board and the drain pipes from the cylinders passing through the front beam. Running like a Rolls Royce it is a wonderful sight and one to make any model engineers pulse skip a beat. 'JACK' featured on the cover of MODEL ENGINEER Vol 158, No. 3798 April 1987 and a description of the locomotive appeared in that journal of October 1984

Lest it be thought that narrow gauge locomotives are mainly of simple design there are many examples way and beyond 0-4-0 configuration as regards complexity. These will present just as much of a challenge as a standard gauge locomotive. For example there are the Manning Wardle & Co. 2-6-2 side tank locomotives and the 2-4-2, Baldwin, 'LYN' of the Lynton and Barnstaple Railway. ('LEW' of this railway is, at the time of writing, being described in a construction series for 3 1/2 inch gauge in ENGINEERING IN MINIATURE.) For the really adventurous constructor there are of course the 2-6-2 + 2-6-2 Garrats of the South African and Indian railways.

Decisions, decisions....!

The writer's decision to model PIXIE the Kerr Stuart ' Wren' Class locomotive KS4260 / 1922 was based upon several factors. First and foremost was the impression that the sight of the little locomotive as it coasted into Pages Park Station on the Leighton Buzzard Narrow Gauge Railway one spring afternoon. It seemed incredible that a locomotive, produced initially for work on the installation of a sewer in 1922, should 60 years later be found running like a Rolls-Royce and doing useful work in a domestic setting. Enquiries revealed a little of the history of the locomotive, the fact that after the completion of the Barkingside sewer contract it had for some years worked in the Wilmington Road Quarry of Devon County Council, eventually being purchased by the Industrial Locomotive Society and brought to Leighton Buzzard in the late 1960's. The locomotive has an overall length of something over 10 feet, it weighs 3 Tons 7 cwt empty, and 4 tons 3 cwt in working order. The inside framed locomotive has Hackworth valve gear and is resplendent in an attractive livery of black, green and gold.

Here was a locomotive that was mechanically quite simple for a relative beginner to construct, It would be accessible for survey and was in the hands of friendly folk who were prepared to assist with provision of information. The railway was within 25 miles of home base, so that the survey could be staged over a series of visits. Above all, the locomotive had an atmosphere and charm which appeared to the writer to convey the very essence of narrow gauge railways. The decision has never been regretted and has, over the past ten years, opened up a whole new interest in the mechanical engineering of railways and of narrow gauge railways in particular.

At this stage the modeller intending to work in narrow gauge has to come to terms with the fact that just as much work will be involved in producing his chosen model as in producing one to run on standard gauge. Pixie was ten years in the building, through choice. Some things are too good to hurry and although one is always keen to get one's first locomotive onto the track, later efforts can be savoured, and perhaps greater attention paid to detail. In some instances such as for instance if a decision was made to model 'MERDDYN EMRYS', of Festiniog Railway fame, far more work could be involved. There could however be a saving in unit time in producing duplicate equipment, motion, tanks etc. In practice some builders do make locomotives in pairs and professionals make batches for just this reason.

SIZE

Although construction of a sizeable standard gauge model locomotive may make excessive demands on the capacity of one's workshop and equipment, narrow gauge locomotives are generally simpler in design and, at the same scale, work up smaller in model form. ( This fact can be used to advantage by the modeller 'moving-up' to a larger scale). The flavour of work and operations on a narrow gauge line can be replicated within a small workshop and in ones own backyard. Model engineering activities along narrow gauge lines' provide every opportunity for the incorporation into models of the very things that attract us to the prototype, to make and handle the artifacts that would otherwise, unless one works as a volunteer on a preserved line, be literally beyond reach. It should be remembered however that modelled on 5" Gauge quite a small locomotive such as PIXIE, at some 10 feet overall, will be more than 25" long in model form and of such dry weight that it is beyond one (normal) man's lifting ability! Quite apart from the weight of the model the physical size, 25" long x 11.5" wide by 20" high are dimensions to be reckoned with when it comes to handling in the workshop and between shop and track! These details will not daunt the enthusiast however and ways and means are discussed later in this book.

SCALE CONSIDERATIONS

There are many factors to be considered when deciding upon the scale in which to model the chosen prototype. Whilst often one reads a statement that ' such and such a scale was chosen because of the equipment available on which to machine the parts' there is a lot more to be taken into consideration! Even a model of a small locomotive like PIXIE requires space for storage, maneuvering from storage to the track and general handling for maintenance and overhaul. In the case of Pixie it became necessary to build the hoist detailed in chapter xxx to carry out these simple exercises in comfort!

One can comfortably carry out the machining operations for a 5" Gauge narrow gauge locomotive on a lathe in the Myford, ' maid of all work' series, or some similar equipment. In case of need, one can often obtain assistance with larger components from a local engineering works or by enrolling at a local Evening Institute. Many trojans work on 7 1/4" Gauge although here the parts, particularly the boiler assume relatively massive proportions. The enthusiast will tell you that these aspects are offset by the ride-in capability of their models and one can see their point of view. Access to a suitable track for running a 7 1/4" locomotive is however likely to be beyond the reach of many people, depending of course upon geographical location. On the other hand, 3 1/2" and 5" Gauge tracks are generally accessible, the local club probably offers both facilities and one will not require a pantechnicon to get the locomotive there. 3 1/2" gauge locomotives will fit easily into the family car as will some 5" gauge models, although larger locomotives on this gauge may require a purpose-made trailer. Narrow gauge locos for 5" track can be loaded into an estate car, and at a pinch can be manhandled by two strong men. Models scaled to 5" gauge offer sturdiness of components capable of surviving such rigorous handling. There are numerous designs and details available. Over the years, blow by blow descriptions of the construction of such models have appeared in the model press. Narrow gauge on 3 1/2" track can be ideal for a garden railway but for ride-behind fun the larger gauge has more to offer. In the case of a model such as Pixie, 2 1/2" to the foot scale on 5" gauge provides a stable ride, with a locomotive that has heft, and parts that are definitely out of the 'watchmaking' class! At this scale too the locomotive is robust, the firehole door whilst small provides a reasonable target for firing on the move and the levers and valves are sufficiently large to convey the feeling of the real thing in use.

TRACK LOCATION

Of course the ideal track location must be around one's own garden. Few of us however, are fortunate enough to have sufficient space at our disposal, particularly for anything other than an out-and-back track. Having said that, the out-and-back track has its merits. It can be simple, relatively cheap to construct and lay, as well as providing a useful test facility. Whilst it would be grand to have a railway sweeping round the grounds, there is a lot to be said for 50' or so of portable track that can be laid down on the lawn or the terrace when required. Such a track avoids problems with landscaping and garden maintenance such as weeding and grass cutting. When the urge to steam a locomotive arises it is a simple matter to fetch the lengths of track from the shed or garage, lay them down, fasten a few fishplates, and be ready to run. One length of such track, carried into the workshop, will prove useful when setting valves and carrying out routine maintenance. Construction of a suitable track system is described and illustrated in a later Chapter.

The more fortunate may have space available which will permit a complete circuit, with perhaps a siding into a storage shed. This is not beyond the bounds of a medium sized backyard and one hears of 0-4-0 locomotives happily negotiating 6 foot radius curves although it has to be said that the larger the radius the better. Certainly a small engine shed could be made to look most attractive and its location on the running ground would avoid a lot of effort that otherwise has to be expended in handling between steamings.

HAULAGE AND HANDLING CONSIDERATIONS

Where there is sufficient space it is convenient to store the locomotive in the workshop. Failing this, perhaps a corner of the garden shed or garage can be set aside. It will prove helpful if the loco can be kept stored on a small trolley, Pixie's trolley is of Dexion angle, provided with a length of track and some stops to immobilise her in transit from the track to store and back. The trolley is described in Ch 17. Some splendid trolleys have been described in the model press from time to time. The modelmaker who intends to build up a locomotive stud, and take locomotives to club meets and similar events will do well to construct something similar to facilitate loading into the the car or van. One of the writer's acquaintances has a purpose-modified road trailer fitted with track on which two sizable locos can sit in transit, secured by bottle screws between strong points on the locomotives frames and the trailer body. Tool and coal storage is provided in the well of the trailer. The locomotives live on the trailer between meets and the trailer is ready for instant coupling to the family car, a good incentive to get out and about to meets and rallies.

As well as trolleys and trailers some ingenious hoists have been described in the model press, one hoist was designed to be coupled to the towing ball hitch on the back of a car for stability whilst lifting. The hoist used for handling Pixie, described later, is used to handle the locomotive in the workshop and at the garden track. It could be rendered more mobile by the insertion of splices in the leg frame to enable it to be transported by car. If this was done the original 'test load', two and a half bags of cement would be called into action once again to prove the mechanics. Hoisting a locomotive calls for a custom-built spreader bar to ensure that no damage is suffered in the course of a lift, and time spent getting the correct balance of the locomotive whilst suspended on such a spreader will ensure safety.

Pixie with some of the survey sketches

CHAPTER TWO

Establishing detail. Research. Manufacturers drawings. Commercially available designs. Value of the model press, exhibitions and club membership.

 

ESTABLISHING DETAIL

The amount of research required will depend upon whether the modeller chooses to produce an accurate scale model, or a near scale model. In the former case a massive amount of detail will be necessary, to the point of the sometimes derided ' rivet counting' exercise '. To embark on a scale model of a locomotive from 'scratch' is to commit oneself to many months and perhaps years of work. For the scale modeller every detail has significance, every modification to the original design has be faithfully reproduced and incorporated into the model. The problem here is that the components may prove to be too delicate to stand up to service on the track and there has to be a temptation towards some judicious beefing-up of parts. Fortunately if the choice is a narrow-gauge model on 5 inch gauge track the various components will work up to be quite substantial and durable in use.

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The near scale modeller whilst perhaps taking a more relaxed approach to detail has nevertheless to convey the atmosphere of prototype through the parts that he does include. He is fortunate in having the opportunity to make parts a little more solidly than they would be in true scale and thus a little less vulnerable to damage on the track. As we have said before modelling is a very personal process. Whatever the degree of scale accuracy is decided upon, careful research is required. The word

' Research ' sounds quite impressive. In fact it really describes a process that every enthusiast follows naturally in the course of enjoying his hobby, that of ferreting out detail on a topic which he finds interesting. The sources of information are many and varied, ranging from contact with individuals having personal knowledge of the topic, manufacturers, museum archives, libraries, railway sites, Model Engineering Societies and Preservation Societies. Once one's mind is set on a particular prototype there seems no end to the sources of information. The only problem is that in the back of one's mind there is always always the feeling that some source is being overlooked. The modeller may rest assured however, if there is some inaccuracy or anachronism, someone with expert knowledge will probably put him right at time of the models first public appearance!

MANUFACTURERS DRAWINGS AND PHOTOGRAPHS

We may be fortunate enough to have a sight of manufacturers drawings, if not directly, at second hand. Many of the books on narrow-gauge railways shew illustrations of these drawings which can be worked-up for use as detail in constructing a model. Photographs of locomotives in the outshopped state are an institution. No manufacturer ' worthy of his salt' would have outshopped a locomotive and sent it away to his customer without having it photographed in its pristine state. These photographs are worth their weight in gold to the enthusiastic model engineer who can enlarge detail and glean useful information for model making purposes. Failing works drawings or manufacturers photographs, the authors of many of the series of construction articles published in the model press base their work and the drawings accompanying the text on detail taken from manufacturers drawings.

