Hi Everyone

[mancavedweller]

Hi,

my name is Keith, living in Melbourne, Australia, but originally from the UK (just too damn cold and wet).

I've built a cnc plasma cutting table to compliment my other toys - lathe, mill, bandsaw, press, welders, etc. Hoping to one day turn this large and risky investment into an income producer, instead of an income taker.

One of the things I would like to make is ball / spherical firepits with patterns cut in them with my plasma cutter. However getting hold of these spheres seems difficult or expensive. Mind you if I manage to do one metal spinning thing I'm sure I'll end up thinking of a few more things to do.

Perhaps extremely ambitious but I'm wondering what sort of mammoth lathe I would have to build to try and spin 3mm thick mild steel about a metre in diameter. My metal lathe is big enough to machine whatever shaft size I'd need, it's 1.5 metre between centres.

Keith.

[RockHillWill]

Welcome to the Allmetalshaping site.

[weldtoride]

Welcome to the site. Having done some small scale spinning, I would agree, and rate your spinning goal specs extremely ambitious for a home shop. Have you done any spinning at all on a small scale?

Meanwhile, as an alternate plan, here in the US, "tank heads" are available custom made and also in some stock sizes from a number of different manufacturers. Some are spun, others are drawn. Don't know about your part of the world, but it might be worth a look around your industrial formers there.

"Tank head manufacturers" is a searchable term here (substitute "end" for head as well) with loads of results, but maybe they call them something else in your neck of the woods. Lots of our suppliers are near oil and gas processors, and also near ship building yards. At least a visit would show you how big a lathe you would need.

Good luck with your endeavor, sounds like you have a great start on a shop.

[mancavedweller]

Looks like I'm accepted, thanks Will

Thanks for the input Mark. I have done zero spinning before apart from viewing Youtube videos and imagining how it's done LOL. My metal lathe is pretty big so should be fine for seeing how mild steel sheet responds to spinning. Time to read some of the spinning books I've collected too.

After reading your post I messaged a spinning mob and have asked for a quote on two 900mm diameter, 3mm thick hemispheres. Should be interesting.

I would guess tank heads would be more expensive than a thinner spun sheet. Aren't the tank heads sort of roll pressed with powerful hydraulic forming machines.

Keith.

[David Gardiner]

Welcome to the forum Keith.

David

[Oldnek]

Hi Keith, and Welcome

John

[mancavedweller]

Got that quote back but they could only do 800mm hemisheres. Each one would be $265 + sales tax, so $530 + sales tax for one sphere.

When I add petrol, highway toll fee, and my time to pickup, I could safely call the price $600 + tax for a one off sphere. At the price I could buy the steel (i.e. normal retail) there's about $80 worth of steel in those two parts.

I certainly wouldn't want to get welding distortion when welding the two hemispheres together LOL.

Keith

[Jere]

Hello Keith and welcome to the forum.

Jere