For browsing non-Model Engineers and Would-be Model Engineers who find themselves here and are wondering what it’s all about. I will run quickly through the steps involved in building a locomotive and the equipment you will need. If you are already familiar with the hobby this section is probably not for you!

This is a personal rambling reflection on my own interest in model engineering stretching over a period of 15 years or so, the advice is my own and (arguably) worth what it costs. Model engineering is not my only hobby, I have many other interests including electronics, computers, photography, tropical fish, motorcycles, astronomy, shooting, car mechanics, beer... the list is long (and expensive - especially beer!). I got into model engineering through the back door as it were, I had bought a small lathe (a new and basic ML10) as part of my interest in shooting for the purpose of restoring guns and making reloading dies, and a couple of years later I bought a part finished 2 1/2” gauge locomotive off a neighbour because I thought I could finish it and it would look attractive on the mantelpiece. I had always admired the workmanship in miniature steam engines that I had seen at exhibitions and had a yearning to own one. Anyway, the 2 1/2” gauge loco was a mistake. What was already built was a disaster, dimensions were horribly wrong, the valve gear was a joke, and the boiler leaked like a sieve. Nothing too obvious you understand, but with the experience I have now I would have spotted the problems straight away. It still would have made a reasonably attractive static model but would never be a functional steam engine.

So, I figured I could make a better job than that starting from scratch, and promptly looked around for a suitable model to build. Tich first took my attention - this is a small 3 1/2” inch gauge 0-4-0 contractors loco which is considered to be THE loco for beginners to start with. The advantage was the availability of a complete construction manual by the famous (in model engineering circles ) LBSC. However, I though it was too small, not enough wheels, and I didn’t much like the look of it. I wanted something that looked like a real steam engine. Eventually I purchased a book by Martin Evans describing the construction of an 0-6-0 tank engine called Rob Roy which at least looked the part and I decided to make one. At about the same time, a friend bought a similar book describing the construction of Evening Star, a much larger 2-10-0 tender locomotive which he proposed to build as a first job. He never got further than the wheels! - I think you have to be a *little* selective in what you tackle first.

At this point my selection of tools, with the exception of the ML10 was, shall we say, basic. I had a few files, drills, very few reamers, a micrometer, a vertical slide with vice for the lathe and a few odd end mills. The ML10 had already earned it’s keep for many years doing small gunsmithing jobs, but I deeply regretted not buying the bigger ML7 to start with. The problem of course was cash, but I guess I could have bought a second-hand ML7 for the price I paid for the ML10 new (it was 230 UKP then - about 15 years ago). Still, that little lathe gamely struggled on, I eventually built two locos with it, but it seemed that every operation was stretching it to it’s capacity. Nowadays, there is another option, and that is to buy one of the cheap Asian imported lathes. Arguments have raged (and still do) about the value of doing this - sure, they are cheap, and you get a lot of cast iron for your money. However, I think in the long run the faults inevitably present in cheap machine tools will nag at you and I don’t think you will be happy with it. If you were an experienced machinist you could probably do much to improve matters by modifying the machine, but as a beginner you are going to be out of your depth. I would go for a second hand well-known European or American machine which, after all, tend to last a long time. There are basic checks you need to do to ensure it’s not worn out though so either read up on the subject or get someone knowledgeable to go along with you. These comments apply mainly to the lathe - the fundamental machine in the workshop which has to be accurate. Other jobs are less demanding and I have quite happily bought a cheap imported bandsaw which does the job well. It underlines the fact though - I would not like to see the same faults in my lathe that I see in the bandsaw! I have recently traded my ML10 (a tearful farewell) for a new Myford S7 at horrendous cost (like 10 times the price when I got the ML10). My wallet still has tear-stains and a bandage and splint to prove it.

I think every model engineer starts like this, tools are built up slowly over the years as and when required, so if you have even less than I had to start with don’t worry, as the work progresses you will ‘acquire’ what is needed one way or another. I have to admit though, that it’s not cheap. Buying new tools these days is an expensive hobby and you really have to shop around. I was lucky at one point because I dropped across an old chap who was giving up practical work and selling his workshop contents. I bought loads of stuff of him for very little - he was glad to see it going to a good home where it would get used. I still have (years later) a toolbox FULL of silver steel (drill rod), hundreds of lengths (including difficult to obtain square section) which I got from him. The point is, there are frequently old chaps retiring from the practical side of the hobby from whom you could likely equip a workshop at modest cost. Most would prefer to see their favourite tools going to someone who would appreciate them rather than selling as a job-lot to ‘house-clearance’ sharks. A good way of finding out about potential sales of this sort is through a local club or society.