Some books such as those on narrow-gauge lines noted in the bibliography include, as appendices, quite detailed drawings of the locomotives and stock of the lines they describe. When supplemented by detail derived from the photographic illustrations, these small scale drawings can provide sufficient detail for the model engineer wishing to produce a near scale model. Typical of these, and on the face of things an unlikely source book i s ' Narrow Gauge Railway Modelling ' by D A Boreham. Intended for workers in 7mm scale this book includes nicely produced general assembly drawings of such locomotives as Locomotives 1 & 2 of the Festiniog Railway and 'Mary' by W. G. Bagnall as worked by Cliffe Hill Granite Company. The book ' The Lynton and Barnstable Railway 1895-1935' by L.T. Catchpole includes works line drawings of the three Manning and Wardle locomotives and the Baldwin which reveal essential detail for the modelmaker.

Over the years some excellent, and generally quite accurate, outline drawings have been published in the model railway press devoted to 4mm and similar scale modelling. These drawings provide a basis for an excellent model when used in conjunction with standard details of parts gleaned from the pages of MODEL ENGINEERING and ENGINEERING IN MINIATURE and such standard works as LBSCs ' Shop Shed and Road ' and Martin Evans ' Manual of Model Steam Locomotive Construction '. Whilst in the main these books cater for the modeller working on standard gauge, mechanical principles do not vary from those of the narrower gauge. As discussed earlier much of narrow-gauge mechanical engineering is of a simpler design than that of the big stuff but there is no reason why, within the ' innards ' of a narrow gauge locomotive, one should not employ more advanced methods.

RESEARCH

A visit to the local library will reveal a wealth of publications touching upon the subject of narrow-gauge railway operations, locomotives and rolling stock. A brief perusal of the advertisements in the model press will serve to remind us of the considerable number of books available for purchase. A search of the stock on the bookstall at the next model railway exhibition will yield a surprising amount of information which is specific to narrow gauge. In the run-up to commencing a model, it is worthwhile copying or noting for reference material likely to be useful when the work begins. Often one encounters photographs showing useful detail in the most unlikely places. Newspapers, magazines, guide books and holiday advertisements have all yielded useful data in their time. The writer with his interest in sketching and drawing decided to measure from the prototype, meanwhile enjoying the visits to the line and contact with the volunteers working on the stock there. This may not be a feasible approach for many and other means of establishing detail become imperative. Brochures, postcards, and some posters for the Leighton Buzzard Narrow Gauge Railway provided photographs, which were of immense value in confirming detail achieved from survey. The modeller will do well to seek out similar details of his projected prototype.

Researching a model can be tremendous fun. Recent research took the writer to an industrial museum in the Midlands to meet a voluntary archivist. Working in the bowels of the museum this gentleman, a volunteer with years of experience within the engineering industry, specific to locomotive design and construction behind him, spends his time cataloguing works drawings saved from destruction at the time of the demise of an internationally known manufacturer. He has become known to many enthusiasts and is constantly called upon to supply information on requests from correspondents all over the the world. In fact, so busy are he and a colleague, that they cannot publicise their facilities in case excess demand should bring their activities to a halt! Perhaps in the course of research the reader will be fortunate enough to meet similar kind folk.

COMMERCIAL DESIGNS

During the past 20 years there have been many series of articles on the construction of narrow-gauge locomotives, notable are those on the construction of CONWAY, a freelance narrow-gauge 0-4-0 Saddle Tank locomotive for 3 1/2 inch gauge by Martin Evans, in MODEL ENGINEER of 1980. Other practical designs are the freelance model ' SWEET PEA ' mentioned earlier in this book and described in a series of articles in ENGINEERING IN MINIATURE. Whilst such designs are initially prepared for the benefit of the readers of the journal, commercial concerns soon set themselves up to provide the necessary materials and particularly castings for featured locomotives. In this way the modeller gains the advantage of an economic supply of raw materials and is, should he so wish, relieved of the work of producing his own patterns

The model engineer should not overlook designs for which part, or fully machined, sets of parts are available, particularly as these models have been built in large numbers and have proved themselves as runners on tracks throughout the world. Kits of ready machined parts such as those available from Messrs MAXITRACK have served to introduce many modellers to the delights of model engineering. Once having assembled a model from a set of parts, production and assembly of ones own parts seems just a small step to take.

THE MODEL PRESS, PUBLICATIONS, EXHIBITIONS AND CLUB MEMBERSHIP

As will be evidenced by the frequent references in this book, the writer is an avid reader of a number of model engineering publications. These range from MODEL ENGINEER and ENGINEERING IN MINIATURE to the excellent series of publications by such firms as ARGUS BOOKS and THE OAKWOOD PRESS. Magazines devoted to specialised topics such as small scale railway modelling have information to offer. It is well worth taking time to note articles which contain detail which can prove useful at some later date, a note of the magazine or source made in the diary or logbook can save hours of searching later.

Most of the existing narrow gauge railways have a bookshop at the main depot as do industrial museums up and down the country. Stocks within these shops often contain valuable information for the would-be modeller, most for example have some write-up of the history of the line and its equipment, or in the case of museums a description of a specific locomotive exhibit, containing valuable illustrations. Picture postcards and posters are another source of information and with care can be used to supplement surveys and drawings.

National and Local Exhibitions provide an opportunity for contact with trade suppliers, and other enthusiasts who can provide leads on sources of information. The models exhibited often reveal useful detail, and contact with the producer can assist in extending ones knowledge of methods and techniques. There is often a stand where known experts give demonstrations and provide advice on problems. Bookstalls at exhibitions can provide a useful source of information, on occasions it has been possible to pick up a years back numbers of journals for quite reasonable sums, reasonable when one considers the wealth of information contained therein.

Club membership has a great deal to offer, particularly where the newcomer to model engineering is concerned. There is never any shortage of know-how or advice. Frequently one or other of the members is specialist in or has specific knowledge of a particular railway, having perhaps worked on the line or more recently done voluntary work in preservation. Club membership may well present other advantages such as access to machines and services and sometimes discounted prices on materials from a local supplier. Local club programmes often include talks and demonstrations by visiting speakers, specialist in some branch of model making such as boilermaking, painting and so on, these events are particularly beneficial to the beginner.

CHAPTER THREE

Going it alone. Surveying a prototype. Equipment. A system of working. Ongoing visits. The database. Use of photographs and prints.

 

Pixie and Peter Pan at the Leighton Buzzard N. G. Railway

GOING IT ALONE

As we have seen there are many drawings available for narrow gauge locomotives, quite a number of kits of castings and indeed, even sets of parts for home assembly. It is however quite likely that the modeller has a particular prototype in mind, one that has fired his imagination, one that brings back fond memories from the past, or perhaps a locomotive to which access can be gained.

Where the prototype is one of the many that have passed on to the ' great engine shed in the sky' then some research will be required. Indeed, research of some order will be required whatever the reason behind the choice of a specific prototype. We are fortunate that the history of steam and steam railways in particular has been so thoroughly recorded by many devoted writers over the years, these constitute major works and will prompt further reading as a particular topic is followed up.

SURVEYING A PROTOTYPE

The cover of MODEL ENGINEER Vol 158 No 3795 Feb 1987 illustrates 'Rishra' and 'Challoner' of the Leighton Buzzard Narrow Gauge Railway. The remarks of the Editor of MODEL ENGINEER, Ted Jolliffe who took the photograph are apposite. He writes,' This shot was taken on one of the best days of last Summer at Pages Park Station, home of the Leighton Buzzard Narrow Gauge Railway. ' Rishra ' and ' Challoner ' pose together after double heading a Special Train, a charming sight and one which could well cause many modellers to dash to the railway armed with camera, ruler and sketch pad' ........ We know the feeling!

If one is fortunate enough to have access to the chosen prototype there are a number of things to consider in achieving sufficient detail for the construction of a convincing model. The locomotive may be sited on a preserved line, in a museum or may even be standing in derelict condition in a scrap yard. The important thing is to secure access. The first step will be an approach to the controller of a preserved line, the curator of a museum or the proprietor of a scrap yard. Permission to survey the prototype is generally given although there may be some stipulations regarding access times and so on. The thing uppermost in the minds of those in authority will be that of safety, both that of the visitor and those who work the line or run the museum. This is understandable in these days when responsibility and the rights of the individual are assuming such importance in life. It is essential that any visitor makes his presence known to those in charge in order that this safety can be preserved in the case of engine, stock or plant movements.

In the case of a locomotive preserved in a museum, one may be fortunate enough to find that drawings already exist, more than likely the curator or some enthusiast will have done some research already and will be prepared provide valuable information. In the case of a preserved locomotive it is likely that the line is in possession of at least some drawings from which copies or at least major dimensions may be taken.

In the case of PIXIE it was decided to make a complete survey, starting from scratch as described in this chapter. Where drawings or key dimensions are available, a lot of what is described can be omitted but in the interests of achieving a model of character it is advisable that, where possible, a visit or visits are made to the prototype for the purpose of achieving accuracy, and observing details that have either resulted from rebuilding or preservation work. Some detail changes are brought about simply by repair of wear and tear, or changes in the demands made upon the loco in service. For example, some small details such as the loops of tow that are used to lubricate the valve rods on PIXIE, the diesel couplers that were mounted for some years, the changes to the rear weather plate and the replacement of the riveted tank by one of welded construction with imitation rivets have been incorporated in the model to good advantage. We did not, however, incorporate the differences between wheels that have resulted from refurbishment over the years!

At an early stage it becomes necessary to decide on a ' base date' for the model. In the case of Pixie this was set as the date on which we first saw the locomotive. As well as the base date, the state in which the model is to be presented has to be determined. It takes a strong character to produce a model locomotive in pristine condition and then render it into a weathered condition! Mostly, we like to see our models in an outshopped state and not exhibiting the ravages of service. I decided to model Pixie as though she had just undergone a face-lift in the paint department but incorporating all the detail that I saw that magic day when I first saw her glide into Pages Park Station on the Leighton Buzzard Narrow Gauge Railway.

Having decided on the prototype it is time to start on the survey. I was fortunate to have the Leighton Buzzard Narrow Gauge Railway ' on the doorstep '. I had visited this line on a number of occasions and been struck by the friendly manner of all the volunteers who work the line. Not for nothing has the railway won its name as ' The friendly little line'. I gathered all the information I could from their publicity leaflets, and obtained some attractive posters, one of which showed my chosen prototype PIXIE the Kerr Stuart ' Wrenn ' Class saddle tank locomotive, built in 1922. The poster still adorns one wall in the workshop. This illustration and the memory of our first encounter acted as a spur to my efforts over the years.

At the Railway I soon established that the volunteers, among them the taxman, the accountant, the telecom engineer and a number of other interesting characters, were all pleased to help in any way they could. Access to the workshop was given by the Controller. Drivers, firemen and other functionaries took the greatest of pleasure in responding to my sometimes naive questions. I was able to time my visits to coincide with occasions when the locomotive was shedded for normal maintenance and repair, and one notable occasion when the boiler was to be subjected to inspection and test by the Insurance Inspector. Take time to develop a good relationship with the staff of your selected prototypes' line then you are sure to be accorded the same privileges.

Of course you may be fortunate enough to obtain copies of the works drawings from the manufacturer, or you may have gleaned sufficient information to build your model from your research. In the first case you will only have to scale down the detail, in the second you will need to prepare sufficient detail for construction planning and parts manufacture. In the case of Pixie sketches were produced from site measurements, not finished drawings but simple line drawings to be worked from at the various stages of construction. Examples of these sketches can be seen in the accompanying illustrations.

