I'm ready to make the end plate formers for my small horizontal pot boiler. The body tube is 1.625" od, and 1.512" id, thus a wall thickness of .056". I have both aluminum, and oak available for the formers. Are there any hard/fast rules or formulas for making the formers? With either material, I plan to have a center hole for a mandrel to turn them on. I'm leaning toward turning the former out of aluminum, as I have enough copper tube for a couple more.
I'm also making the end plates from pieces of the tube, so the end plates will be .056" thick. What would be the minimum radius for the flange? How wide should the flange be?
I'm following Stan Bray's design Boiler # 1, in chapter 14 of the book "Making Simple Model Steam Engines", but I couldn't find 2" or 50mm tube. I assume the former diameter would be tube id – (wall thickness x2) and the blank disk should be a diameter of tube id + (flange width x2), with some allowance for the radius of the flange bend.
Last question, which is the best orientation for the end plate in the body tube, flange pointing in or out? Why?
Have you thought of spinning the flanges for the ends ? flanges in as then the boiler has a larger volume , as it tube is smaller diameter have you increased the length to give you the same volume ?
Jeff, I've never spun metal. How difficult is it to spin copper?
Can you recommend a setup?
A lot easier than bashing to a former , you have to turn the former in the late anyway just leave it in the chuck , make a washer for the tailstock centre and clamp the copper disk , and run a ballrace at 45 degrees onto the disk it will go down in a wave .
I have a ball bearing 'nudger'. I think I'll try that.
Can I do it with one anneal, or will it work harden before I get it formed?
the end plate material is still in a tube shape, though I have slit both tubes. I'll anneal them and get them flat.
For a 1/4" flange should do it in one but don't hold me to that , a lot depends on the thickness , I have got involved in making 6 Ellie steam trams 2" diameter boilers so let me know how you get on .
Tried the ball bearing nudger... Not good. I ended up pounding with a plastic headed hammer.
Still couldn't get the plate to fit. Then I discovered that I forgot to remove the plate thickness from the former.
After I turned the former to body tube id -2x plate thickness, And worked the plate some more, including skimming the od of the formed flange, it fits!