Sheet Metal Spinning

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Anyone ever done any sheet metal spinning. This is one of my first completed parts. Its pictured with the type of machined metal part we'll be replacing. I think I could do a pretty cool pommel plate this way. Anyone ever done it?



 
I have thought about trying it, but haven't yet, I've seen video of the process and an old school machinist I worked with for a while had done some spinning. How many times did you need to anneal? What type of equipment did you use? What is the part for? Did you do any finishing? The surfaces look pretty nice, most examples seem to have a better finish than I would expect.

Todd
 
I build antenna systems. I bought the metal annealed. I didn't re anneal at all. This is maybe my 7th try, so its not hard to do. A LOT faster than machining a part. The tools leave the survace with a very nice finish. I did use scotch brite pads a little then a little metal polish. Maybe 3 minutes total for the sanding and polishing while the lathe is running. The part took less than ten minutes to make once you get a mandrell ready. That is just basic lathe skills. I glued up a block of hard maple and cut a shape my boss gave me. Then you just do it up. Its a pretty neat process.
 
I know a custom maker of wooden flutes for Irish traditional music, who spins the sterling silver cups for the keys. Much faster/better than when he previously made them from flat stock, silver-soldered.

Neat stuff!
 
Looks cool. I'll bet you could make a smaller version, slap a leather thong on it, and sell them as saucer amulets at UFO conventions.

What kind of antenna systems do you build, Andy?
 
Andy, excuse my lack of machinists knowledge. I don't understand what the spinning is. How can sheet metal be turned on a lathe?

Can you explain a bit more?
 
Looks like fun Andy. Could you spin me a couple of "C cups" out of brass stock? Cold weather being only months away, the old witch could use a new brassiere. ;) :rolleyes: :D

Sarge

Avast ye swabs, don't be asking me how I know the witch wears a C cup. Tip them rum glasses sparingly lads, tip them rum glasses sparingly. . . . . .:p
 
OK. I build antennas for research projects Josh. Each project is different. I'm the engineer at work who is tool savvy, at least in a minor way.

A viet kong hat would take a pretty big lathe. LOL.

Sarge it would certainly be fun to make the mandrell for spinning C-cups. But it could be addicting, and I don't want to miss my forum time. LOL.

Steve, to spin metal you first turn a part to form the metal to, then pinch the metal between that and the tailstock and use a polished bar of steel to force the spinning sheet metal to the shape of the form, or mandrell. It gives you a hollow metal part. Thats how they do metal balls and goblets, or how they did it before stamping technology came along.

http://en.wikipedia.org/wiki/Metal_spinning
 
Haven't done any spinning, but I have done some raising by hand, including a goblet. It's a month long process of hammer, anneal, hammer, anneal...

For a shape with such a small amount of dishing, I woulda thought it might be even faster to just form them by stamping/punching with a set of two dies.
 
It is. Thats why spinning is a dying art form. Its also uber expensive comparatively, thats why spinning will never totaly die. We're an ultra small company, and can't afford dies, and stamping equipment. But we have a lathe, and can afford some maple. So we can make whatever the big boys can without having to use their expensive process. before we spun the parts I machined them on a manual mill machine. That took my untrained self ~half a day, and if it didn't pass QC... start over. Spinning I can get a lighter part that is easier to solder in ~10 minutes. Thats 24 times faster. Huge improvement.
 
aproy1101 said:
We're an ultra small company, and can't afford dies, and stamping equipment. But we have a lathe, and can afford some maple.
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:D Then you already have the tools to make dies. Hard maple dies should last you for a small run of parts. Our metalsmith teacher once told me to just make the male die out of steel or whatever, and then just mold a lump of JB Weld around the end to form a perfectly fitting female die. (it was an odd shaped piece) This was for non ferrous fine metals- annealed copper should be no problem. We did all the initial dishing and rough forming for our raising projects over a big wooden stump with a couple bowl-shaped depressions carved in.
 
How did you carve your dye? How did you press it? How did you ensure your die was within spec? I wish we had a teacher. Basically all the metalworking I know I've learned on the internet. They don't teach that stuff at engineering school. Most companies will send you out for training, but mine won't. We won't farm it out either. We do everything in house. So when there is an idea basically the entire meetingroom will slowly turn to me and ask, "Can you do that?"
 
I don't think stamping would be as fun. Is it fun?
 
First off, what you're doing now sounds like it's working just fine for you, so I'm not really encouraging you to change. When it's all said and done, I'm not sure you'd save any time for a small run of parts by making sinking dies.

aproy1101 said:
How did you carve your die? How did you ensure your die was within spec?
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Carved the same way I worked other stuff- by hand. Since you've already got a lathe, I'd guess that would be the easiest way for your situation. Or just improvise on the JB-weld method, and lathe turn the positive die, and make up a mold of epoxy, coated concrete, or whatever to form the negative. I'd think the dies would have to be made slightly deeper dished to compensate for the metal springing back a bit once pressure is released. Thus keeping it "in spec" would require a bit of trial and error.

How did you press it? I don't think stamping would be as fun. Is it fun?
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I didn't press it so much as whack it with a big hammer. :D But I suppose you could improvise all kinds of presses, from a big vise or C-clamp, to a common bearing press powered by a hydraulic jack. So yeah, it certainly can be fun. :)
 
I'm sure we'll stick to our method, but that doesn't sound as hard as I had imagined it. I really need a metalworking class.
 
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