Plan the survey work. You can only make so many measurements in each session! Sometimes you will need a friend to hold the tape or direct the torch. You can't always bother the locals who are busy with their maintenance and restoration tasks. It is helpful to pre-prepare sketches from photographs so that you can enter the dimensions as you measure, failing this produce sketches on the spot. Bold outline sketches are best, it is difficult to sketch, measure and insert dimensions all at the same time. It is also difficult to convey to another person just what dimensions you are calling-off, so wherever possible enter the numbers yourself. On return to base, and as working sketches are prepared, make notes of any dimensions that are missing, these will be the first measurements to be taken on the next site visit. Do not be dismayed if on the first visit ( or two ) you miss some details, you will find with practice that you become more observant, and more inquisitive.

EQUIPMENT FOR THE SURVEY

Each individual will have differing ideas on the gear required for the preparation of measured details from a prototype. The equipment used by the author, whilst varying from visit to visit, included the following items;-

Clipboard, pencil (s) and paper, eraser, pencil sharpener or knife, measuring tape, steel rule, torch and a set square, ( on most occasions the edges of the clipboard sufficed)

Camera and flash equipment, preferably a single lens reflex model although todays compact cameras, with their built-in flash and zoom facilities provide excellent photographs. Dare we mention spare film!

Most of these items can be carried in a knapsack or some similar bag, nothing too special should be used as it is likely to accumulate its share of steam oil or grease! Mention of oil and grease brings to mind the need for a supply of ' Swarfega ' or some similar de-greasant, a bottle of water and an old towel. Not all loco sheds have supplies of such basic needs!

A SYSTEM OF WORKING

It is always advisable to phone the site prior to a visit, both to confirm that you may have access to the locomotive and to establish where it is to be found on the day, also what state it will be in. It is also useful to know how to dress for the visit, some days are 'clean' days and some decidedly dirty!

Now for taking the actual measurements. It is best to start by making simple sketches of the key items to be measured in the course of a visit, say a front beam, back plate or frame member. It makes good sense to keep groups of details on separate sheets, even at the risk of duplicating some detail. This will make reference to detail of particular parts of the locomotives easier in the workshop when a specific sheet of details can be isolated for reference. This also facilitates filing of the results of the survey, speeding the process of identifying dimensions.

Try to make each sketch to the same proportions as the member to be measured, later this will be facilitated by the use of photographs in producing sketches on which the dimensions can be set out. It is advisable to take running dimensions from a datum point thus avoiding inaccuracies due to the build up of small differences in measurement. In the absence of a helping hand, running dimensions can be taken single-handed by clamping one end of the tape to the feature forming the datum, and reading the tape at each point of interest ( remembering to pull the tape taut as each reading is taken, and ensuring that it is not snagged on some projection! ) Where taking details of groups of items such as bolts or rivets these should be sketched and measured, and the running dimension taken to a key point in the group. The individual rivet heads or bolts positions can then be related to this key point, and set out accordingly when interpreting the sketches back at base. At this stage with the tape in position, a photograph will reinforce the dimensions being noted. When the time comes to translate the detail the photo will serve as a reminder of odd little points which whilst clear on site fade in the mind between whiles. Things that are easily overlooked are material thicknesses, bolt, nut and washer sizes. Whilst measuring the plane surfaces it is also necessary to note such detail as plate thicknesses, pipe diameters, bolt and rivet head sizes and shapes. Where there are details such as cranked plates and coupling rods, dimensions of offsets have to be noted.. Sets in plate, or changes in plane, and similar detail which are critical to the overall appearance and ' atmosphere ' of the finished model should be noted and ' scrap ' sketches made for future reference. These scrap or local details are most useful in interpreting the overall picture presented by the dimensioned sketches. Brief notes help too, a note regarding colour, texture or material f some feature will save valuable time at a later date.

ONGOING VISITS

After the first visit it may be possible to mark up dimensions onto sketches taken from photographs or from slides, the former by tracing from a large print of a subject set upon a light box, alternatively on a sheet of glass or perspex placed over some suitable form of illumination such as a table lamp. Transparencies can be projected at a suitable size onto a piece of paper taped to the workshop wall and tracings made for use on the next visit to site. Judicious scaling of the projected picture will ensure that sufficient space is available for the insertion of dimensions at site.

At the commencement of a follow-up visit it is essential that outstanding queries are cleared up. This may necessitate further measurement or some discussion with a local, be he a curator, or a volunteer in the case of preserved locomotives. A point of caution here, enthusiasts can be very helpful but.....their memories are tinctured by their personal interests and any two taken together may come up with different opinions regarding when such and such a detail was modified or a particular feature added. In the course of conversations it is worth while listening for local ' intelligence ' such as a forthcoming ' shopping ' of the prototype or perhaps a boiler inspection. Visits timed to coincide with such events, with permission, will provide opportunities for examining the inner workings of the locomotive, the valve chests and boiler tube arrangements, blower ring and so on which would otherwise prove difficult when the loco is in service.

When working on the survey it is advisable to visualise how the model parts will be constructed, whether they will be machined from castings or fabricated. Whilst this does not affect the dimensions needed it does assist when the fabrication commences in the workshop.

THE 'DATABASE'

Information achieved at site will form the basis for some months and in some cases, some years of effort in the workshop so that on return to base it becomes necessary to store the details from survey in such a manner that they can be recovered at will. All rough sketches made at site should be retained, possibly in a box file. Photographs and file cards can be stored in boxes and slides filed in the containers in which they are returned from processing. It is advisable, in order to save time later, to segregate details under various headings such as ' Backhead', ' Smokebox' etc. Ideally, general assembly photographs will serve to tie the various items together and indicate the relationships of the individual subsections. During the course of constructing the model of PIXIE more than 180 photographs were taken in the form of transparencies and some 100 pages of notes and sketches were assembled. These are still retained today and act as a reminder when some adjustment or modification becomes necessary. Between visits and when not engaged in making parts in the workshop, some redrawing of details can assist in clarifying detail. It is advisable always to retain original sketches although they may have been superceded by a more recent, perhaps tidier sketch. There is often a need to return to the original to recap on some note or sketch made at the site. In this context it is advisable to make notes of details that present themselves during the survey, Where lock nuts are used, the position of a cotter pin and so on, later in the workshop one does not want to attempt feats of memory to establish what one saw months or years before.

PHOTOGRAPHIC RECORDS

Now we have digital photography and can wiew the images we take at whatever size is required on computer screen. Archiving is a simple matter and referencing simpler still. It still pays to take addition trouble to include tape and rules to enable sizes to be established back at base and special care over lighting to reveal the inner workings of the machanics of our subject.

Often there are posters and similar material which can yield useful information, as well as postcards perhaps, on sale at a kiosk illustrating our subject in earlier days.

The Internet provides a fund of images of virtually every locomotive that ever existed, simple to download and readily sizable on our computer, and again simple to archive.

It should al;ways be remembered that permission should be sought to photographon site. Safety arrangements have to be observed and also care should be taken regarding copyright of images from the web

 

CHAPTER FOUR

Workshop, tools and equipment. Practical aspects of heating, lighting and ventilation. Workshop practice for the model engineer. The logbook.

Old faithful of 30years...My Myford

WORKSHOP, TOOLS AND EQUIPMENT

This chapter ought really to be entitled ' Tools, equipment and workshop' because, whilst many books on the topic set out initially to describe in some detail the workshop facilities required, in practice the first requirement is some tools. The next requirement is some mechanical equipment and eventually a workshop, or rather a workplace! Of course it is ideal if one has a dedicated space in which to work, a place where everything can remain undisturbed between sessions, but it is a lucky man indeed who can start with such a space available. A great deal of work has been done in what were on the face of things, quite unlikely situations, in a first floor flat, in a roof space, onboard ship and countless other such awkward or uncomfortable places. At one time the writer made models on a fold-down bench sited, of all places, in the toilet ! Then followed a move to the loft via. the kitchen table and eventually, some years later it became possible to build an extension to the house and set up a formal workshop.

A great deal of useful work can be done simply by using hand tools, small parts being turned in an electric drill. Occasional access to a lathe and drill press, made possible perhaps by enrollment in an evening class or by ' chatting- up ' the maintenance engineer at one's place of work can bring the opportunity to progress further in the hobby. Several of the stationary engines which provided the basis of the author's model engineering experience were fabricated piece-part fashion using such facilities..... ........Maintenance engineers often turn out to be steam enthusiasts at heart!

The pleasure to be obtained from our hobby can be realised in a number of ways. One of these revolves around pride in possessing the necessary tools for the job, sometimes obtained as a result of some sacrifice such as giving up smoking, or forgoing some other pleasure. There is also the satisfaction to be taken from achieving something which would normally be considered beyond the scope of the simple equipment which we may have acquired. Whilst other delights of model engineering have been touched upon earlier in the book, the challenge of achieving, what once may have seemed to be if not impossible, extremely difficult, using available equipment and facilities still features heavily in the enjoyment stakes!

TOOLS

Tools are a joy, however acquired either purchased in pristine condition from a first class tool shop or from other sources such as garage or car-boot sales, possibly in need of renovation. The tools that give the greatest pleasure are often those passed on to us from relatives or friends. Tools may have been handed down from departed relatives and considerable pleasure can be obtained as using them prompts remembrance.. Use on the current project prompts thoughts of the original owner, such as the old tool maker who on his retirement made us a present of his micrometer and other measuring tackle. As experience grows the modeller will probably design and make some special tools, these are particularly precious in meeting an identified need and are special to the maker.

It is important to buy the best tools that can be afforded, they will if properly maintained probably outlive us and be passed on to sons (and daughters). Where possible, a workshop set of tools should be maintained as distinct from the general kit used in the garage and on DIY work about the house and garden. When a loan is requested, lend from the general kit! Mainly tools are acquired as the need arises although most of us will have to admit to making purchases on an impulse, particularly at the magical MODEL ENGINEER EXHIBITION where there is the opportunity of making some fantastic purchases. It makes sense to go to the exhibition with a shopping list of items necessary to bring tool stocks up to standard, it offers a grand opportunity for replacing broken small items such as taps and drills. It is very difficult to withstand the urge to snap up bargains and indeed often return with such ' bargains ', perhaps wondering what prompted the purchase yet secure in the knowledge that they will come in useful one day

!MEASURING TACKLE AND INSTRUMENTS

Apart from the aforementioned micrometer the following equipment, listed in order of aquisition, meets all the requirements of model making on models up to 5" gauge:-

Good quality steel rules in 300 and 150 mm lengths, squares of various sizes, inside and outside calipers, oddleg caliper, 0-150mm vernier caliper gauge, height gauge, mm dial gauge, surface plate ( mine is 250 x 200mm obtained second hand ), magnetic stand for dial gauge also various scribers. Although the sizes are quoted in millimetres the workshop still boasts a set of Imperial equipment and much of the work is carried out in ' dear old ' feet and inches.

Later additions to the outfit include some inside micrometers, obtained secondhand, a centre finder, a wiggler set for edge and centre-finding, pair of vee blocks and a huge, ex-WD, caliper, purchased for a song in an open market. A dial caliper gauge ( the pride of my life, bought as a bargain at the MODEL ENGINEER EXHIBITION ) is in constant use. As model engineers rather than engineers, much of our work involves working to fits rather than critical dimensions. The dial caliper provides a speedy yet sufficiently accurate means of comparing sizes whether internal, external or depth. The current generation of digital gauges are of course even more dynamic to use and will prove to be worth the ' arm and a leg ' they may cost. The great advantage is that these instruments can be zeroed at any dimension and thus directly indicate differences between measurements.

A recent aquisition, a magnetic-based holder for a dial gauge, has proved extremely useful. It is used the course of turning, milling and drilling to measure tool feeds. With the base set onto the machine bed and the magnet actuated, a dial gauge can be set to bear against a table or slide such that the travel or depth of feed can be directly read from the gauge as work proceeds. It is far easier in some cases to read the gauge thus set-up, than it is to read the micrometer dial on the machine.

