/diy/ - Do It Yourself » Thread #894146

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45KiB, 350x350, sphere.jpg

Anonymous Tue 27 Oct 2015 15:04:29 No.894146 View Reply Report Delete

Quoted By: >>894155

say i wanted to make pic related for the top of a tesla coil or a vandegraff or something
i could just about do 1/2 on a lathe but how do you do the other half and close it back down again?
is it just cast like that? or pressed in some incredible machine?

Anonymous

Anonymous Tue 27 Oct 2015 15:23:35 No.894155 Report Delete

Quoted By: >>894161

>>894146
Large thin globes are manufactured by "spinning"
on a lathe...
https://www.youtube.com/watch?v=xtEfTSC1PKc

Anonymous

Anonymous Tue 27 Oct 2015 15:24:41 No.894157 Report Delete

Quoted By:

I'm no machinist, but I would bore some regular round stock clean through with the chuck jaws holding the outside of the workpiece. Gave it off nicely, take the time to make sure it's true, and take a few light cuts to give a true outer surface. Then I would chuck it up with the jaws on the inside of the trued bore you cut earlier. Then cut your radii. Flip it over if you need to, but it would be harder to true up the second time. So I'd try and use a double sided cutter.

Keep in mind that I have literally zero machining experience. I just watch a lot of videos. So my advice may be shit.

Anonymous

Anonymous Tue 27 Oct 2015 15:28:03 No.894161 Report Delete

Quoted By: >>894166 >>894170

>>894155
thanks, this is what i meant about doing it on a lathe, i'm not going to cut it i'm not a lunatic.
every time i see this done they fold it around a form and i have never seen more than half a sphere done.
is it easy enough to fold it right over and how do you get the form out again?

Anonymous

Anonymous Tue 27 Oct 2015 15:39:28 No.894166 Report Delete

Quoted By: >>894172 >>894173

>>894161
They either make 2 hemispheres and weld it or...
they use a break apart mold that allows them to remove the mold from the inside of the spun 4/5 of a sphere...

And as you can see metal is quite plastic so given the right circumstances it will "fold over" as you put it...

Anonymous

Anonymous Tue 27 Oct 2015 15:42:41 No.894170 Report Delete

Quoted By: >>894174

>>894161
I always through tesla coils are toroidal. And I can vouch for spinning

Anonymous

Anonymous Tue 27 Oct 2015 15:44:42 No.894172 Report Delete

Quoted By: >>894174

>>894166
I found a nicer video that is using a CNC Spinning lathe...
https://www.youtube.com/watch?v=xhH1Z1s6uoo

12" and 24" spheres are used all the time for architectural purposes. I would check ebay or try to find a local vendor. If that does not pan out try to find a Chinese vendor at Alibaba

Anonymous

Anonymous Tue 27 Oct 2015 15:44:44 No.894173 Report Delete

Quoted By:

>>894166
cool thanks
i'll have a think about a breakapart form and see if they will let me have a go with it on a metal lathe. can't be that bad for the toolpost can it?
my welding is need practice

Anonymous

Anonymous Tue 27 Oct 2015 15:48:08 No.894174 Report Delete

Quoted By:

>>894170
....oh yeah.
shit.

>>894172
that is hot

Anonymous

Anonymous Tue 27 Oct 2015 15:49:13 No.894175 Report Delete

Quoted By:

with the right tools... you can do all of it on a lathe

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