Brass spinning

[Matty F]

Metal spinning is yet another skill that I've never tried or even seen done. I want to make a couple of round brass lids. Basically about 3 inches across with the edge turned down about a quarter of an inch, like this:

was thinking of turning a couple of wooden mandrells and put a bolt through. Since the lid needs a handle there will be a hole through the middle. I'd like to hold the bolt with the tailstock somehow. Perhaps just a hole in the end of the bolt will do.

I like the idea of using a rotating tool like I've made for another reason:

winding that along in a metal lathe since that's all I've got. Unless anyone has a better idea that won't chop my arm off!

[Matty F]

Correction:

[Donwill]

Try asking on NG, uk.rec.model engineering. They are pretty clued up on all aspects of machining techniques. Don

[Donwill]

Should be "uk.rec.model.engineering" An extra dot. :-) Don

[Andy Dingley]

It's not that hard, and it looks scarier than it is. I did a bit, then outshopped it to a local place that made minesweeping floats for the Navy. Huge things, in non-magnetic phosphor bronze. I just liked watching someone who was really good at it, rather than hacking away at it myself.

I think a woodturning lathe is probably a better start than a metalworking lathe. You need woodturning to make up the formers anyway. The variable speed drive is handy. Chucking is often done with a wooden pressure pad from the tailstock. You do need the mongo toolpost rests and they have to be rigid. My wood lathe is nothing like rigid enough, so I had to make a new toolpost that clamped onto the bed and was tightened with a real spanner, not just a quick-clamp lever.

Annealing is an issue. Aluminium and copper are OK, but alloys like brass are more troublesome for work hardening. I think it's usual to avoid the usual brasses and go for gilding metal instead.

AFAIR, there's a good website out there - a lab tech at some US university.

[Matty F]

"uk.rec.models.engineering" But this is not a model, it's a steam engine 20 feet high!

[Matty F]

I couldn't find much under "brass spinning" - mostly companies who want me to pay them to do whatI want to do myself. I only have a large metal lathe, so I've already mostly made the tool that I hope to use. It's a 25mm steel ball that rotates in a 20x40mm holder that I can clamp in the tool post. If it works I can make larger spun objects too. I can turn wood in the metal lathe. When spinning I may use a faceplate rather than the 3 jaw chuck.

[1501]

There's a few examples of metal spinning at Youtube

[Skipweasel]

You could do worse than google for "metal spinning" videos and watch half a dozen of the more promising ones. I suspect it's one of those things that once you've seen it done, most of the mystery evaporates and it comes down to practice.

[Skipweasel]

Ahhhrgh - videorays!

[Matty F]

Some of those videos are frankliy horrifying, e.g. clamping a large metal sheet into the lathe while it's spinning, putting a gloved hand on the rotating work with its ragged edges, taking the work out without stopping the lathe. I won't be doing any of that. The CNC videos show the tool that I want to make. The rotating wheel needs to be bigger diameter and thinner than the one I've made, to be useful as a general purpose tool.

[Thomas Prufer]

I recall helping on a nibbling machine that had an attachment or tool for the bend you showed: A circle of metal (stainless in that case) was fixed in a punch mark in the center, and run through a movable jaw. The nibble machine pounded away at the jaw, and one turned the disc of material while tightening a screw at the bottom to slowly bend the edge of metal to 90°. I was there to disengage the drive on the nibbler when then bend was done, i.e. the third hand.

Thomas Prufer

[Matty F]

I'll try to do the spinning with my new tool I made today:

's sittiing on the sheet brass to be spun. The ball is about 1 inch in diameter. I should have made it 2 inches in diameter and thinner, butI hadn't seen the CNC videos when I started making it.

[Andy Dingley]

pic.com/34q1h92.jpg

Looks scary. I wouldn't use it.

There are two issues - first off, it's for toolpost mounting, rather than by hand. Now unless you've some clever haptic lathe, you've lost the manual feedback from the tool, as to the force (annealing!) required to shift metal. You've also gained a clearance problem over the saddle & cross slide.

Secondly it's a ball, not a round-tyred wheel, so you've far less clearance to the sides.

[Matty F]

today:

> Looks scary. I wouldn't use it.

The spinning job I want to do is tiny - just a 5mm lip on a lid:

'm not planning on using the tool for anything much bigger.

[Matty F]

Here's the brass sheet in the lathe, bolted between a metal washer and the wooden mandrill it's to be formed on:

's the spun brass lid: still needs a handle, and a polish. Next time I will try annealing the brass. I didnt have anything to heat it with. I understand that I just heat the brass and quench it with water.

[Skipweasel]

[Andy Dingley]

Obviously he used a brass monkey.

[Dave Liquorice]

washer and

else!

Oh I'm confused now who does one form some thing round on some thing that is triangular?

[Matty F]

Or a mandril: =96noun Machinery, also mandrel

It didn't look right with one L so I added another!