HAND TOOLS

The number and type of tools that one uses is a very personal thing, excellent models are built by some modellers equipped with what could be regarded as the absolute minimum of tools.
It is preferable as far as possible to have the correct tool for the job, sometimes to the extent of 'overkill'!

Again in the order of aquisition the following tools have permitted the production of a series of models up to 5" gauge:-

An assortment of saws including 'senior' and 'junior' hacksaws and a coping saw. Hammers, ball pein, claw and pin, also a builders lump hammer for persuasion of heavy sections! An assortment of files and some rasps. A short set of ( expensive ) jewelers files have proved invaluable Pliers of assorted shape also a pair of steelfixers ' nips ' and two sizes of tin snips, one having curved blades. Chisels, punches of various sizes and an ' automatic ' centre punch. A wheel brace and an electric drill, later supplemented by the aquisition of a high speed mini-drill and variable speed control. A variety of clamps include ' Mole ' overlever clamps, 'G' clamps and a range of tool makers clamps. A hot-glue gun has proved useful, particularly for locating small or thin parts during machining operations! Screwdrivers include the good old ' engineers pattern driver, electrical and watchmakers screwdrivers. Several adjustable spanners are used,for rough work but for actual work on models only good quality open ended, or socket spanners are used. Messrs Proop's ' Doofers ' come in useful at many stages.

Drill bitts have been purchased over the years to the stage where number sizes are supported as are Imperial and letter sizes to about 1 / 2" diameter maximum. Taps and dies have been purchased as the need has arisen and most sizes from 9 BA to 1 / 2" are held, together with the necessary stocks and tapholders.

TOOL STORAGE

Tools are stored on boards, either wall mounted or, in the case of small tools, fixed as riser boards on the back edge of the benches. The location of tools on these boards is determined by the place in which they are most often used, chuck keys adjacent to the drills, tommy bars adjacent to the mill, small tools adjacent to the clean bench and so on. Tools which see only occasional use are stored in file trays picked up cheaply in a car boot sale. Portable power tools and lathe accessories are sited in cabinets, again wall-mounted, with glass doors to ward off the ever present workshop dust.

BENCHES

Bench height is a very personal thing, the vices must be at the right height for filing and sawing operations, in the writers case 32 inches from floor level, yet for very fine work it is often necessary to have them higher as does a watchmaker. This is achieved by having a supplementary worktop which rest on the standard bench and can be secured when necessary by clamps, or mounted in the vices.

Within the workshop it seems that one can never have enough benches or worktops. Just as it is sometimes said that ' work expands to fill time ', so things multiply to fill workspace ! Nearly 2 / 3 rds of the perimeter of the workshop is allocated to worktops or benches. Some discipline has to be maintained here, one bench is the ' dirty bench ', one the ' clean bench ' and the other the light, mobile bench. The first two speak for themselves, although there is a need for strong discipline to keep the clean bench, used for electronics and fine work, really clean ! The dirty bench is for the heavy work of preparing metal for machining.

The mobile bench is a recent production, made from DEXION angle, it is set to match the height of the fixed benchwork and can be used in its own right for light fabrication work, or appended to the fixed benches to accomodate overlong pieces of work. The castors are of the heavy industrial type and are set so that the uprights of the assembly just clear the floor. When any particularly heavy task is to be undertaken it is a matter only of a few seconds work to insert thin wedges to take the strain off the castors. The bench is used for final assembly of clean items and can be sited according to the work in hand, against the lathe as a repository for tools between uses or adjacent to the benches as required. It is useful to have space to 'park' small tools in the course of work, to hand yet not cluttering the available worktop. A particular advantage to be gained from a mobile bench is that, sited in the right place in the workshop, it provides a base on which a length of portable track can be mounted for service work, adjustments to the loco and so on. A short length of 3/4 inch plywood is used to bridge between the fixed and mobile benches and access is available all round the 'island' so formed.

VICES

Vices are mounted on secondary pieces of benchtop which allow their location to be changed to suit the work in hand. The heavy ply bases for the vices were drilled to template, as were the benchtops and it is a matter of a few minutes work to change things around as required whether for heavy or light work, working in wood, metal or plastics. As well as the normal duties of holding metal for sawing, filing etc. the two metalworking vices mounted in tandem are used for folding and bending plate materials. There is a woodworking vice, this swivels and has the useful facility of reversible jaws which permit gripping material up to 7 inches wide. Cramps include toolmakers, mole, screwclamps as used in woodworking and some excellent clamps which whilst intended to be used as screw clamps can if supplemented by a 3/4" stock bar be used in clamping lengths limited only by the available bar. 'Grippery' is competed by a small parts, universal vice built to a design published in MODEL ENGINEER, this is invaluable for small part assembly and the investment of the 2 or 3 hours expended in its construction has been repaid many times over.

MACHINE TOOLS

The King of the workshop in these scales is without doubt the Myford 7 series lathe. We graduated to this from a Unimat via a very ancient but extremely trusty Zyto lathe, purchased second-hand which was used in building a series of Stuart Turner stationary engines. The Myford is equipped with 3 and 4 jaw chucks, faceplate, and a swiveling vertical table. Drill chucks to 1 / 2" and a home- built die holder for the tailstock complete the lathe equipment proper although a number of accessories have been built including boring and knurling tools, wobblers, height gauges and so on from descriptions in MODEL ENGINEER over the years.

The first exercise with the Myford was the construction of a sensitive drill to a design from Messrs Reeves catalogue. The necessary castings and raw metal were purchased from Reeves and provided excellent practice in turning, boring and so on. The parts worked-up into an extremely accurate piece of workshop equipment which allows the use of the smallest number drills without breakages. With small number drills it is important that one gets the 'feel' of the drill as it cuts metal, particularly at the critical time just before and at break through, the Reeves drill provides just that feel. One addition ,in the interests of safety was the inclusion of a perspex, ' wrap-around ' guard for the belt drive which otherwise is running just inches from the users face in course of work. This machine has been replaced in recent years by a 'cheap and cheerful' drill press of doubtful ancestry, and recently a small universal milling machine was purchased to suplement the armoury.

A throwback from the days of wooden models is a a small bandsaw. this is invaluable for producing templates and for cutting the odd bit of packing timber. It can be used for light metal cutting which is of course also carried out using a hacksaw and brute force. A 'nibbler' has proved useful in cutting thin sheet for cleading and similar purposes.

THE WORKSHOP BUILDING

Given the opportunity to have a dedicated building for the workshop there are so many possibilities that a description would fill another volume. We have been fortunate enough to be able to build an extension to the house, brick built, properly heated, insulated and lighted, with power and water available.

The workshop which was described in MODEL ENGINEER Vol 163 No.3853 really is a ' quart in a pint pot as the Editor described it at that time '. The best advice stemming from experience must be that one should think of a size, and double it! As with all building work, the finished result always seems smaller than the drawings indicated, and anyway extra space can always be put to good use until filled with that new machine or additional storage shelves.

A well insulated timber building can be used as a workshop, as can the space at the back of the garage, and most of us know model engineers who produce excellent work in such places. A covered access from the house is desirable as in the depths of winter it takes some strength of character to leave the warmth of the house and brave the elements to get to the workshop! In the case of the timber building it is essential to insulate the walls AND THE ROOF. The latter often being overlooked can be responsible for massive heat loss and consequent condensation. The walls should be lined with something smooth to permit ease of cleansing and ideally the floor should have heavy lino or tiles to permit sweeping, thus simplifying the location of those small parts which insist on gravitating to the floor, ( and under the nearest machine or bench ! ) Double glazing, or at the least, secondary glazing of any structure is a further weapon in the fight against condensation as well as retaining such heat as can be introduced by some ' dry ' form of heating. A centrally heated workplace is of course a luxury. Low wattage tubular heaters have a lot to offer in the smaller or the isolated workshop. A time switch can be a benefit as the heating cycle can then be optimised to suit workshop ' hours ' whilst maintaining the gentle heat required to preserve tools and equipment.

SERVICES

Plenty of power points at bench height are a must. Provided that substantial cable is used these can be supplemented by extension leads with multiple outlets ( switched and fused ). We have a preference for general fluorescent lighting, local intensity of light being provided by anglepoise or similar fittings. Whilst low voltage lighting is ideal, normal mains voltage equipment has been used for many years without problem or accident, of course these lamps whether free standing, wall mounted or mobile are properly earthed and never mounted on the machines. The use of a circuit breaker is essential where portable power tools are used. On the topic of electricity, one of the most useful pieces of equipment that I possess is a rather ancient meter, this measures current, resistance and other detail to complicated for my ' ken ' but proves invaluable in checking lamps, earthing of equipment and the like

Access to a sink, adjacent to the workshop yet not in it, is a great asset, providing for the cooling of metal, scrubbing down prior to soldering and so on. A sink which has become too disreputable for normal domestic use is ideal, and an old sink is usually accompanied by some old taps, so that the installation can be carried out by the model engineer with access to appropriate pipes economically and in no time at all !

VENTILATION

Many hours are spent in the workshop environment and thought must be given to good ventilation. As some of the operations, such as those of machining cast iron and gunmetal generate a very fine dust we must look after our lungs. A good quality mask will do much to save the respiratory system from attack but the quality of the mask and the suitability of the cartridge to the work in hand is all-important.

The writers workshop is ventilated using a very large, Vent-axia fan bought in a car-boot sale, this is mounted in a box INSIDE one of the the fanlights in such a way that the fanlight can be opened and closed in the normal fashion for general ventilation purposes. When a forced draught is required the fanlight is set wide, the fan switched on, and a hinged perspex inner pane is buttoned down to blank-off the fanlight opening beside the fan housing. The fan now produces anything between a mild breeze and a howling gale. Air circulation is also assisted by two smaller fans, as used in cooling computers, set over the lathe and the milling machine. These fans which are attached by clamps can be moved easily, and as they are brushless can also be used to flush away the fumes from any small painting operations carried out in the shop.

THE LOGBOOK

As a keen diarist some entry is made in the diary each day. At the same time the hours spent in the workshop are noted, also the activities. This odd quarter-hour or so, each evening is spent noting down details of the way in which things have been assembled, screw and fixing sizes and other details that will prove useful, both when the time comes to take the model down and re-assemble it, and when remaking parts. The information should also prove useful to anyone who may own the models in the future. As well as details of finished work, part of the entries will be sketches of the next component to be fabricated together with a planned sequence of machining operations ( Often in the ' heat of the moment t' in the workshop the sequence may be changed but brief notes ensure an awareness of critical dimensions and intended secondary set-ups ) It is also helpful to note down any items which need to be checked when next visiting the prototype.

It is said that sketch is worth a thousand words, many times now notes have disclosed a detail that had slipped the memory......... after all some models take many years to build and a lot of detail becomes buried as work proceeds. As an example, recently, due to some corrosion around the regulator gland it was decided that the mild steel studs and nuts be replaced by new ones from stainless steel. A few moments spent with the logbook confirmed that 5BA studs and nuts had been used, and not 1 / 8 inch M.E. as they appeared on first inspection. So, as the result of a few jottings some years ago, as well as valuable time being saved the likelihood of a damaged regulator body was avoided. Other notes made include references to articles in MODEL ENGINEER and ENGINEERING IN MINIATURE for future use when a particular operation is to be tackled. Some notes are reminders, which form a shopping list and ensure that a component cant be produced for lack of the raw material or a particular tool, say a drill, tap or other such item easily forgotten when at the shop.

