Boiler Formers

Hi all,

a bit of advice please, I hope this is the right section for this question.

I am planning on making the Reeves 2-6-2 Prairee in 5" guage. It is a super detailed plan and copies the shape of the belpaire boiler quite well.

The tubeplate is a typical round with a flange and in such cases I have turned a steel former and followed the normal procedure of clamping the annealed plate between two plates, beating reannealing etc.

The throatplate follows typical design with a flanged hole for the taper and an opposite outside flange for the firebox wrapper. The firebox backplate and the backplate are to me unusual in that the firebox back has an outward facing flange for the firehole that mates with an outward flange on the boiller backplate, so no firehole tube.

So there are three plates that have outside flanges in one direction and flanges in the opposite direction. All these are typical belpaire shape.

I have in my mind the method of forming the plates, form the holes first and use that as a register in the clamping plate on a forming plate with a matching male section to hold the plate for forming. So any plate is going to take quite a lot of hammering. I don;t have acces to a steel bandsaw and don't fancy cutting steel formers.

What alternatives are there to steel please? I have a wood bandsaw and router, available. There is a hardwood timber yard not too far away and I have offcuts of MDF but I am doubtful if MDF will be strong/firm enought.

Thanks

There is a super heavyweight density fibreboard available, the offcuts I have had in the past are incredibly hard.

Hi Steve, I'm making a BR Standard 2 boiler at the moment. I got M-Machine to lazer cut all of my flanging plated out of 12mm steel. Check around your location for lazer cutting companies.

For single use a bit of hardwood such as beech should be upto the job, worked for this part. If you can find an offcut of solid wood worktop that will be ideal or even a cheap cutting board

Plywood is fine it will stand up for single use with no problems at all.

And you can use plywood any old bits of softwood and p38 filler to to make formers for the firebox wrapers like this.  If you have a bandsaw you really have no problems.

Edited By Buffer on 27/10/2021 08:26:11

Edited By Buffer on 27/10/2021 08:33:11

Another vote for Beech formers.

I've just read your post again and that fire hole sounds really hard to make to me. Can't you just fit a tube within a tube? I would think trying to flange those holes to line up would be a bit of a nightmare.

Edited By Buffer on 27/10/2021 09:13:37

I used .5 and .75 aluminium plate for my Allchin TE boiler and tender formers, they were also loaned out to another Allchin builder, The aluminium plate came as off cuts which were free,

Digressing slightly, I am about to commence, with some trepidation, to construct the boiler for the Allchin 1 1/2” scale Royal Chester that I am making and I am following this article with interest. I would prefer to purchase flanging plates ready made rather than have to reinvent the wheel so to speak, but I don’t think that they are available, failing that perhaps someone has some that they would be prepared to lend or even sell. I see Peter had his made from 12 mm steel, is this the optimum thickness to use and I am thinking perhaps using M-Machine to fabricate as he did, there aren’t as many engineering facilities here in the South East as there are in the Midlands and the North so choice of suppliers very limited. Dave W

Just seen Nigel’s post which popped up as I posted the above, so Aluminium plate is also a contender. Dave W

I get my steel plate from a local engineering firm that has laser cutting, so that is a possibility. But from the drawings you can see the shape of the plates I have to form.

I like the idea of beech and the local timberyard should have some and as in my previous like I was a joiner I can work it easily and get a good finish. It also means I can easily add extra parts to register the firehole either to fprm it or act as a register to form the outer flanges.

Buffer, I suppose it would be possible, but I like a challenge and as the drawings show a hole centre that gives me a good datum to set out from.

Hole centres.

Side views

Assembled.

I used plywood for the flanging on my Aspinall and 3D printed formers for outer and inner wrappers, which work a treat. I have also used a 3D printed former successfully to reshape one part when I got plywood shape wrong.

Hope the following photos may be of interest to some people.

First couple of photos show the 3D formers.

This photo shows the laser cut and 3D printed drill jig I made to get all the bits in the right place.

Where I am

Trial fir in chassis.

Nigel, I have sent you a PM. Dave W

Dave,

Would it be possible to take a couple of pictures of your outer wrapper to throatplate joint please. That looks like an interesting joint for round top boilers.

Phil H

Phil

The joint is basically as per Don Youngs drawing. The only change I made was to the outer wrapper to include the little 'ears' that line up with boiler tube flange. The throat plate is double flanged, hopefully this picture will explain the joint, note the bottom of the throat plate and the wrapper have not yet been trimmed to length.. If you want more detail let me know.

Take care sawing woods like beech (aka old school desks) as the dust is not good for you

Love the 3D printed formers. I have used ally plate for flanging formers with great success, cnc milled on a Taig Micromill out of 10mm ally plate.

Thanks Dave, excellent picture.

Phil H