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Which scale to build

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Lee Jewell28/04/2019 14:58:07
8 forum posts

My first posting here, but I'm after some advice.

I have inherited my late father's part built 3" Burrell agricultural engine that I intend on finishing off, although it may only ever be a static model due to no paperwork for the boiler.

What I need your help with is, I'm looking for a bigger project for myself once his engine is done. I'd love to do a showman's engine with all the fancy detailing.

I was once told, build as big a scale as possible. Is this actually good advice? Subject to tooling being big enough is it no more difficult to build say a 4" or even a 6" engine as it is a 2" or 3"?

Has anyone on here completed a showman's engine in the larger scales? If so, which plans did you follow? Are the plans detailed? Or did you have to take detailing from a full size engine and scale it down yourself?

Thanks for any advice you can give.

Paul Kemp28/04/2019 18:49:27
422 forum posts
18 photos


Welcome, nice the hear of another potential traction engine builder on here. There are a few but as this is more a general model engineering forum it has a broad sphere of interests, you might find it worth signing up for traction talk as well, more dedicated to road steam and has a very active miniature section.

In terms of your questions; whatever scale you build too the engine will have roughly the same number of parts. In terms of ease of manufacture as you say it depends on tooling available but also your desire / ability in "watchmaking". It can often be easier to make larger parts because they are easier to see and hold! Trouble is as you get older while they become easier to see, they become harder to lift!!

A better way of looking at it maybe is what you intend doing with it when you have built it. If you think you would enjoy taking it to rallies and shows and running it quite a bit then 4" and upwards is easier to manage in terms of firing and water level and more capable of dragging you around on courser surfaces (a lot of rally fields are anything but flat and smooth) and capable of travelling longer distances. If you think you will just use it occasionally in the garden and keep it as a "showpiece" then smaller is more practical for storage and handling. Big engines need proper consideration of how you will move them around, you can't just pick them up.

There are a number of drawings available for Showman's engines in various scales from 2" to 6" probably all of them are not exact to detail so if you want something that is an exact scale copy then it's best to choose a model of which there are easily accessible full size versions around so you can take pictures and measurements to confirm the accuracy of the drawings. Worth also rembering that even two of the same full size engine are unlikely to be exactly the same!

The last consideration is cost. While there is not a big proportionate difference in buying a commercial steel boiler in 4" or 6", the bigger you go requires bigger bits of bronze for bushes and bearings and steel for axles, con rods etc. Bigger rivets need proportionately more force to close and obviously bigger cylinders and flywheels as you have recognised need bigger and heavier machines to finish them.

Not definitive answers I am afraid but food for thought maybe.


JasonB28/04/2019 18:57:53
17800 forum posts
1947 photos
1 articles

The other thing to consider is the size of the prototype not just the scale. A showmans engine base on say a Burrell Gold Medal Tractor at 6" scale will come out around the same size as a 4" showmans based of say a B6 Fowler.

Brian H28/04/2019 18:59:10
1566 forum posts
102 photos

Hello Lee and welcome. You don't say whether the 3" boiler is copper or steel.

I've built 3" and am now working in 1 1/2". 3" or bigger is easier if you have the equipment to work it. You also need to consider how it will be transported; if on a trailer then this will need storing when not is use.

A showmans in 4" is a huge undertaking but if that's what you want then go for it, there's no point in building an engine that is not exactly what you want.


Lee Jewell28/04/2019 19:41:54
8 forum posts

Thanks for your comments so far.

With regard to traction-talk forum. I have registered and confirmed my email, but I still cannot view the posts as my account is awaiting moderator approval.

I think 4" Burrell Scenic from live steam models is most realistic, but as I haven't set up my workshop yet (having been out of the hobby for about 20 years) I'm flexible on size.

I'd love to do the 6" version. But scared it might just be too big an engineering project. I might have to go to a couple of show's through the year and see what is about.

The 3" I inherited has a steel boiler, made back in the 1980s. It's in great visual condition as it has never been filled or steamed. But without documentation, I can't find anyone willing to inspect and certify it.



Boiler Bri28/04/2019 19:50:43
832 forum posts
197 photos

Lee. I am not a skilled engineer so chose the Suffolk dredging tractor for my first build as it was more or less made from flat bright bar.

My second has been the 4" Durham engine. This is nearing completion after a few years. The skill I learned on the first model helped with this one

I have also started a sweetpea loco which again is simplistic.

These are my suggestions.

On this forum there are varied skill levels and everyone is alway helpful - the occasional key board warrior puts his stupid comment in but there easily ignored.

What ever you choose to build I hope you enjoy it. It's a fascinating hobby


Lee Jewell28/04/2019 19:54:40
8 forum posts

I too have a sweet pea. I started it when I was a junior member of a local MES, the design was kind of picked out for me as being easy and a good starter loco.

Unfortunately, I never fell in love with building it as I'd have rather have gone down the traction engine route like my father had.

Paul Kemp28/04/2019 21:26:55
422 forum posts
18 photos


If you can prove your boiler was built prior to 2002, dated photo or witness statement may be sufficient you are clear of one hurdle (CE marking). There remains the issue of material certs and welder qualification but you may find a commercial inspector willing to take it on. If you have some idea who built it that may help. Where abouts in the country are you?

re TT unfortunately David does not have a reputation these days for being a fast mover! Try dropping him an email reminding him you are waiting for approval. If you offer a £10 donation as he has made a recent appeal for funds it may spur him on!