On completion of a model, with reference to the logbook, it is worthwhile to prepare a set of cards, 150 x 100 index cards are ideal for the purpose. These shew the sequence of erection, fixing and fastening sizes and other detail that a future owner may find useful in running and maintaining the model. These form something like a simplified workshop manual such as one may have for a motorcar. A computer
' buff ' could set up a useful database in which to record a number of the details mentioned, although this may not prove so accessible to others at a later date.

Indexing 4 tool toolpost mainly from scrap

CHAPTER FIVE

Materials. Sources of supply. Organised storage and the scrap box. Modifying available materials. An introduction to simple pattern making.

SOURCES OF SUPPLY

Sourcing of material is an important aspect of model making. The writer makes no secret of the fact that a large part of the materials used in modelmaking is scavenged from scrap bins and 'Biffa' skips (with permission from the owner of course). We have also benefitted from the miscellaneous selections of ironmongery to be found at road junctions and similar spots where vehicles, waiting for traffic lights to change, shake themselves to pieces. Judging from the range of screws, bolts and miscellaneous metal sections one finds, much of our countries' transport fleet must be in imminent danger of collapse!

Much of the benchwork and shelving in the workshop, as well as the lighting fixtures and associated wiring have come from skips. Proprietors of the local engineering works are very helpful in this respect, to the extent that, knowing our interests they set aside any particularly useful items of scrap! Once they become aware of ones interest, friends often turn up with interesting bits of metal which can yield useful raw materials. There will be however a number of materials which have to be purchased and much of these will come from the suppliers who advertise in the model press. A good source of materials is the advertiser who puts up packs of useful sizes of bar and rod. A selection of these bundles forms a good basis for a modelmakers stock. Of course not all the materials will have an immediate application in the sizes purchased but a hacksaw and some elbow grease work wonders!

ORGANISED STORAGE

It is important to be able to access ones stock quickly and simply. Care in segregating materials and storing them in such a fashion that they are not damaged in store is just one further facet of the model engineering hobby. It makes sense to run ones stock in much the way it would be organised in a commercial workshop, noting when stocks are getting low and thus not finding oneself in a situation where materials have to be used wastefully to obtain the particular section required.

Containers suitable for storing small parts and materials are available in a variety of materials, largely steel and plastic. Often job-lots of containers can be purchased at auction. File trays are excellent for the storage of short ends of bar, oddments that prove so useful, provided one can lay hands on the when the need arises. Different materials can be segregated in such trays, mild steel in one, nonferrous in another and so on. A simple wooden or welded steel frame allows such a number of trays to be stacked and reduce the uptake of space. For smaller items plastic icecream containers are useful, honey jars are excellent for small bolts, screws etc. rotate the jar and give it a shake and the bolt screw that you seek will pop into view!

Some simple methods for storing material:-

Medium length pieces of bar, rod and tube can be stored vertically in racks comprising two grillages of steel bar fixed to a wall of the workshop, one to locate the bottom of the stock and the other to support the material 3 foot or so above floor level.

Short pieces of these materials can be stored in lengths of plastic drainpipe. The pipes can be cemented together and banks of such pipes allow both easy access and a quick check on stockholdings. Similar banks constructed from wastepipe and conduit will control stocks of small diameter tubing.

Multiple-draw storage units are available from DIY stores or can easily be manufactured in the workshop. Being wall-mounted they save space. Drawers marked with their contents will save hours of searching.

Drills are best stored in racks, simply made from wood blocks, it will save time too if tapping and clearance sized drills are stored together with the screwing tackle. Draws marked 'Small number drills', 'Small cutting tools', 'Centre bitts', 'Unions', 'springs', 'Washers' and so on, used methodically also save time and avoid frayed tempers.

Jars and ice cream containers are useful for storing small offcuts, nuts bolts and similar items, labeling saves precious minutes of time which will otherwise be expended in searching for an elusive piece!

When seeking space in which to store tools and materials remember to consider the space over, as well as, under that crowded benchwork. With a brick-built workshop and in some cases in timber framed buildings quite substantial loads can be supported in custom-built shelf frames, suspended from the roof members or fixed back to the walls. The shelf frames should be supported in such a way that the majority of the loading is applied to the wall fixings in shear, vertically downwards at the face of the wall. Shelf units placed strategically above the benchwork, leaving adequate working space also permit the installation of lighting units below the shelving providing a good working environment below.

Some of the materials used in the model engineering hobby are quite aggressive, some such as acids and certain paints require special storage. These are best kept in a metal cabinet, locked if there are 'little people' about the house. This is another instance where the same care should be taken over storage as is taken in industry.

THE SCRAP BOX

The first port of call when seeking materials for a part of the locomotive will be the scrap box, or that odd corner of the garage or shed where those bits of metal ' that may come in useful one day ' are stored. That day is bound to come, and provided we weren't too ruthless the last time we sorted through in the pursuit of space, we will find at least a few pieces that can be pressed into service in our project. The materials may not be exactly what we need and it needs imagination to see how we can use some of the stuff. It may be that, rather than providing material for the locomotive proper, some pieces will provide the basis for jigs or templates to assist in the construction or erection work. Scrap angle steel such as that from an old bedstead whilst being virtually ' Monkey metal ' could prove to be useful in the manufacture of an erection frame. Dexion angle can be used in mocking-up a driving trolley, scraps of plate may be used as the backplate for the jig on which the horn casting will be machined and so on.

A well-organised scrap box is an important asset. Some time spent in dismantling a defunct television set, a radio, damaged video tape case or virtually any piece of domestic equipment can yield supplies of a range of materials from self-tapping screws to sheet metal bracketry. Admittedly the current trend in commercial manufacture towards ' throw away ' engineering practice leaves less of a recoverable nature, but there is always some small thing worth keeping.

MODIFYING AVAILABLE MATERIALS

Often material of the section or length required for the current component may not be available. With some adjustment either by way of a change of material or method something from stock may be brought into service. Re-cycling, sawing down angle, splitting tube, using chucking pieces saved from castings as bushes and similar dodges can save money and time. Even pieces that were spoiled in some previous operation, and probably thrown into the scrap box in disgust can prove useful when cleaned-up, cut-up and re-machined. Whilst apparently a wasteful process, producing studs by cutting the threaded portion from a bolt can be productive in that one finishes up with a stud, and an embryo bolt albeit one of much reduced length! Conversely, the small threaded offcut that is saved after a bolt has been reduced in length may well be pressed into service as a grub-screw in another application. Keep a few containers marked ' Small brass ', ' Small steel ' and so on, and you may be surprised how often you find just the piece of material that suits the current requirement.

It is occasionally possible to find alternative uses for items which would otherwise be considered as domestic or garden hardware. instances of this are small sized hinges which can be reduced for use in a model, studding sold at the ironmongers, again for domestic use which can be brought into service as tie bolts for securing material for machining in the lathe or milling machine. Stores retailing automotive parts sell metal and rubber tube in various sizes and gauges also shim brass and steel and a number of fixings which can be put to use in models. DIY stores stock a number of standard sections of brass, aluminium and plastic which may meet a modelling need at some time. Even the local supermarket will stock polishes, scourers and abrasive materials which can be used in metal finishing. A number of the shops market spun or pressed metal products such as trays, bowl and eggcups, some in stainless steel others in brass. The materials and sometimes the geometric shape of these present possibilities to the model engineer, an example that springs to mind is that of the steam dome cover cut from the bottom of a spun brass vase!. The search for alternative and economic sources of material can be quite fun and may, to some extent, relieve the boredom of a domestic shopping outing.

SIMPLE PATTERN MAKING

There have been many excellent articles, indeed a number of series of articles in the model press on the topic of pattern making. The topic is interesting and one which, given time, could become all-engrossing. Ones time available for model engineering activities is often limited. With such limits there might be some reluctance to spend the time and energy required for the manufacture of the more intricate pattern work required by a project. In this case two courses present themselves. The necessary casting may be obtained, as in the case of the horns for Pixie, by modifying some nearly similar, available casting. Alternatively one may turn-to and make simple patterns which, whilst probably beneath the contempt of the dedicated pattern making modeller, yield castings which can, by careful machining, permit the production of the required part.

Simple patterns may be carved from wood or, in the case of circular work, ' horsed ' from plaster. Simple wooden patterns need no further description, as long as the resulting castings include the principal detail and enclose the outline of the required part, once the casting has been produced only straight forward machining operations will be required to produce the required component. Of course the amount of machining has to be limited to work that can be carried out with the equipment available in the workshop. Firms producing castings have readily accepted and cast from my simple patterns.

Plaster patterns can be simply produced for the most complicated parts and will provide the one or two uses required for most model casting needs. Regarding the ' horsing ' of plaster to p[roduce circular work such as wheels, this is an age-old skill yet one which has often been overlooked. The technique which was used for the smokebox rings for Pixie involves the preparation of a sheet metal template of the required section ( plasterers use galvanised material, but for our short-lived requirements any sheet will do ) The template is furnished with a pin which can be inserted into a piece of plate, large enough to accommodate the required pattern. the plate is very lightly oiled and the oil wiped away to leave just a suspicion of greasiness and the plaster laid approximately to the required shape. Judicious ' horsing '( scraping ) with the template around the pin generates a plaster master which when hard and coated with two or three coats of shellac or paint can be used to produce several castings. In each case the necessary allowances must be made for shrinkage, and it has to be remembered the finished casting will reflect faithfully the standard of finish imparted to the pattern.

 

CHAPTER SIX

 

Sketches to indicate approach to making axleboxes, hornblocks and dieblock guides for the model of Pixie

Planning. Model engineering with pencil and paper. Machining sequence. Fabrication vs. the use of castings. Use of models, mock-ups, jigs and templates.

GETTING STARTED

With a portfolio of dimensioned sketches and a considerable number of photographs under the belt it is time to make a start on planning the model. This is the time to do some taking-off of materials, not only establishing immediate needs but listing and probably budgeting for, the future. Ours is fortunately a long term hobby, and there are many facets to each project. Once the main equipment has been bought or made or at least a way of accessing equipment has been established, perhaps via a local evening class or community centre, the materials for a model can be bought in step with progress in making the model. This is a major economic ' plus ', bearing in mind the cost of materials, particularly the more exotic ones, such as stainless steel and phosphor bronze for which there are few serviceable replacements.

It is decision time once again! Looking through our sketches and visualising the model it becomes necessary to determine whether standard castings that approximate to those required for the model are to be used or modified, or whether parts will be fabricated from raw materials. The alternative, and this may be time consuming, is to have castings made from patterns which will be time consuming to produce. Fortunately much of this deliberation can be carried out away from the workshop, in the lounge whilst others watch the television, or during boring business meetings, there is no end to the scope! In practice, a lot of thinking can be done in the workshop or garage where the materials can be handled and their possibilities pondered. Pixie's chimney was turned from reinforcing steel from a building site, the platework once comprised the instrument panel on a piece of control equipment, the chassis for the driving trolley was in a previous existence part of a steel door, and so on. In many instances a considerable amount of work was required to rework the material and prepare it for the operations that would transform it into a part of the model. Often a whole evening's modelling time was spent in sawing or shaping ' rough stuff ' to a stage where marking out and the work of machining proper could be commenced. It adds to the pleasure obtained from the hobby to be economic with materials and be prepared to do some re-cycling!

