Making a 2" half sphere from sheet metal

[Futterama]

First quick try, not much success, need to adjust some parameters, including a harder mandrel, the hard wood I found was not that hard after all

Tolerances, shape and finish are not super important, I just need to be able to solder the two halves together.

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[Oldnek]

what if you try to make a female die and use a tow ball, or golf ball, to form it.

[leoitch]

Originally Posted by Charlie Myres

Good advice from Bill!

Copper can also be quenched when it is still red and remain annealed. If you use a quenching bath with, 1 part sulphuric acid, to 10 parts water, all of the black scale will be stripped off; then wash in clean water,

Cheers Charlie

hmm... remember to use full facial protection if quenching in acid. would advise quenching in water and then dunk into acid for a few minutes... much safer.

[AllyBill]

Without making some tough tooling and stretching the material that job is going to be tricky with that steel. Can you weld? You could make it in a few small pieces then planish it over a ball bearing.

Will

[mark g]

Starting with an oversized blank will add radial resistance to the punching force, and will tend to draw the wrinkles radially from the center more.

It will then also require more force.

[Futterama]

Originally Posted by mark g

Starting with an oversized blank will add radial resistance to the punching force, and will tend to draw the wrinkles radially from the center more.

It will then also require more force.

So what does this mean for me? I did not fully understand what you just said

It took very little force to make the failed one, I looked at the pressure gauge, it didn't even move, so I have plenty of force available

[billfunk29]

Would it help to put equal spaced puckers in before pressing?

[AllyBill]

Might be easier to begin with a piece of 45mm dia pipe and heat-shrink it over a tool.

[Futterama]

Did a little wood turning today, it's hard mahogni, kind of stuff used for doorsteps.

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[mark g]

Originally Posted by Futterama

So what does this mean for me? I did not fully understand what you just said

It took very little force to make the failed one, I looked at the pressure gauge, it didn't even move, so I have plenty of force available

Hi Martin,

Sorry for not being clearer.

I'm just suggesting to start with an oversized piece of metal, so that the metal has more resistance to being pulled into the die. The metal will tend to "draw" better and with less puckering. Then trim to finished size after.