There are no two ways about it, building your first miniature steam locomotive is a *long* job (count in years to start with). I guess many get started and never finished. You not only have a lot of learning to do but a lot of tools to make along the way. My second loco was bigger, more complex, and took half the time to build as the first. If I continued I might be knocking them out at 6 month intervals but I doubt I will ever reach that enviable stage. The interest for me was partly the challenge of building it in the first place, and partly the desire to own one. If you just want to own one forget buying the tools altogether and just buy a finished loco off someone! If, like me, you drop across a part finished loco which might save you much time, investigate it’s history first, check it’s pedigree - make sure it’s been built correctly to whatever stage it’s at.

You will need persistence. I nearly said patience but that’s wrong, I have no patience at all. You are going to make mistakes as the model develops and some parts are going to get junked because of this. It’s a learning process and things *will* go wrong from time to time. In my case there were many instances when various bits of machined metal bounced off the workshop wall in disgust. I’m talking here not only of making dimensional errors - which is just carelessness - but also machining technique. Trying to cut a 1/4” slot with a 1/4” mill - reasonable? on the face of it logical but totally wrong - it will cut oversize. This is the sort of thing you learn. Luckily, major components (like the cylinders) survived so setbacks were relatively minor. More annoying is when the fault is not your own - there is a famous error in the Rob Roy drawings whereby if you follow the dimensions to the letter (number?) the steam chests end up out of position in the frames. This was the most serious fault but there were many others. Much cursing followed the discovery of each one.

Even though I was following a construction manual there were many things left unsaid. The Tich manual by LBSC is better in this respect as nearly all operations are described thoroughly, if somewhat idiosyncratically. Nevertheless, as a beginner you are still going to be left scratching your head and thinking “how do I...?” at various times and ingenuity is going to be called for. This is good practice because if you ever move into the big league of working just from plans, or even your own scratch-built models, you are going to have to work out machining methods yourself. It’s important that machining operations are carried out in specific sequence otherwise the job will be made much more difficult, or even impossible.

There is much opportunity to show flair, independence, ingenuity etc. When you see a miniature locomotive it looks just right - just like the real thing. It’s not until you see TWO side by side that you realise the differences between 2 models of the same locomotive can be remarkable and yet both look ‘right’ on their own. This is partly in the amount of detail, the painted finish, the boiler backhead etc. I suppose I should point out the distinction between classical ‘glass-case’ scale models which strive to be perfect miniature versions of the original, and semi-scale ‘working’ models where several modifications have been made for the miniature version to run well on the track. Again, this not only involves detail dimensional changes to strengthen important parts, but some things just *have* to be of different design to work properly (for example, the lubricator which supplies oil to the cylinders).

Anyway, if you have never considered building a miniature locomotive, and are intrigued, and are also thinking whether you could build one or not, let me just say that - yes, you probably can. All the skills necessary are progressively learned. The next question is what is the minimum cash outlay that’s needed? I’ll just run through what *I* think you need to get started building an average 3 1/2” gauge ‘beginners’ loco.

You’ll need a lathe for a start. No doubt about it, no getting round it. Don’t think one of those tiny lathes sold by Emco, Sherline, Cowels will do either - get a meaty one at least 3 1/2” centre height, 18” between centres. Bigger if not gap-bed design (i.e., will turn a large faceplate some 9” diameter). The reason for this is that several components are better machined by fixing them to an angle plate attached to the faceplate. You just can’t do this on a small lathe. Also, larger lathes remove metal more quickly, even though the job appears to be within the small lathe’s capacity jobs are far easier on the larger lathe. I haven’t mentioned it before but the lathe needs to be screw-cutting, some very old lathes are not. The screw-cutting lathe is supplied with a selection of gear wheels to be assembled at the headstock (chuck) end which will drive the carriage at a fixed ratio to the turning chuck. Result is that a cut made by a special pointed tool produces a screw thread. More expensive lathes have a gearbox instead of loose gear wheels, quicker for common thread selection but a limited in ways that probably won’t matter to you for considerable time (and you can usually get around it by buying loose gear wheels). The lathe extras you’ll need are:

Vertical slide - assuming you won’t be buying a milling machine, this will give you that capacity. Small machine vice - to clamp to vertical slide. Selection of cutters - end mills and slot drills. These are expensive, if you can’t buy second hand either go for a job lot from cheap tool suppliers, or just get about 4 sizes to start with. 4-Jaw chuck - 6” diameter minimum. I originally got a 4” 4-jaw with my ML10 and it was never of much use. Faceplate - if not with the lathe - 8 or 9” diameter. Toolbits - A selection of 4 of the common shapes of carbide-tipped tools, and a few HSS (high speed steel - tool steel) blanks will be sufficient.. A rotating centre would be nice but not essential.

You will need a bench grinder to sharpen your tools, these are fairly cheap in the 6” diameter flavour, and if you can get one where the grinding wheels actually revolve true and in balance all the better (memories of the cheap grinder I bought - took ages to get the thing to run correctly...)

You will need a drilling machine of about 1/2” capacity. Be careful here, you might get lucky with an Asian import - you might not. Some are OK, a lot are awful. It’s vitally important that it drills square to the table - a couple of dozen speeds are no compensation for inaccuracy. You will need a comprehensive set of drills, it’s cheaper to buy sets than individually as-required, so make your mind up now whether to go for letter/number drill sets (the old imperial measuring system) or a metric set covering the same range. Personally, I have letter/number sets and a part set (0.5mm increments) of metric drills. You will end up buying reamers (an expensive job this) in the range up to 1/2”, you can plan ahead (from the instructions/drawings) which sizes you will need right away. Machine reamers are best as they have very little ‘lead’, and start cutting full diameter from right near the end. You will need a selection of taps and dies - again, look at the instructions or plans and write down all the different threads you see listed in the jobs you will tackle first. These are the ones to go buy. Don’t go for a full ‘set’ as it will never have all those you need and you’ll be buying stuff you’ll never use.

You need a good selection of common hand tools, a good ruler, micrometer, callipers, square, punches, hammers - a whole load of stuff. None of which are terribly expensive on their own but cost a fortune if you buy everything at once. Get a tool catalogue and look through it marking off the stuff you really can’t do without (be selective - I mean really *can’t* do without). Make your list and that’ll do for a start.

Those tools will get you started. If you can buy second-hand all the better, you’ll save a little cash, but lathes (in particular) hold their prices well so your investment will not suffer much depreciation should you subsequently decide to sell up (you won’t though, once the bug bites it bites deep!).

You will need somewhere to work of course - a workshop of some description. With a lathe and drill you’ll need a permanent site. Most amateurs use either the garage or garden shed (or maybe cellar). Mine’s the garage and the car sulks on the drive (got to get the priorities right...). Whatever you choose you need *solid* benching. Look at my pics elswhere on this web site and you’ll see mine are specially made from heavy section planed timber, fitted to make best use of the available space. The lathe is better off on it’s own metal stand, but if you are careful (that means levelling it carefully) you can get away with wood provided the temperature/humidity doesn’t change much. Rather rules out the garden shed where you’ll need a metal base. The reason for this is that the lathe is very sensitive about how it’s mounted, very small inaccuracies in it’s base can cause warping of the bed and it won’t cut parallel. Another reason for having a workshop is that it’s somewhere to mark ‘out-of-bounds’ and can be safely left in a mess (I mean ordered confusion... *I* know where everything is.).

Locomotive Building:

You now have your embryo workshop, tools and you’re ready to start on your loco. Which one did you decide to build? Several strike me as suitable - Tich (see above), Rob Roy (my own choice), Simplex (a larger 5” gauge similar to Rob Roy in design). Thing is, if you haven’t built one before you really need a set of instructions to work from, something that gives you general machining tips as well as information on the loco itself. This is available either as a book (there are not many published like this) or as a serialised project in a magazine such as Model Engineer. The latter can be obtained either as individual back issues (Warning: you may need 1-2 years worth - hardly economic to order back issues, even if available) or they can often be bought as sets. I have bought about 10 years-worth this way for only 5-10 UKP per year and so have serialised articles on the construction of several locos. I should have mentioned Model Engineer magazine earlier as it’s a useful source of all things related to the hobby, and has a very long pedigree. Be warned though, some of the pictures can be very off-putting - you only need to see some of the superb workmanship some folk achieve to get a severe inferiority complex.