PENCIL AND PAPER

The scrap pad or the notebook is a vital tool in model engineering. Time spent, pencil in hand will yield immense savings in the time required to produce parts for a model. No matter what our artistic abilities, as long as WE can understand our notes and sketches that is all that really matters! Sketches of the parts required for the model, ideally full size, worked-up from our details and dimensions, will give us a feeling for their eventual shape, size and ' heft '. With a sensible sketch in hand a start can be made on figuring out the material requirements, and visualising key operations in producing the part. Some of the operations will be those standard operations described so often, and so capably, by the expert writers in the model journals. These replicate to a large degree the actual methods used in the construction of the prototype. In many instances however because of the implications of available equipment or available material we have to be our own method engineer and consultant combined, and devise original techniques. The methods so arrived at may not of course be completely original, modellers have a saying that there is a precedent for everything. Whatever we re-invent however will give us immense satisfaction when successfully put into practice.

WORKING DETAILS

Whether, or not, to produce scale drawings will depend upon individual preference, The writer works from sketches prepared from the site sketches, often after making several different sketch views of the item as described elsewhere. For detail which is critical mechanically, such as valve gear and motion work, measured drawings are made at the drawing board ( Well actually the pastry board! ), often twice full size. These can be used in conjunction with cut-card components to establish valve events, critical clearances etc.

The amount of drawings prepared will depend upon one's skill with pencil and paper, and indeed on one's particular interests. We all tackle jobs differently. In the case of ' Pixie ' many sketches were made, from all viewpoints. After some time spent in this way the part can probably be drawn from memory . This is very helpful when it comes to the time to decide upon the materials and methods to be employed, also in the course of work in the workshop. Some modellers are happier cutting metal but even they will have to sort out the overall sizes and details to enable the selection of an appropriate piece of stock. Working from the dimensions obtained during the survey each part may be sketched, as near to model size as possible. Some modellers may prefer to use one of the lap-top drawing boards complete with miniature drafting machine, others may even use a computer with a CAD programme. The writer prefers to work in sketch form on a pad of A4 paper, this can be done virtually anywhere, even in the bath!

It is worthwhile making a series of sketches of the part in the various stages of production. In this way the sequence of operations in producing the part can be visualised and suitable chucking or fixing points provided. Choice of a poor sequence of operations can make completion of machining difficult or even result in the production of a substandard finish. Ideally, once a part is set into a chuck or mounted in a fixture it should only be removed once operations critical to concentricity or line are completed. Re-chucking a part causes problems, especially for newcomers in their early days in the hobby. Turned mandrels are often the solution to the problem and the need for these, and suitable jigs to hold small parts for finishing operations, will become apparent on paper as each stage of production is examined in detail.

As an aside, a fixture which the model engineer may like to use as a design exercise is a means of supporting 3 jaw or 4 jaw chucks, and faceplates OFF the lathe. As well as allowing set-ups to be established in comfort on the workbench, such a fitting is useful in holding material whilst setting out and during milling operations. The lathe manufacturer generally offers as an accessory a threaded mandrel replicating the headstock thread and it is a simple matter to attach this to a backplate drilled to match the slots on the top table of the lathe, the milling machine, drilling machine etc. Make a few sketches, dig out the necessary plate from the scrap box, buy, or better still, fabricate a replica of the spindle nose. A suitably threaded nosepiece can cut from a spare intended for use in the tailstock, leaving a useful No 2 Morse taper mandrel which can subsequently be drilled and tapped for use as a backstop when machining thin discs in the 3 or 4 jaw chuck. The result, provided care is taken to ensure accuracy of the fixture, as well as providing an exercise in sketching, simple method engineering and some turning and fabrication work, is a most useful piece of workshop equipment.

SCALING DIMENSIONS - ' SCALEDNESS

There will be occasions where small adjustments or a compromise has to be made between dimensions established from survey and those to which the model parts are eventually prepared. These adjustments may be required to simplify something which otherwise would be over complicated to manufacture with the means at one's disposal, to overcome erection difficulties or to ensure that model parts are sufficiently robust to be durable in service. Where a scale 4" axle may be required the writer has no qualms about using the nearest available stock size, in this case, to 2 1/2 inch to the foot scale, 0.875 diameter. This is not laziness, or a reluctance to spend time on a machining operation, rather it constitutes the approach taken in value engineering. Time saved by eliminating the machining operation may well be put to better advantage preparing some other more critical part. Whilst this approach may not suit the purist, it is one that most people will find they can live with !

Instances of compromise made in the course of constructing the model of PIXIE were increased thickness of the plates used for frames and some thinning of parts of the motion. There were one or two other situations such as the axles where, as noted above, stock bar was used rather than material turned to scale diameter. The amount of adjustments made by the individual will be determined by personal preference and standards. At one stage consideration was given to the unprototypical move of splitting the smokebox horizontally, making the top half removable in order to facilitate access for installing the blast pipe, wet header and so on. Even in 2 1/2 " to the foot scale it is difficult to get fingers and especially spanners to the fittings for the blower and such items within the smokebox. Some thought was given to Martin Evans comments in ' Manual of Model Steam Locomotive Construction ' where he recommends split smokeboxes, in that instance for 1" scale locomotives. Eventually the decision was taken to use a piece of large diameter steel steam pipe, turned to size, and in the event after much fiddling and bruised knuckles the exhaust pipes were ' persuaded ' into place. The decision has been regretted since however, as the substantial exhaust pipes and blower ring make it difficult to sweep the boiler tubes. A rebuild would include a split smokebox !

FABRICATION Vs. CASTINGS

As our working sketches develop we will be better placed to visualise the finished part in model form. as our prototype is a narrow gauge locomotive if we are working in 2 1/2" to the foot scale we are drawing components which are, linearly speaking, approximately 1 / 6th full size. The finished model parts will be quite substantial and correspondingly weighty. It may well be that if we are constructing a model of an unusual prototype, and one for which there are few commercially available part, we may choose to fabricate components rather than make patterns for our local foundry. The coupling blocks and weighshaft brackets for Pixie were unusual to a degree and it being unlikely that more than two uses would be obtained from patterns, these items were fabricated. Such castings as were bought-in were cast from simplified patterns or, in the case of the horns, were modifications of castings produced commercially for other prototypes. Fabrication allows for economic use of material and in some instances economical use of available time. Pattern making is a time consuming, although enjoyable pastime, offering as it does a change from metal working practice and it does provide another most interesting avenue or aspect of manufacturing technology to be explored. Where club membership provides contact with other enthusiasts it may well prove worthwhile spending time making conventional patterns when the use can be shared with fellow members. Equally if a batch of locomotives were in course of construction then patterns providing multiple casts would be favourite.

MODELS, MOCK-UPS ( and test pieces )

The mock-up is an essential stage in automotive, aircraft and many types of full size engineering.Due to small discrepancies in scaling of parts, or the accuracy of our production, it becomes increasingly essential in our model making, . As production of our model parts proceeds models ' mock-ups ' help us to ensure proper fits in the final erection stage. For ' Pixie ' a card model was made and superimposed on the general assembly sketch of the frames and cylinder casting to determine acceptable events in the valve settings. A model of the boiler fabricated from stout card was used to ensure that the boiler, as detailed, could be fitted between the frames. A further model of the saddle tank proved the position of the mounting brackets on the boiler, and so on.

On a larger scale, a dexion angle mock-up was made of the driving trolley to ensure a comfortable seating position with access to the controls, this was subsequently translated into the trolley described in Ch xx and has proved to be safe, stable and comfortable in service.

Model assemblies are especially important if, as in the case of the model of PIXIE, parts are being made from a series of sketches rather than a full set of finished drawings. There are however a number of instances such as those quoted where details can be proved ' in the round ' in mock up form, a task which would account for no little amount of head scratching in the two dimensions of a drawing. Apart from the technical reasons calling for the use of mock-ups there is a great deal of satisfaction to be obtained from the preview of the finished article presented by even the simplest model!

Where some new material or technique is to be employed, time spent on a test piece or pieces is time well spent. instances where tests were performed in the production of Pixie were the trial flanging of the mild steel used for the sandboxes and the saddle tank, particularly the formation of the joggle sketched where the tank plates overlap. Trial rivet formation, used in producing the rivets for the main frame angles, a trial pressing of brass sheet between wooden formers indicated that the technique could be used in making the steam and exhaust pipe covers which have to fit snugly to the steam chests and smokebox. Unusually, in the case of these covers the second trial piece was found to be of sufficiently good standard to be used in the finished model !.

JIGS AND TEMPLATES

Jigs will be required to locate parts for some of the operations such as milling and silver soldering. Time spent in producing a simple jig will be repaid by the ease and speed with which the most difficult operations can be carried out. Jigs, used to locate parts in their correct position, do away with the chancy set-ups which are sometimes attempted, using odd bits of metal or wire to hold pieces for soldering, or the sometimes makeshift clamping arrangements to hold metal during machining. A simple jig permits work to be carried out accurately with the correct application of cutting force or allows brazing to be done whilst avoiding the odd movements whilst the metal is being brought up to heat for jointing.

An example of a simple jig is that used whilst soldering the components of the exhaust pipes for Pixie.

A piece of stock mild steel from the scrap box was marked out to replicate the position of the bolts fixing the exhaust pipe flanges to the cylinder casting. The key points of the set out were transferred using calipers and scribing lines on marking blue. A further piece of mild steel was welded centrally to provide a mounting for a bracket which in its turn secured a piece of studding to locate the junction piece where the two pipes join. The exhaust pipes passed through the flanges and were cut to the correct profile to seat onto the junction block. The whole of the jig was oxydised to prevent the flanges becoming soldered solid with their supports ! The flange bolts and those securing the two parts of the junction block were also oxidised. The exhaust parts were thoroughly cleaned and flux was applied before being assembled into the jig. The assembly was made using the preprepared bolts. The joints were then made with one heating, sure in the knowledge that the flanges of the finished components would match the fixing holes and the assembly would seat properly without strain.

Whilst discussing jigs, ties and packing are worthy of mention. For accuracy, jigs must be securely fixed to the bed of a machine. This will be facilitated if suitable tie bolts and packings are handy. It is well worthwhile assembling an assortment of lengths of studding to match tee-nuts suited to the tee slots in the lathe saddle and vertical slide as well as the bed of the milling machine and rotary table if available. Time will then be saved when securing work for operations such as boring and fly-cutting. Studding for the purpose can be purchased relatively cheaply from the trade, tee-slot material can be bought by the length for machining in the home workshop. Short offcuts of bar should be marked with their size for quick recognition and set aside for use as packings. Marking using a punch on the end of the stock will avoid problems caused by the local ' upset ' arising from the punching operation. Often trade suppliers sell such offcuts by the kilo containing a range of useful sizes which are ideal for use as packing pieces.

Templates were produced for the machining operations on the horn castings, the drilling of items such as the steam chest covers, the drillings in the steam dome bush, the foundation ring and the cylinder covers. LBSC's advice was followed in the course of the platework and plumbing. A stiff wire was bent around flanged plates to give the width of plate required. Similarly, wire was also used to establish the route of the pipework and when re-straightened gave the lengths of pipe required. Templates were made for any offhand turning such as that for the cylinder covers, dome, chimney base and so on, ensuring that the required geometry was attained. time spent in thinking through jigging operations and the provision of templates will be amply repaid in ease of operation and the avoidance of scrap.

CHAPTER 7

Frames, stretchers, horns and axleboxes. Wheels, axles, crankpins and quartering. Coupling rods and bearings. Brake hangers and blocks.

Pixies frames and a start on the motion

MAKING A START

So now the time has come, to make a start on machining parts for the locomotive we have so carefully chosen and, on visits to site, measured, photographed and generally fussed over! In the workshop it will be necessary to make constant referance to the database, A plastic folder will hold and preserve the measured sketches from survey and our sketches pertaining to the parts to be tackled. A sheet of perspex in front of a striplight can be used for viewing transparencies which are clipped in place using butterfly clips. It also makes sense to provide some means of retaining photographs of the relevant pieces so that they can be viewed without being handled with ' workshop hands '. A piece of ply with some criss-cross tapes as used to hold letters in an hotel foyer will enable the photos currently in use to be displayed on the workshop wall.

