Large Brass/bronze Bowl How To?

[wallc]

I have been trying to figure out how to make a large "firebowl" for a client, and am stumped. I know how to do it manually (cutting shapes and english wheeling them and rewelding peices back together) but the budget does not allow for it. I have thought about sand casting, but the mold would have to be in three or four parts (most likely four) but making the form and then re welding after shrinkage and growth, may also be cost prohibitive. Does anyone know who spins large bowls, a small shop perhaps, or who may recommend a better, more efficiant way to do this? BTW the bowl is roughly 5'0" diameter, by 14" deep, and has a flat spot for sitting, and a turned over lip. Please help, as I have not been sleeping for the last few days, trying to figure this out. I thought I had the smarts-guess not.

[Dema]

I have been trying to figure out how to make a large "firebowl" for a client, and am stumped. I know how to do it manually (cutting shapes and english wheeling them and rewelding peices back together) but the budget does not allow for it. I have thought about sand casting, but the mold would have to be in three or four parts (most likely four) but making the form and then re welding after shrinkage and growth, may also be cost prohibitive. Does anyone know who spins large bowls, a small shop perhaps, or who may recommend a better, more efficiant way to do this? BTW the bowl is roughly 5'0" diameter, by 14" deep, and has a flat spot for sitting, and a turned over lip. Please help, as I have not been sleeping for the last few days, trying to figure this out. I thought I had the smarts-guess not.

Hi wallc . . . ?
The best way to do your bowl is to spin two alf and overflow them together, (not welding).
You have to make a form out of hardwood or aluminium and over them spin it.
I will post some pictures soon.
Dema

[Kerry Pinkerton]

What thickness is the desired metal? Is it brass or bronze? Any special temper?

[Gene_Olson]

if you don't have a budget for wheeling the part, you almost certainly don't have a budget for making tooling to spin it.
Have you added up the cost of the bronze yet?
Have you allowed for wastage? sheets are square, spinning blanks are round.
If you are spinning, have you planned on annealing the material, maybe a couple times. Have you had one of your welds stand up to spinning, or are you going to buy a full mill run of the bronze to get the blank big enough to spin your part?

What is your time frame? (and as Kerry said, material thickness, alloy spec, . . .)

[Doug98105]

"Does anyone know who spins large bowls, a small shop perhaps,"


Check with a few spinning companies that've been around awhile. The old timers will have rooms full of old forms. Maybe something will be close to your design or could be modified to fit.

As Gene said, the cost of the form will blow you away if they have to start from scratch.

Van's Metal Spinning in Seattle is a place I know has tons of old forms, there're probably a few in your area too.

Another thought is too find a shop with a CNC spinning machine, some of those don't need a form.

Doug

[DYCE]

What about a tank company? How do they make the tank ends. I think they are stamped but I am unsure. If they are, and You supplied the material I would think they would stamp it out. Then maybe you could just make a base to set it in?
Jeff

[Gene_Olson]

I'm waiting on answers to the material questions.

I could make it with a bag and wheel, my pullmax and a doming die, hammer and dolly, just plain wheeling, (1" crown in 1/4 plate brass 22" dia in just over an hour of wheeling.)

[bobadame]

How about a casting a concrete form to hydroform over?

[wtowns01]

Here is what I see, if 5' diameter and 14" deep that would mean that you need a 74" min diameter disc. So you would not be able to shape out of one piece of sheet.

If you took a 48" disc and formed that up, then you could take a strip and weld up the rest of the way. Which would be about 200" of welding.

Just not feasible not unless a $5000 plus budget.