rain distillate wrote:Danespirit wrote:CArDbord, does the job too...
Well, this looks like the start of some very enjoyable copper porn...
It's not every day we get to see a turnip shaped still.
You'll have to do a lot of copper bashing to get that shape out of that plate.
Do you envision something like an Alembic form, or will the bottom also be round..?
I'm ready to take my time and have this come out the way I want it too. I haven't decided on an EXACT style yet. I spent 3 hours looking for turnip designs and only saw about 10 turnip stills with no design plans attached.
To get the hammered styled texture would it be easier to hammer the pattern on the sheet before I shape and bend? Or does this pattern come naturally from planishing?
Well, one method is spinning, like others suggested.
Unfortunately, this technique requires a big bastard of a lathe and some special tools to get it done right.
The worst part would be the form tool. However, this could be made out of wood...one would shape a "bowl" form or a half sphere, so to speak.
Then that form would be used to spin the copper plate over, and I mean literally "over".
Another method I have used for a project is to make a bowl-shaped piece of wood (the harder the better, so don't use pine or such).
Then anneal the copper plate (disc) and gently hammer it to shape in the bowl form.Use a nylon dead weight hammer, or you'll stand there hammering when Santa Claus comes by.
This method requires frequently annealing of the copper, as it will work harden as you progress.Planish the two half parts to a desired smooth surface (auto repair shops use hammers like this to do the fenders etc.).
Two similar bowls would form the finished boiler part. Then you just have to decide whether or not to solder ...use rivets..or both.
If it were me, I'd roll a ring out of copper or brass (won't matter as it is supposed to be outside). the ring should be Pi times the middle diameter (this means subtract one material thickness on the outside circumference)
Drill some holes in the circumference of that ring you just made (they should match the rivets or be 1/10 of a mm bigger).
Let the spacing be around 20 to 30 mm, to be sure you get a good connection.
Anneal the rivets and proceed to rivet the whole thing in one way around.Get a buddy to hold against the inside, if you can't reach in and hammer simultaneously.
When you have finished riveting, clean everything around the riveted parts thoroughly.
Apply flux and solder the parts around the rivets.
You'll now end up with a sturdy connection, that is totally leak free and doesn't require any sealant as you want to do a run.
Clean the mess up, you made inside, before proceeding with the next step.
Edit: The video Shady linked to, shows a method with a sandbag made out of leather. If you have one it's the best tool, custom body shops use them, too.
Unfortunately, such things are not standard equipment in the shed at home.
(hes also got a lot of brass inline and no matter how much I bug him I can't get him to remove it...maybe that's why he likes mine so much...its cllllllllean 
I wish you luck on the build. 