Whilst your subcontractor is casting the wheels from your patterns it is a good thing to make a start on the frames. Handling the raw steel for a 5 inch gauge locomotive gives a good impression of the eventual size and ' heft' of the finished frames. Our supplier came up with a length of ' Black steel '. This has an extremely tough surface and is quite difficult to work. Luckily, in this case , a friend undertook to surface-grind the material and it came back shining bright with the hard crust removed. It can prove helpful to carry a small file with you when you visit your supplier, if you are in any doubt about the workability of materials, a few strokes of the file ( on the metal! ) will tell a great deal.

Regarding thickness of frame material, whilst this may be accurately scaled from the prototype it may prove advantagous to beef-up the frames somewhat. Those on Pixie are from material which after surface grinding worked up to just over 5 / 32 inch thick which is in line with Martin Evan's recommendations for 5 inch gauge locomotives in his ' Manual of Model Steam Locomotive Construction'

MARKING-OUT

The first and perhaps the most critical operation is that of marking-out. The tools for use in marking out frames are basic, a square, a clearly marked steel rule, a good true straight edge and a sharp scriber ( the latter two items can be home produced ). If a marking die which comes as a laquer to be applied by brush is used, the coating thus formed can, with care, be scribed lightly to make an impression without actually marking the steel. Remarkably the lines thus scribed can be ' felt ' using the tip of a sharp centre punch and will guide the punch to points of intersection where a punchmark is needed. An automatic punch which can be adjusted to make various depths of indentation and accommodate differing surface hardnesses is a useful tool. The blue can be left on the metal until all necessary machining is completed then wiped away with a rag soaked in methylated spirit. Where heat is generated whilst the blue is on metal the marks may require some stronger treatment such as a rub with emery cloth or wire wool.

Marking-out is best carried out using running dimensions, as used in the survey, to mark stations along the frames. Running dimensions are taken from one datum in each case and avoid build-up of dimensional errors and consequent innaccuracy likely to be encountered where a series of discrete dimensions are used. The square is used ( from a true edge of the frame steel ) to mark perpendiculars and then dividers or a calipers to set up offsets from the base line. Perhaps it goes without saying that the initial set-out should be checked for errors, it would be a pity to spoil valuable metal and waste valuable time by errors in setting out.

Care must be taken at this stage to establish the centreline of the axles in their running position, both vertically and longitudinally, centre pops either side of the eventual position of the horn openings will provide a means of establishing the axle position and determining the cylinder location, inclination and so on when the actual centre will have been machined away.

CUTTING METAL

Frame steel usually requires cutting to both length and width, a hard job but one made easier by rotating the hacksaw blade through 90 degrees in the frame and mounting the frame material in the vice together with a stock bar to act as a guide.This substantial stock bar inserted into the jaws behind the frame steel acts as both a guide for the saw and a stiffener retaining the long materials Aword here about the number of teeth on the hacksaw blade, and the blade tension, good quality blades generallybear a lael indicatingthe thickness of metal they are designed to cut. Selection of the correct number of tethmakes all the difference to tthe ease, or otherwise of the tsk in hand. Once the blade has been brought to initial tension about three complete turns of the thumbscrew generally suffices to set the correct blade tension. incorrect tension can be recognised when a cut starts townder from the ' straight and narrow '. One last thought on technique, for years we will have been tutored to use the forefinger of the hand gripping the handle pointed forward, ' to guide the cut ' in the case of a wood saw. This action courts disaster in the case of the hacksaw, as the finger is liable to be the first point of contact with raw mtall in the case of blade breakage ! Long cuts such as those required for the frame profiles give time to think out the next move as well as providing some exercise to counteract some of the less energetic workshop activities! With the nett length and width established the frames can be cut to profile. A fairly recent alternative to all this hard work is offered by the trade, in the form of laser cut frames. There is an added bonus in this approach as the supplier will spot most of the holes ready for drilling. Accounts in the model press have been extremely complimentary about the prompt an acurate service offered by the one or two lazer-cutting specialists.

The front and back plates follow, again sawn to shape. Where shapes such as those required on the front plate are required, these can be produced by chain drilling and subsequent sawing. The profile of the frame members can be tidied up by draw filing and all is then set for detailed marking out of holes positions for rivets, horns and similar details. The side frame members should be bolted together at this stage using countersunk headed bolts (countersunk to allow the material to be layed flat on the bench for marking out, and more importantly flat on the bed of the drilling and milling machines during subsequent operations )

At this stage the key lines of the motionwork should be established, for this purpose the frames may be coated in marking fluid from behind the front plate to the line of the back axle or some stout paper glued in place. The first line will be that of the axis of the cylinder which will be set to coincide with the centre of the driving axle at its running position. This line established, the location of the cylinder block can be set out and the position of the slide bar indicated. The motion plate fixing holes can now be spotted with the motion plate normal to the slide bars. The critical angle of between the axis of the cylinder and the top of the steam chest can be measured and a template prepared for use in setting up that casting for machining at a later stage. All this is done using dimensions taken during the site survey. Later the critical sizes of the connecting rods, the valve rods and the piston rods will be established.

A JIG FOR THE WHEEL CENTRES

At an early stage in the marking operation it is well worthwhile taking time out to make a simple jig to the dimensions of the wheel centres. This jig can be used to mark the wheel centres on the frames, to locate the wheel bearings and to replicate these centres exactly when making the coupling rods. Having set out the wheel centres and drilled pilot holes in the jig, it should be hardened and set it aside for future use.

DRILLING THE FRAMES

With all holes marked out and punched they can be spotted accurately using a centre bitt. This is followed by drilling using a succession of bitts up to the required, final size. Any slight innaccuracies can be corrected at an intermediate stage by drawing wrongly placed holes by centre-punching the edge of the hole on the edge to which the drill bitt has to be drawn during one of the intermediate drilling stages. Often the correct procedure for drilling holes, that of using a series of drills up to the finished size of hole, is omitted. Where this procedure is followed the opportunity for correcting the occasional wrongly positioned hole is forfeited,also the finished hole, unless reamed, is likely to be oversized.. On frames of this size it will be advisable to add further bolts to hold the frames together as work proceeds.

Horn locations can be spotted and opened out by drilling and sawing, finishing with a file or by milling. With only two pairs of horns to cater for in the case of an 0-4-0 filing is not too arduous a process!.

FRAME ANGLES

Whilst standard mild steel angle was used for the frame angles they were trued up by milling along one outer face to render them ' die square' to ensure that once they had been rivetted into position, the joints between frame members came up square. The angles were rivetted to the frames taking care that the top of the angle steel was quite flush with the top of the frame members.

BUFFER BEAM AND DRAG BEAM

These were cut from the same material as the frames, somewhat overscale but substantial. The positions of the holes for rivets were spotted through from the frame angles whilst the whole assembly, frames and beams were held together by instrument makers clamps. The actual erection / assembly process was carried out on the bed of the lathe to ensure absulute accuracy of plane. On PIXIE as distinct from many standard gauge locomotives, the head of all rivets on the beams are countersunk. This was replicated on Pixie as were the rivet heads described earlier. There are a number of holes in the beams which give witness to various modifications made during service, although surveyed these were ignored at this stage but will be incorporated later to add to the authenticity of the model.

FRAME STAYS

The frame stays on PIXIE are castings, these are reproduced by fabrication to save the time which would otherwise have been spent in making patterns. The flanges and fillets were shaped, pinned and held together with wire during silver soldering. Having learned the technique,silver solder is generally used to join items where strength is required. A word here about silver soldering. When first starting model engineering great difficulty was experienced in obtaining sound, clean joints.Fortunately however, a friend arranged for a brief training session with a dear old ' Gent ' in the local engineering works. He emphasized the importance of degreasing the materials to be joined, and the need for an adequate source of heat as well as the conservation of this heat by strategically placed firebricks. " Watch the flux," he said, " When it liquifies, touch the solder to the metal and see it ' flash ' into the joint! " Among other tips which he passed on in the course of the brief session was that of making small centre pop marks on surfaces to be joined. The slight raising about the pop mark ensures a minute space between the two parts being joined into which the molten solder is drawn by capilliary action. The solder always flows towards the hottest component in the joint, a point which will prove of assistance when making a difficult joint. For pickle, follow Ted Jolliffe's advice in MODEL ENGINEER and use a solution of citric acid crystals in water. This is generally as effective as acid pickle and far safer to have about the workshop and safer in disposal. The crystals can be obtained in any shop specialising in home brewing equipment.

Many narrow gauge locomotives have distinctive frame details, in the case of PIXIE it is the stiffening angles at the top of the side frames, attached by prominent, large diameter rivets. Having had difficulty in the past with forming rivets to any degree of consistency, and, realising that the results achieved here would greatly effect the final appearance of the locomotive, it was decided to fabricate the rivets.The formed end and shank of the rivets were turned from mild steel rod. The formed end was held in place using a conventional ' Snap ' whilst the shank was peened into a countersink formed in the dummy cone head. In the case of the ' rivets used to fix spreaders between the frames, these were in fact bolts with their heads turned to rivet profile. The cone head was made seperately, tapped to suit the thread on the shank and the fixing was made by tightening head using a specially made socket spanner, furnished with a pin which registered with a hole in the cone. A miniature tommy bar assisted in the tightening process and prior to final assembly the threads were annointed with locktite ' screwfix '. Elswhere on the frames, such as at the angles connecting the beams with frame members, standard black iron rivets were used, the shanks being peened into countersunk holes in heads, again produced seperately but drilled and countersunk rather than tapped. on completion of the peening processs, the ends of the shanks were and filed flush with the face of the ' heads '

HORNS

The axles on PIXIE run in heavy, sprung axleboxes, riding in cast horns. Consultation with Peter, a mine of information, at that time major domo at Messrs Kennion, in Hertford, revealed that some gunmetal castings, which they held in stock, would provide suitably shaped material which with further additions by silver soldering and subsequent machining could be made to replicate those on the full size locomotive. These operations were carried out, prior to the aquisition of a milling machine, on the lathe using a simple jig to assist in work holding. It seems that we amateurs do not make enough use of jigs and fittings, so much a feature of full-size practice. Where we need two similar components, and especially where there are four or more items then construction of a simple jig is well worthwhile, not the least from the safety aspect. Record has it that, in the course of machining materials for an earlier locomotive, one part flew out of a makeshift attachment and left the workshop through a ( fortunately open ) window. Jigs and fittings may take time, they can frequently be fabricated from scrap, and set aside, can often be re-used, albeit with some modification, for further work of a similar nature. Some tasks simply cannot be done without jigs or fittings, for example, to attempt turning a wheelset to size without a suitable mandrel would result in failure. Many other jobs will benefit from the time and thought employed in producing similar simple tools.

