Whilst I have only done it half a dozen times for items in brass and copper I was amazed at how easy it was as long as you continually anneal the blank.

Ages ago I watched a short clip on telly showing a metal spinner who made it look extremely easy!  TalkingPictures show old ‘Look at Life’ and short industrial training films: it was in one of them.

What I remember:

• Big lathe
• A hefty woodworking style rest with a peg, not a toolpost
• The tools were about an inch in diameter and two or three feet long, allowing the operator to apply a lot pressure.
• Don’t recall any lube.
• Nor any mention of annealing, though that must be essential.   In the film, the blank was simply chucked up, and opened out with a few hefty sweeps.   The effort looked considerable, done by a sturdy man applying plenty of leverage.  Don’t remember what the item was, bowl shaped about a foot across, maybe for a brass band.

I suspect if I tried it, £500 quids worth of metal would be crumpled hopelessly in a few minutes!  Bernard’s comment is encouraging though – I should try it.

Dave

The only thing I know about metal-spinning (and why I’ve never tried it) was a graphic description of the personal damage that can result from a spinning disc coming off the machine related to me by a chap who was involved in making copper hot water cylinders. So be careful!

Although I have seen various videos that make it look ridiculously easy…

Rob

Another one who has only had the need to do it once. Steel just over 2″ dia with a 3/8″ return. Think it was 22 or 24g

I turned a hardwood former and held a ring spanner in thetoolpost and used the hard chromed convex part of teh ring as my tool.

I have needed deeper cups a couple of times but took DC’s option of turning to about 1mm thickness from solid, then put it onto a wooden former to finish turn to 0.5mm thick wall and base, this one is stainless 303

A soft grade of aluminium or spinning brass may be easier than steel. This is a nice deep piston spun by a pro from spinning brass that came with the castings

That commercially spun one was certainly a soft brass, you can see a few bits of swarf on the tool holder where I had to true it up, curly not the chips you tend to get from the harder brasses.

As you have cited me – for which I thank you for the compliment – I should amplify that.

It was not a “boiler plate” as such but a plate for covering the boiler’s lagging. It is made from thin sheet-steel, ex-domestic-appliance material.

It is eight inches diameter with a half-inch flange so the amount of metal-distortion necessary is relatively low.

Also, this was done on quite a hefty lathe, a Harrison L5, in lowest gear; so not too excessive a load. The feed was entirely by hand using the rack and pinion saddle drive.

Conventional lathes are not made for spinning, and although they might accept rare, small items in thin, soft metal it is not good to do it very often. It puts quite unfair loads on the machine, heavier than in normal turning. Proper spinning-lathes are much stronger for their diametral capacities.

I would not have tried it on the Myford lathe even though it will accommodate that diameter in the gap.