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How to build your first steam loco

in which a modeller decides to build his first live steam locomotive in 16mm scale.

Inspired by an article about building a small locomotive, in the 16mm magazine, he enquires on the 16mm e-group for information and advice on his first engineering project: a coal fired vertical boiler locomotive.
A vertical boiler loco by Colin Binnie
A vertical boiler loco by Colin Binnie
© 16mm association

Andrew S asked:

I have decided to make my self a project — a coal fired vertical boiler loco, using the boiler design from the recent magazine

As I have never made anything before, I think this could be a nice little project, quite simple, and no major parts.

[he posted some photos of his initial drawings]

What is the best place to buy metal for it, steel for the frames, copper and brass for the boiler?

Also, what would be the best gears to use, I have no idea what so ever about gearing.

Any help and tips would be gratefully welcomed.

Many replies were received, explaining where to obtain materials and what to do.

Andrew had trouble finding the correct diameter copper tube, because it was an odd size (62mm dia). He was advised that any nearby size would be OK, and he would have to adjust his plans to suit. 2 1/2 inch tube would be OK. Plumbing suppliers may be a good bet for obtaining copper tubing, but you might need to buy 3 metres of the stuff you want for your boiler — that would make LOTS of locos!

Component suppliers are described in the following sections:
Materials - metal sections, the raw ingredients
Pre-machined parts - Bits which are worth buying in
Further suggestions - wisdom from those who've trodden the path.


www.technobots.co.uk Under the "Materials" section they do a whole load of metal sections (and some interesting plastic stuff as well) and a good range of plastic and metal gears. Its worth having a poke around this site. They do reasonably priced r/c stuff as well.

For other metal sections Folkestone Engineering Supplies) are very helpful and do a good range as well.

Live Steam Models have a "supplies catalogue" (440 KB PDF) listing copper tube, section etc.

Another metal supplier: Mallard Metals

David Bailey or DJB Engineering, advised:

We use all gunmetal bushes on our boilers, Colphos 90 and leaded bronze. all obtainable from:- www.ekp.supplies.btinternet.co.uk
Gunmetal (which is formed from bronze) can also be obtained from www.m-machine-metals.co.uk (try page 16 of their catalogue, under the heading PHOS,BRONZE look for 'continuously cast leaded gunmetal'.

Pre-machined parts

For Meccano gears, try Meccano man; Look under parts then gears. For those who know nothing about gears, the Meccano rage is very simple to use - see John Roger's 'thing' loco to see what could be achieved.

For Safety valves, regulators and lubricators, Roundhouse are recommended for 16mm. They also sell wheels, axles and cranks.

Sight-glasses and blower valves can be obtained from Polly Model Engineering (Look under the Bruce Engineering components section)

For wheels and axles, try Essel Engineering

Mamod type cylinders and reversing valves — try www.dream-steam.com

Alternative suppliers for machined parts include


Making Simple Model Steam Engines
by Stan Bray
ISBN 1 86126 7738
covers simple static steam engine construction and a vertical boilered locomotive.

This book contains a lot of basic construction , and my feeling is that for a beginner building one of these little engines and boilers and seeing the results of ones work running fairly quickly would spur one on to bigger things. And in those moments when nothing seems to be progressing you could have a quick steam up and see your masterpiece oscillating away. Magic!!!!

N.B. The book does contain some typographical errors.

Someone else recommend Lindsay Publications, in the USA. They are reported to be prompt, courteous and professional and humorous. Many of their offerings are quality re-prints of rare and long-out-of-print books and periodicals. https://www.lindsaybks.com

Buiding Simple Model Steam Engines
by Tubal Cain
The engines described in Tubal Cain's books are stationary with oscillating cylinders. The first covers boilers and cylinders from the basics. Each book is stand alone rather than a sequence, but perhaps the first book would be best to start with. Try TEE Publishing,
(Useless fact: Tubal-Cain is the first metalworker recorded in the Bible)


Boiler diameter, go up to whatever you can find. Try to keep the inner flue about the same also the chimney. The chimney size was decided by a number of failures. It did not say in the SMT article but the chimney is brass but is does not matter.

As to gearing, with 32mm diameter wheels and a single cylinder try for a ratio about 5 to 1 reduction i.e. the wheels go 5 times slower than the crank axle for the cylinder. If you go 2 cylinders about 3 to 1 should be OK.

To get the gear ratio divide the number of teeth on the large gear by the number of teeth on the small gear. If there are 2 sets (stages) of gears then multiply together for the final ratio.
e.g. First stage 38T and 29T 38/20 = 1.9 Angle stage 25T and 10T 25/10 = 2.5 total reduction 1.9 x 2.5 = 4.75.

Keith B suggested:

The best place to buy your metal - brass, copper, bronze is a local non-ferrrous metal stockist. Ask to have a look through his offcuts. Take a ruler and caliper with you to measure any pieces you find that look suitable. For steel, you require a steel stockist, but be aware that they tend not to have a stock of offcuts, so you may have to pay full price for a length cut off a piece of bar, sheet or whatever.

I would also be cheeky and ask around at any small engineering firms in your vicinity. Again ask for offcuts, bar ends, scrap material and so forth. I recommend taking along something you are making to show, discuss. Drawings, pictures etc of finished project may help break the ice, but you need to speak to the right individual. Avoid these places that have a clueless female manning(?) the front desk. Ask to speak to the foreman, manager, or whatever.

Lastly, try the scrap yards. Trouble is, you don't know what the specification is of anything that you find, and they may not be helpful. They may not know any better than you.

Roger O suggested:
Metal for boiler. Use bronze/gunmetal for boiler bushes, not brass as brass can lose its strength and crumble through electrolitic or chemical reaction. Brass is fine for fittings screwed into bronze bushes as they (the fittings) are not an integral part of the boiler. For the same reason fittings should not be screwed directly into the boiler. Silver soldering of boiler joints and a pressure test using water to completely fill the boiler is are essential safety requirements.

Model engineering suppliers will stock suitable materials.

John L warned:
Copper tube can be quite difficult to get hold of and expensive too. The only trouble with a coal fired boiler this size is that it will take A lot of attention to keep going, as the loco is so small the boiler will not have much water capacity and the grate will be small.

I would recommend a bigger boilered loco for a more relaxed and successful run, there is nothing worse than spending months on a project that then won't go. I would also say, start with something like a Brazil rather than throwing yourself in at the deep end so to speak! If you have no machining facilities or indeed experience your project is likeley to stall at stage 1. Sorry to sound so negative but I would much rather see a fellow modeller make a decent first engine than be put off for life by a project that was not suitable.

(i.e. keep away from coal fired for your first loco, lest the hurdles cause you to give up)

Doug P suggested:
As a "beginner" the Brazil is a good starting point.

The cylinders may look a bit daunting but once you have made one it gets a bit easier each time.

And Steve T suggested:
Quite a few of you have suggested that Andrew's coal-fired De Winton would be difficult to make. I'm about to disagree (before I go any further I must say that my thoughts here are pure speculation and not from experience).

A while ago, a chap was running a coal-fired vertical boiler loco and said it was dead easy to fire because he could fill the firebox right up to the top. In a regular Stephenson type boiler it is all too easy to over-full the firebox and block the tubes, or under-fill and have the fire go out.

Also, it wouldn't be too difficult to make a multi-tube vert boiler instead of the more usual single flue. The firebox could have dry sides as the grate are would be quite large.

Sounds like a good goer to me. Shame I've already got zillions of projects already .....