At this stage a start was made on machining the horns, the worst of the rough texture of the casting having been removed by filing, the outside face of each was cleaned up by facing cuts made using this tool with the horn mounted in the four-jaw chuck. A tungsten carbide tipped tool is kept specially for such operations, it is a rugged tool produced for a lathe much more substantial than the Myford. It is set on packing blocks under the holder intended to retain tools in the Myford ' boat ' nd is capable of giving castings big licks, provided that is that they are securely fixed! The flat face produced in this fashion was then used as a datum whilst bringing the castings to finished thickness. Centrelines were established and the axlebox openings milled to slightly less thaan drawing size, some work with a fine file squared up the radiussed internal corners left from the milling operation. It was now necessary to solder onto the bottom of each horn a flange piece for later attachment of the hornstay. A jig was made to facilitate the final machining of the horns, it consisted of a backplate which could be mounted on the vertical slide ( those with a milling machine can of course use a similar jig ), fitted with a pad of steel representing the axlebox and having a cover plate which in effect formed a flange retaining the horn in position. Each horn in turn was set onto the jig whilst the bolting face of the horn was machined back by the thickness of the main frame members. The horns were then reversed on the jig and a small diameter end mill used to tidy up the back faces, around the fillets. Each horn was filed to shape and drilled, again on the jig, for the bolts which secure it to the frames. These bolts must have the heads thinned down. Although the slight recess in the back of the wheels provides ample clearance with the axles in their running position it has to be remembered that the completed wheel sets have to be assembled onto the frames and full-sized heads would prohibit this.

EQUALISATION

Consideration was given to making working springing. It was decided however to use the simple suspension achieved by the use of a hard rubber block as adopted on ' Sweet Pea'. Dummy springs were milled from brass block, these were enclosed in a fabricated band of mild steel and the whole drilled with a clearance hole for the tie rods which are screwed into the axleboxes. In practice the rudimentary springing arrangement serves the purpose of keeping all four wheels in contact with the track, at least on my track, described later, which is portable and can thus be packed to a good level when being set out in the garden. The spring mounting brackets were machine from the solid, again by milling in the lathe.

ON MILLING

Considerable amounts of milling work can be carried out in the lathe. To obtain the best results it is worth investing in a substantial vertical slide, preferably one incorporating a swivel action. Lateral support for the vertical slide can be taken from the tailstock quill and for heavy work the slide can be packed up from the top slide. Even without a vertical slide, a lot of useful milling can be done on materials either secured to the topslide using steel packings and strong clamps or in the case of smaller items clamped in the lathe tool holder. A range of end milling cutters and slot drills will prove useful in forthcoming operations. Contact with a local engineering works may yield a supply of used cutters which although past their useful life in the course of rigourous production work can prove useful in the amateur workshop.

As a result of the ' crick in the neck' resulting from time spent viewing the milling cutter at work on material held in a vice on the vertical slide, that the decision was made to purchase a milling machine! A visit to the Model Engineering Exhibition afforded an opportunity to compare machines, and prices. Fortunately for the model engineer the exhibitors often make special offers on equipment and tools at the exhibition , and many are prepared to quote a special price if approached. For the occasional light machining that I was contemplating, a imported machine appeared to fill the bill, and as the price reached after some discussion, and comparison with other suppliers, was within my budget one was duly purchased.

With care in mounting the work, controlled application of cutting force, the use of sharp tools and other simple precautions the machine has proved to be a good investment. I also use it in woodworking, for grooving, routing and so on. It is invaluable as in the construction of hollow masts for model yachts, and similar tasks.The collet chuck is essential in achieving rigidity by reducing the projection of the quill from within the head of the machine. In the absence of an autolock chuck it is advisable to ' key ' cutters into the collets to avoid draw-out of the bitt during the cutting operation. As in all milling operations on such light machines it is important to avoid step milling, or moving the material being machined in the direction of rotation of the cutter, with the tendency of the cutter to climb onto the work. Either of these actions whilst using a light machine are likely to result in snatch with the possibility of damaged tools or worse! . Purchase of the milling machine called for a rotary table and a kit of parts or completed table which has proved quite adequate for the task is marketted by an advertiser in MODEL ENGINEER. Purchase in the completed form, saved valuable time which I could spend in model engineering, this saving more than outweighed the extra cost of a fabricated table. The table has been a great help in many instances from the finishing of valve spindle forks to simple dividing. When rounding ends of connecting rods and similar operations it is important to hold the work securely, and to rotate the work against the rotation of the cutter, failure to observe this rule can result in snatch and possibly injury.

AXLEBOXES

The axleboxes were made in two stages, a phosphor bronze bar sufficiently long to yield four individual axleboxes was machined to a tee-shaped section, the main stem of the tee, being a few thou' wider than the horn openings. The limbs of the tee formed one pair of flanges. The axleboxes were parted off using a slitting saw on a simple mandril in the three jaw chuck. A further phosphor bronze plate was then prepared to form the second, inside flange of each box This method of construction whilst, on the face of things appearing laborious, permits a good fit to be simply achieved in the next operation, that of filing to an individual fit in each hornblock and ensuring a good slide fit between the cheeks of the hornblock. The wearing surface so formed was filed slightly convex to avoid binding when the axleboxes move as the rubber springing blocks become compressed as the locomotive rides innacuracies in the track. The second flange face was now fixed into position using countersunk screws. Each axlebox was next drilled and bored to suit the silver steel used for axles, oilways were cut in each bore and the lubrication holes conveying oill to the axle and to the axleboxehorn surfaces were then drilled.

WHEELS

The wheel castings were in grey cast iron, and remarkably free from casting sand which, if not removed, can quickly take the edge off tools. The castings were mounted in the four jaw and the back face turned until the wheel thickness was .03 inch more than the required finished thickness of the wheel at the boss. At this stage the recess in the back of the wheel, noted during the survey, was machined. This recess provides clearance for the heads of the bolts retaining the horns in the frames. With the back turned to profile the central hole in each wheel was drilled, first with a centre bitt then using successively larger bitts to the stage where it could be reamed to final size.

A plate mandrel was now built from materials from the scrapbox, a short length of 1 inch diameter rod and a disc of mild steel slightly smaller in diameter than the flange dimension of the wheels. The rod formed a stout chucking piece to be gripped in the three jaw and was set to protrude through the plate in order to provide a mounting pin for the reamed wheel bores. The mandril having been turned true its outer face was lightly relieved so that the wheels would bear only around the edge. Care was taken to avoid any fillet at the root of the pin, which would have prevented the wheel casting seating properly. The mounting pin was drilled and tapped, using only first and second taps, and slit so that, when a bolt was inserted and tightened to the extent of the thread, the wheel casting would be firmly located and prevented from revolving under the force of the cutting tool.ith some wheel patterns the existence of a through hole, or the space between spokes may allow the insertion of a stud to further prevent the wheel turning on the mandril. After the mandril was inserted in the three-jaw a reference mark was punched on the rim coincident with the centre of No. 1 Jaw. During the following operations a watch was kept on this to ensure that it had not moved. The mandril was not disturbed until further work on all the wheels was finished. The mandril has now joined the various jigs, collets and templates retained for future use.

Each wheel in turn was mounted on the mandril, face outwards, for the flange to be turned and the tread coned. The old chestnut that coning allows for differential travel of wheels on a curve has often been debated, whether it does or not it certainly assists in maintaining an 0-4-0 centred on the track and may well reduce the tendency of the locomotive to yaw. Here we are reminded of report of the Board of Trade Inspector, Captain H W Tyler on the Talyllin Railway of September 1866 regarding the 'horizontal oscillation' of the one locomotive available to steam the line. 0-4-0 locomotives, particularly those with short wheelbase and substantial overhangs are likely to 'oscillate' and any means which may help to reduce this tendency is welcome. Recent reports in MODEL ENGINEER describe the free running of coned wheels compared with those having parallel treads when set to ' freewheel ' down a curved gradient, another item of food for thought. Coning completed, the radius between the tread and flange was turned using a tool ground to the correct form, the flanges were rounded by filing, (using a file with a proper handle ) and the chamfer put onto the edge of the tread using a sharp tool. Prior to removing each wheel from the mandril, the retaining bolt was removed and a final light cut was taken over the boss. A line was then lightly scribed across the centre of the wheel and the boss for use in locating the crankpin holes. In order to drill these holes, accurately located and perpendicular to the face of the wheel, each of the wheels were supported on two parallel pieces of stock bar in the drilling machine. A hardened drilling jig with an accurately located guide hole was located onto a fitted steel pin, set into the bore of the wheel and clamped into position with reference to the lines scribed whilst the wheel was on the mandril. Each hole was then drilled in the drill press and subsequently reamed to suit the crankpin, the reaming operation being completed on the same setup.

. AXLES

It was convenient to use silver steel for the axles, as discussed earlier the stock size selected approximated to the scale dimension. The axles were sawn slightly over length then, after turning to nett length, centres were formed in each end for subsequent turning operations. PIXIE has plain axles with just two shoulders, one bearing against the back of the axlebox, locating the axle transversely, the other acting as a spacer bears against the back the wheel. The shoulders and bearing surfaces were turned and, after re-touching the tools with a stone, brought to a fine finish. As the wheels were to be fixed using retaining fluid, the axle seatings were machined to leave a full thou' of clearance within the reamed bore of the wheels. Later the joints would be further secured by pins pressed into holes drilled half in the wheel casting and half in the axle

CRANKPINS

Crankpins are of silver steel with turned shoulders to determine the length of projection. Here a slight departure from prototype was made, the outer end was drilled and tapped to permit a separate retaining flange to be screwed into place. In the case of the model Pixie this permitted the marine type bearings to be made in one piece with a dummy joint face as described later. In service the heads are secured by a touch of retaining fluid on the screw as it is turned home into the crankpin. The crankpins are secured by pins pressed into holes drilled half in the wheels and half in the crankpins. This is particularly important in the case of the crankpins on the rear wheels, to maintain the truth of the return crank setting.

QUARTERING

A variety of methods for quartering wheels have been described in MODEL ENGINEER over the years and choice must be a personal thing. The wheels for Pixie were quartered using twin plate templates accurately squared-up as a pair, bolted together, and holes drilled and reamed at the axle centres and crankpin positions. Holes were drilled at each corner of the plates for tie bolts used to drive the wheels into position on the axles. These plates were used in conjunction with a turned stub-centre of the same diameter as the wheel bore mounted in the tailstock Jacobs chuck. The centre was located in the tailstock chuck to facilitate access to the tie nuts in the next operation. The crankpins were first fitted into the wheels, using LOCKTITE, the bond being reinforced by a pin fitted into a hole drilled half in the crankpin and half in the wheel casting. One wheel of each pair was set onto its axle using locktite and the joint allowed to cure. The axle with the one wheel ( and with axleboxes installed!) was then positioned within the ' jacking frame ' formed by the two templates and the four jacking screws. The previously turned centres in the axles engaged on the point of a standard lathe centre at the headstock whilst the tailstock centre was engaged into the previously machined stub centre. At this stage the loose wheel, whilst supported by the stub centre had its bore slightly engaged on the axle end. The bottom edge of each of the templates was packed up, on a common bearing plate, to ensure they remainded correctly aligned in the next operation, that of feeding the wheel into place on the axle. The exposed bearing surface of the axle where the wheel was to seat was annointed with LOCKTITE as far as the shoulder and the nuts on the tie rods were quickly tightened, taking a few turns on each in rotation. The wheel was thus transferred from the stub centre into its correct location against the shoulder on the axles. Accurate quartering was ensured as the crankpins were correctly located by the plate templates which were retained in position by the carefully levelled packings. Once the LOCKTITE had cured each wheel was secured onto its axle by a pin, half in the wheel and half in the axle.

On reflection the work could have been simplified by using a smaller centre slipped into the tailstock sleeve, this would have supported the axle without the need for the roduction of a stub centre. Whilst the first described method worked satisfactorily, it is typical of the model engineering hobby that improvements, or at least modifications of method occur in the course of an operation. This is one of the reasons that the journals devoted to model engineering are so valuable, they form the forum for the transfer of ideas and new improved methods and are akin to the commercial concerns research and development department!

Last updated 25 February 2011

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