spin forming for kicks

[Tony]

yeah I don't think this is the 'conventional' way to do it.
i bet the back end of a broken carbide tool would've been better..
i just happened to use the tail of the unlucky indexable tool that happened
to be in the toolpost.

i'm sure if it was heated with a torch like in those videos it would've been
better.

See I was making some big "pegs" to hang belts on.. I had that thin
tubing.. but after parting off the ends were really sharp no matter what
I did (its really thin wall!) .. so I thought I'd just try to muscle it over into
a chamfer.

Didn't take very long (or very much force!) for it to turn red and then I
could just push it around into any ol' shape.

Tony

[macona]

Hot forming is how they do cylinders for gas:



Though they don't rely on friction to heat the metal.

Also tire rims:

[Black_Moons]

I don't think that is standard spinning per say so much as hot forming, Sorta the reverse of those friction drills, Still very impressive results! I suspect its actually not that much pressure on the cross slide because he simply used a dull bit to heat the material until it was easy to form, a slight pressure should quickly build up heat at high enough rpm.. Also preventing the issue of the pipe flying out of the chuck.

That said, I think I would still put a plug inside the pipe to keep it from collapsing while I crank the chuck down hard.. And stay out of the line of molten metal.. And cover my poor ways!

I think one would control the heat with pressure, once it gets bright red you back off and let it cool, then ram it again once its down to cherry.

What are you using as the tool? I would think something like a rounded off carbide insert might work best. (Sand the hell out of an old chiped insert or brazed carbide tool?)

[Mike Nash]

Whoa Tony! I think that is cool!

But I also think "How come the pipe didn't come flying out of the chuck?" But that's just because I'm pretty sure it would have if I tried it.

[Fasttrack]

I think you typically use a special tool (and lathe) for spinning. The tool has a big bearing with a spherical race so the friction between the surface of the tool and the spinning object is greatly reduced.

Edit: http://www.youtube.com/watch?v=um-biLfru-c

[Elninio]

looks like there wasn't enough heat by the cracks in it, how much load does it take on the compound?

[Tony]

Marty: thats a very good question.

I know nothing about metal spinning... How do you keep from heating it up beyond recognition?

[Tony]

then the other way:

[Tony]

I'll be the first guy to tell you there's nothing new under the sun..
but I was surprised when this actually worked.

Tube is thin wall 1" (0.040" wall)