metal spinning mirrors

Nick,

I'm not a metallurgist, so I can't say definitively if different metals react in different ways, however, I can tell you that when metals like silver and brass get work-hardened, you anneal them by heating them cherry red and quenching them in water. This I have learned from reloading rifle and pistol cartridges (the case mouth can get work hardened from repeated loading and crimping) and from doing some amateur silversmithing. Both processes (handloading and hammering silver) definitely benefitted from this annealing procedure.

Hi Nick

Normally metal spinning is done between headstock and tailstock, the way you are doing it is very dangerous imo.

Only deadsoft alluminium and pewter are not work hardened, gold silver copper brass and alluminium are work hardened. you need good lubrication while spinning or you get the galling that you got.

I think that you should use pewter for what you are trying to do, it's a lot easier to work with, copper also works well and is less costly and can be annealed easily.

The book: "Turn a bowl with Ernie Conover" has a couple of pages devoted to metal spinning.

Here are a couple of links to metal and metal spinning sites, you should be able to get some more info there.

SNIP......

============= If you're looking for "near pure" Aluminum, try to find some 1100. We used that for calculating penetrating power of diagnostic X-ray systems. It's over 99% pure Al. (Seems that I remember it having trace amounts of copper.) I think copper would be a better metal than Al, since it tends to be more malleable, and I think that's what you want in spinning.

Ken Moon Webberville, TX.

Copper is a good choice. "ductility" is what counts. Then electroplate for your mirror experiment. easy enough.

1. The aluminum in hardware stores is probably 1100 (99% pure aluminum.)

1. It was probably in the annealed temper.

2. Regardless, you followed an appropriate practice to anneal it. If you got it red hot, it would have melted. Quenching in water is not required.

1. Because you got fair results with shallow bowls. I conclude that you should do an intermediate anneal after partially spinning the deep bowls. Hold for 2 hours at the highest temperature that your oven will attain.

2. I have never spun metal on a wood lathe. Here's what Dave Hout did on the Woodturning show on DIY network to spin aluminum: a) made a male form and attached to the headstock. b) made a small "tail block" and attached to tailstock. c) centered an aluminum disc between the two. d) used a vegetable oil lubricant. e) buffed to a shine.

1. I recorded the show. I will E-mail a copy to you, if you like.

2. You may wish to try aluminum closer to 1 mm rather than 0.3 mm. The appeared to be about the thickness that Dave Hout used, but I couldn't really tell.

p.s. I have been an aluminum metallurgist for 40 years.

Ken has it right. I turn wood, plasma cut metal and turn and mill metals. In my Metals Handbook - phone book size and about a USD$ per page (ugh!)

I try to be safe.. I use overalls, gloves and a full face mask and I never move past the spinning disk in case it spins off. I figured that if I secured the disk to the mandrel securely (big enough washer and bolt) everything should be ok. Touch wood, I've never had anything weird happen yet.

Nick

Thanks for that info Jim, and everyone else who's replied. I had a good baking today of a disk for a couple of hours and it seems to have worked. I've got 80% through the job before I've stopped it and I'm baking it again. It seems that you are right. I just need to anneal it a few times to get the job finished.

I called the shop where I bought the aluminium today and they didnt have any info on the type of aluminium so I must assume its as some of you said 1100. I also rang a metal supplier I've used in the past for bit of copper on occassion and the sales lady actually asked if its for spinning which I was happy about. It seems that there is a local spinning business nearby which uses either 5005 or 1100 aluminium. A 3 foot by 6 foot sheet of 1mm 5005 runs in at $58 so I might need to pick some of that up as I'm not going to have enough of the other, and then I'll be able to do some comparison of the two.

The only other thing I did today was to increase the washer used to affix the aluminium dish to the mandrel. Its an unusual way to spin it I guess but without a very large swing on a lathe its a bit hard to use a tailstock. At least my ghoulies are firming up a bit!

I'll keep the group posted about the results.

It'd be great if you could email me that video of what dave hout did Jim. My email is snipped-for-privacy@yahoo.com

Thanks very much Nick

I wonder if using a steel tool would be more efficient, and allow forming your shape fast enough so you wouldn't need to anneal more than once. Use the same spoon shape or a full-round bullet shape, highly polished, with wax lubricant. Give it a long handle, so you can use your body to manipulate the tool and apply more pressure. You might need a secondary tool on the inside to help keep the unspun metal from buckling. My wood lathe in it's former life was a dedicated metal spinning machine. It came with a toolrest consisting of a 1" square by 10" long steel block, with several holes on the topside for leverage pins.

Ken Grunke