Lee Jewell28/04/2019 21:49:57
8 forum posts

I have a date stamped photo of the part built engine taken at our local MES exhibition. It was late 80s. Good old Olympus OM10 date stamp.

Unfortunately, I have already contacted John Glaze to see if he would be able to carry out any sort of inspection. As there is no paperwork trail, he can't do anything with it. Seems a shame as it was a very well built boiler. But both my father and the welder have since passed away.

So my options are, to build it as a static model or pay for a new boiler.

I'm based in Mid Wales. Don't think there are too many TE people around here. It's mainly model locomotives.

I'll try emailing TT as I'd really love to get on there and see some of the models and get some inspiration.

Paul Kemp28/04/2019 22:16:20
422 forum posts
18 photos


John is not the only option! Boilers have been examined and retrospectively CE marked through RSA so it's not impossible. May not be cheap in terms of weld X Ray's but in terms of confirming the composition of the plate there is technology available that can do that quite cheaply. Where there is a will........ May still be cheaper than a new commercial boiler. If you know who welded it, it may be easier.


Lee Jewell28/04/2019 22:35:26
8 forum posts

I'm 99% sure who welded it, if I'm right he passed away about 15/20 years ago.

He was a welder in a local agricultural manufacturing factory that my dad worked at. I'm not sure there was coded welding back in those days, bur he was a professional welder.

Paul Lousick28/04/2019 23:41:28
1365 forum posts
529 photos

Hi Lee,

As stated, the model of the engine depends on the scale and size of the original. I am building a 6" scale Ruston Ptoctor SD but the original only weighed 3 1/2" ton and the model 700 kg. It will just fit into a 6x4 ft trailer. A good indication for comparing the finished size of different models is the diameter of the wheels. The rear wheel on mine are 24". I chose to build a larger engine because I wanted to ride on it and not to sit on a trailer behind it.

The number of parts is the same for all scales of the engine. You just need a lathe/mill big/small enough to do the machining. For the parts which I could not fit on my machines, I did elsewhere. A bigger engine just neets more material to abuse. Sometimes smaller ones can be be very fiddly because of size.


Dave Halford29/04/2019 13:39:17
682 forum posts
6 photos

Why would the boiler need CE marking? I don't think you could imply a commercial build without boiler stamps.

it would be possible to confirm the materials are to spec at a local big scrapyard or a jeweller that buys gold, but the welder could not be claimed to be suitably coded for pressure vessels anymore.

You could talk to Station road steam, they may be able to advise.

JasonB29/04/2019 13:58:04
17800 forum posts
1947 photos
1 articles
Posted by Dave Halford on 29/04/2019 13:39:17:

Why would the boiler need CE marking? I don't think you could imply a commercial build without boiler stamps.

At the time that was mentioned we did not know if it was home made or a commercial boiler. From subsequent posts it is now in that grey area of having been welded by someone else and did he do it as a favour or was he paid to weld it.

Not sure if the chemical composition of boiler plate is far enough from basic mild steel to be able to test for make up.

Lee Jewell30/04/2019 01:40:30
8 forum posts

At the time that was mentioned we did not know if it was home made or a commercial boiler. From subsequent posts it is now in that grey area of having been welded by someone else and did he do it as a favour or was he paid to weld it.

Not sure if the chemical composition of boiler plate is far enough from basic mild steel to be able to test for make up.

As far as I'm aware, nobody was ever paid cash for the work on the boiler. They all did favours for each other in the factory. But as both parties are now deceased. Proving this would be impossible and I think that's why even a private inspection from someone like John Glaze seems unlikely.

Lee Jewell30/04/2019 01:42:19
8 forum posts

Does anyone have a way of contacting Dave at TT? I've tried emailing him using the address on the page, but it has bounced 😩

Former Member30/04/2019 09:52:09

[This posting has been removed]

Lee Jewell30/04/2019 10:06:30
8 forum posts

Thanks Bill, if you could drop him a message I would be extremely grateful.

So far I've tried emailing that was on the welcome email. And that is on the forum homepage, but both have bounced.

RICHARD GREEN 230/04/2019 17:39:10
310 forum posts
183 photos

Hello Lee,

I totally agree with the view " build as large as you can", but don't be under any illusion, large models can cost a lot of money to build, castings, boiler, boiler fittings, rubber tyres , also tools etc that you havn't already got,

Also large models need large machine tools to build them,

I built the 6" Burrell in the picture, It took me 7 years and was a hell of a lot of work, but all worth it when finished,

I cut the straight gears, the largest was 21", the flywheel was 25" , the final drive gear and winch drum probably weighed around 300 Lb before any machining was done,

The castings were from EKP Supplies in Devon, They do a 6" an 8" and I think some 3" scales as well, have a look at their website.

Any help I can give you, please send me a private message, I am in Bucks,

Good luck with whatever you decide to build,






Edited By RICHARD GREEN 2 on 30/04/2019 17:41:00

Former Member30/04/2019 18:11:13

[This posting has been removed]

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