I’m not about to reproduce a construction manual here - you will already have one. I just want to add some comments of my own about what are significant steps in the process of loco building.

Having chosen your victim you will need to purchase the relevant castings. In the UK there are a wealth of companies prepared to supply both plans and castings for a wide variety of locomotives. Elsewhere I dunno, you may be reduced to making your own castings, but large companies like Reeves ship all over the world. The loco you’ve chosen will (sensibly) be a common model so you’ll have no problem locating castings. The complete set of castings are (groan) expensive. Luckily, you don’t need them all at once. The first jobs are the frames/wheels/cylinders. Come to think of it - the wheels and cylinders are the most expensive castings...(groan!). Ah well, but in addition at an early stage you’ll need axle boxes, horn cheeks and (well, look at your plans). You could cheat and get laser-cut frames but then you would miss out on the pleasure of biceps-building hacksawing and filing long pieces of 1/8” steel plate. You would also not learn the art of correctly marking out the frames so you are *certain* the holes are in the right place and the outline is correct. This is not the time to make a mistake, all the valve gear, wheels and cylinders are dependent for their correct alignment on you getting those frames correct. A bandsaw is very useful for frame cutting.

Next job is probably axles and axle boxes (and eccentrics if needed). Take care these are a correct fit (you need tolerances in the right places so they move up and down but not side-to-side). The machining sequence ensures they are parallel to each other and square to the frame. The wheels are easy, again if you follow the instructions. Only drawback is the skip you’ll need for the cast iron swarf created. This is filthy stuff, just what you *don’t* want on your lathe bed (it wears it when trapped in the slideways). Use cut card templates to protect as much of the lathe as you can, use a vacuum cleaner to remove all the swarf immediately after machining. Wheels need to be assembled on the axles correctly (known as quartering) so the connecting rods will fit, instructions are given using a variety of methods - I use the lathe.

It’s a pity the cylinders will likely come next - these really need your best efforts and you have had little practice up to this point. You should try to put your best work into these items if the finished loco is to run well. Pistons need to be an accurate fit in the bores, bores need to be bored true and in the right place, dimensions need to be strictly adhered to. Follow the instructions step by step and you shouldn’t go far wrong. This is one of the main reasons I reccommend a beginners loco to start with where these steps are clearly described. Next time you will know what to do.

Connecting rods will come next. These will need a little ingenuity if all you have is the lathe. Problem is that, without a milling machine, you will need to machine fairly long thin bits of steel on your lathe - or file them to shape (yuk). The manual will describe lots of tricks to do this, and how to get nice rounded ends to the rods - so I won’t bother. Your accuracy of working will first be tested when you assemble them on the wheels and see if the wheels still go round.

Things will have moved fairly quickly to this point and your chassis will be looking imposing. Next job to tackle will likely be the valve gear, all those bits of jointed metal sections which govern the valve events. It’s probably about here that you begin to wonder what you have gotton into, especially when you see a long thin rod with a wide fork at the end - how the #### are you supposed to machine that? How do you even hold it for machining? There are 2 choices, start with a much bigger piece of steel and cut everything away that doesn’t look like the rod you are making (this is fun with a blunt end mill and steel section that promptly warps out of shape) or fancy your chances at making the big bit and thin bits seperately and brazing them together. I made all mine from solid - lesser of two evils I think.

At some point you are going to need the boiler. Now, this is a job in itself and you need yet more expensive gear to roll your own. Further, flanged plate sets (well worth the extra cost) and silver solder represent a large proportion of the expense. On balance, I think if you are only likely to make 1 or 2 boilers you may as well grit your teeth and buy one ready made, the difference in cost between that and buying the materials and equipment is not going to be so much. It’s easy to ruin a boiler part way through leaving you to start over. I don’t want to put you off trying but I have to say I bought my first boiler and don’t regret it.

Probably the next jobs are finishing the chasis - brake gear, water and oil pumps, smokebox and so on. All fairly mundane stuff and you will have achieved a certain level of competency by this stage that none are going to cause you problems.

