Fowler Build

Dear All,

I am new to this forum so apologize if I am asking questions already answered elsewhere.

I have just started building the Fowler road engine from Plastows drawings.

My main reason for building is for the engineering side of things and I am fairly confident that I can handle most operations in making the various components (except the boiler).

However I have no experience whatsoever in assembling/building a traction engine so I know I will have many questions regarding the technicalities of actually putting it together and would like some help/advice/pointers if at all possible.

So first up...

Where is the best place to get the boiler made?

The foundry at Bridport suggested "Bell Boilers" or AJB Engineering however I cant reach either of these. Are there others that can be recommended?

Second..

I am starting on the smoke box and front end as well as the tender. Does the smokebox to chimney need sealing to prevent leaks? If so what would you suggest?

Thanks in Advance for any help.

MrT42

Tony Baldwin of AJB has retired and he was also Bell Boilers, as when I rang him the caller id said Bell Boilers. What scale is it?

Rather than worrying about leaks you should really focus on getting started. Things like that can be solved when it's finished. If you're doing it odd evenings and weekends you're a couple of years away from it being finished.

Edited By Robin Dufton on 26/06/2021 20:23:51

You would do well to join traction talk forum, can take a while to get approved but usually not as long as it can take to get a boiler made.

I'm assuming its one of the larger scale ones if steel boilered, you could also try John Rex, again not the easiest to get hold of and they all have quite a long waiting list so best to get that on order as soon as possible so you have it ready when needed.

Foliac is often used for the chimney/smokebox joint.

I would second Jason's suggestion of TT, there is a strong miniature prescence on there. On the boiler (assuming it is a larger one and steel?) you could also try Holt boilers, now run by a Mr Kirk I believe, I know nothing about them apart from seeing them mentioned a few times. There are a couple of other options too if you dig around a bit. Normal wait for a boiler from order to delivery these days seems to be in the region of 18m to 2 years. As mentioned by others though there is plenty to do in the meantime. I would caution completing the tender before you have a boiler as boiler making is not a precision activity generally and you don't want your tender being too wide / narrow to marry up! Wheels are probably a good place to start, plenty of work in them! If you can stick at making the wheels you have a fair chance of completing the rest! Plenty of half started engines out there where people lost interest part way through! I started my current build end of 2016 and it's not there yet!

Paul.

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Thanks for taking the time to reply.

I have registered on TT forum but as you all say just waiting to be approved.

Forgot to mention in the OP that is a 3 inch scale. Good tip re the tender.

I too am building a Fowler miniature, an MJ 3" A7 in my case. I would second the advice from Paul above: don't make anything non-trivial that touches the boiler until you have the boiler.

Now I've just had to google what "dreckly" means, and I think I should add that my progress is distinctly dreckly. I hope you do better!

Martin (daveypaxman on TT)

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At 3" you can go either way as copper can start to be a bit week and steel a bit thick walled. Like the MJ the 3" Plastow one was originally designed with a copper boiler in mind but steel is an option for both and quite a bit cheaper, not sure if Bridports do a steel drawing or just the copper one so that may be another point to consider if you need to find a boiler design.

Edited By JasonB on 27/06/2021 07:59:00

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I know several MJ 3" Fowlers that have been done in steel despite them only doing a drawing for Copper, as I say it's on the limit for whats practical strength wise.

A 3" copper one will be a lot more than that, the 2" is over £2 now from Helen, likely to be rolled from 4mm copper so apart from material cost more work involved too. The other advantage of going for steel is you can get the pressure up a lot higher which will help with the R3 being a compound.

The smoke box has to be a good fit to the boiler so if a spacer ring is used between the boiler tube and smokebox then that can be adjusted to marry the two major parts. You can't size the tender width till you have the boiler.

What you can make without a boiler is,

All the shafts and both axles (just leave them a little long at each end)

Fly wheel

Road wheels

hornplates and bearings

gears

Basically anything that does not require a specific width.

Sealing the chimney/smokebox, automotive exhaust paste ! but more important when steaming is the fit of the smokebox door to the smokebox, poor fit = poor steaming ! (due to loss of draught ) Noel.

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When I did the calculations for the Ransomes boiler I also worked out the yield stress for Haining's copper design and it was below the 2x test pressure, something like 11bar without looking at my notes, vs 12 or so. The yield stress for my steel design is at 40bar and it would reach it's UTS at 70bar. At working pressure the sides between the stays moves outwards by 5 microns, it could have just about passed a 16bar 2x pressure test with no stays.

We settled on 8bar, even though it could have been run at 15-20bar, as we made the pump to his design so it seemed like a reasonable compromise and it is 30% higher than the copper design anyway. We could have redesigned the pump although we've changed enough of the design already.

Edited By Robin Dufton on 27/06/2021 15:35:58

Nice to see some common sense on stay spacing there Robin instead of the usual hysteria! As Jason said steel for the 3" for the OP makes far more sense than copper.

Paul.

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There seems to be a lot of pearl clutching when it comes to steel boilers. I've seen it in old model engineering books that a steel boiler should be 1/4" thick with no evidence to back it up other than best guess or rule of thumb. Our boiler could be 0.27mm thick and take it's working pressure, plus 1mm for waisting, so 1.27mm total. 3mm is plenty. The ASME regs, which I found after doing my calcs and sending them to the boiler inspector, backed up my calcs.

The only thing the boiler inspector questioned was using 3mm thick steel for the firebox and he requested 4mm. I'm happy that 3mm would be fine, although it is 4mm as we're not going to argue or upset anyone, especially someone that experienced and helpful.