Nest stage is platework. There are new techniques to be learned here as working with sheet metal offers new challenges to work through. There is nothing terribly difficult about it but you need to be accurate marking and cutting out, making nice straight and square edges to the parts, and don’t try to rush the job. You will be left to your own devices a little here as details of just how the platework goes together is up to you. Quite often you can improve things - making it easier to dismatle for example - with a little careful thought.

The final bits of pipework, mounting the boiler and so on will see you near the end of the project. The only problems here are access to the parts you want to work on, things become a little tight where scres need to go in at odd angles and into tight corners (where your hand won’t go).

The very last job is painting and lining the loco, an art in itself. After all, that’s the bit you see - not the metal surface.

PART II ******************

I think it may be worthwhile going back over some of the above steps in a little more detail, perhaps expanding on those tricky machining operations that might pose a problem the first time. I'm trying to remember all those mistakes I made but I'm spoiled for choice.

FRAMES: If you buy frame steel from a supplier together with your castings don't be surprised if it arrives a dirty black colour with a fairly rough surface. This is 'hot rolled' or 'black' steel and for this job it is superior to 'bright-drawn' or 'cold rolled' steel. The reason is that the hot rolled steel has less stress in the metal than cold rolled steel, and the latter is very likely to warp out of shape when you go cutting chunks out of it to accept the horn blocks and cylinders - the hot rolled stuff will stay flat. Having said this, make sure the pieces are flat to start with - return them if they are bent - you will never get them flat again if they are kinked (a small degree of even curve can be corrected but is best avoided). The rough finish of hot rolled steel certainly doesn't make it any easier to mark out accurately. Use marking blue and a sharp scriber to mark out - don't try to make bold marks by heavy pressure on the scriber, it doesn't help much to make them more visible. Many older plans assume 1/8" steel plate will be used for the frames but this size has generally been replaced with the nearest metric equivalent (and they might not bother to tell you). Check carefully for this as the difference, though small, can cause endless problems when you come to assemble the valve gear. You may need to adjust the size of the frame stretchers to make up the difference. Same goes for the buffer angle steel, but here the consequences are not so grave. You really need a surface plate to set the frames square for assembly. The frame plates and stretchers are usually held together by small bolts which allow some degree of 'adjustment' of the precise alignment, so use either the surface plate, lathe bed, a piece of 1/2" plate glass or formica kitchen worktop (in decreasing order of accuracy) to rest the parts on whilst bolting up. In full size practice frames used to be set to a few thou', so scale that down to our miniature size and you can see that acceptable errors are small indeed. However, using the accepted method of machining the frames as a pair (whilst bolted together) and careful control of the stretcher dimensions will produce the required accuracy. It's a good idea to paint the frames when finally assembled, or at least use a couple of coats of anti-rust undercoat. I didn't do this on my first loco and I couldn't face complete disassembly later so they remain un-painted.

AXLES: For 3-1/2" gauge these are usually 1/2" diameter, and I made mine from silver steel. Unhardened silver steel (drill rod) provides a very good bearing surface with low wear characteristics when combined with either cast iron or gunmetal axle boxes. It's important to make sure that the seats for the wheels on the end of the axles are concentric with the bearing surface, so, either use the 4-jaw chuck and set to run true before centering each end, or (as I did) make a split bush held in the 3-jaw ( a method described elsewhere). After centering the ends the wheel seats are turned with the axle held between dead centers. A better alternative is to use a proper 1/2" collet if you have one of course, but on no account rely on the 3-jaw alone to hold the axle blank. A good trick is to drill the centre deeply with a 1/16" drill, then cross-drill the axle bearing with the same size drill. This will enable you to get oil to the bearing surface using a plunger-type oiling can applied to the outside of the wheel center and it will flush out any ash or grit. These days it's common to use Loctite engineering adhesive to attach wheels to the axles. The old method of using a press fit still offers some advantages though, despite the additional accuracy requirement and slightly trickier assembly during quartering. Get the dimensions wrong for a press fit and you can either end up with a loose wheel (which moves under power from the connecting rod) or you can even split a wheel casting if you press it onto an over-size axle. Nevertheless, I still prefer the press-fit together with a locking pin for extra security (call me old-fashioned if you like). The problem with Loctite is that you must be both quick and accurate when quartering - no second chance, and you can never be *certain* the adhesive has got where it's supposed to go, or that some trace of oil hasn't got onto the mating surfaces drastically reducing the bond strength.

WHEELS:

(to be continued when I get time - and if there’s interest!)

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