metal sheet spining

[Ante]

Hy people

Is it anybody try to spin stailess steel metal sheet (for example tickness 0.5mm) to produce displacer / displacer chamber

some restrictions of this process?
of course it is necessary to have lathe

Salute Ante!

[Chriske]

Hi Ante,

Not quit sure what you're trying to say. Could you explain a bit.
I did some sheetmetal spinning in a lathe quit often. Pressed between the chuck and the tailstock some octagonal piece sheet metal. Purpose is to make these small pieces perfectly round.


Chris

[Ante]

I am talking abot this process:

http://en.wikipedia.org/wiki/Metal_spinning

[Chriske]

Ante,

This is indeed a very nice way of making objects. I have a small movie (how to).
I'm not sure if this technique can be used to make a displacer. I'll try it one of these days.


Chris

[Ian S C]

Chriske, I'm not sure about the annealing of stainless that would be needed as the spinning proceeds. As with any forming of metals to this degree the metal tends to work harden, and this must be relieved as you go, or else it will crack, and break up. Aluminium, and copper are the easy metals to spin, Stainless is sometimes pressed into the form of a cup. Ian S C

[Ante]

In attachment I put some idea about mandrel and finished piece for displacer chamber with flange. I don't know is it taper of side walls necessary.

this is link:
http://www.stanford.edu/group/prl/docum ... inning.pdf
they say that austenitic stainless steel 201 and 301 are very good for spinning.

What is your opinion about mandrel material and lubricant for easy removing finished piece?

Salute!

[Ante]

answers for all questions I found in attached pdf :)
sorry :)

and salute!

[Ian S C]

For a mandrel that shape, a metal former might be best, for something shorter, and thicker a strong wooden one may do. When I get back to the workshop, I must try some experiments, I,v had a sore leg for the last month, and it will be maybe another month till I can stand long enough to do any thing (DAMN). I have doubts about spinning a cup as deep as the diagram Ante. The one I need next is 38 mm bore X 50 mm long, so it might work. I was going to make it from tube, and TIG weld an end on it. Ian S C

[Ante]

Hi

Ian SC my sorry for leg

This process looks very interesting and I hope that someone will have success with this process.

If someone had success with metal spining write!

Salute!

[Ante]

I tried metal spining of stainless steel

Idea was to make displacer end caps from 0,5 mm SS (304)
mandrell is made from wood and sheet clamped with screw.
forming tool is made in second try of brass. (In first was roller bearing)

problem is that outher edge of steel sheet goes in oposite direction (moving away from chuck) and hardenes very fast.

few pictures:
http://imageshack.us/photo/my-images/83 ... 0258f.jpg/
http://imageshack.us/photo/my-images/21 ... a0287.jpg/
http://imageshack.us/photo/my-images/60 ... a0285.jpg/

Any sugestions?
I have two explanations and I am not sure what is correct,
-I am not applaying enough force
-heat influenced on edge because I cut sheet with grinder

Salute Ante

[Ante]

Hi

obviously I need to change method of making end caps for displacer, please can someone give me tip how to make end caps for thin pipe.

Salute!

Ante

[Ian S C]

The motor I'm working on at the moment will have a steel hot cap made of tseel tube with 1 mm thick walls, and an end welded on of 1 mm thick steel (ideally it would be stainless, and may be at a later date), I'v got to take it round to a friend who has a MIG werlder. I would like to develope a spot welder to do the job.
Another way is to cut a disc of similar material to the tube. Make the disc about 1/4" larger in diameter (make up you mind if you want it inside or outside the tube), now find a bit of steel the right diameter, clamp the disc and the bit of steel in a vise, and hammer the protruding edge of the disc right round , working gradually until the edge is a shallow cup shape that will either fit neatly in or over the end of the tube, then braze it in place with the highest temperature alloy you can manage. This system is also good for the hot end of the displacer.
For thin stainless steel, down to .5 mm/ .020" a TIG welder is the way to go, but its getting to expert opperator level ( I'v got another friend who is a profesional TIGer).
The way I made the first four stainless hot ends was to machine them out of solid stainless bar, two made from 2" dia 316 stainless bar, 3" long cost about $NZ30, about 90% went out in the rubbish. The hot cap of this type, I make with a thread cut inside the cap, this screws on to a mild steel cold end. A lot of work (and swarf). Ian S C

[Ante]

Thank you Jan
I did not try jet to form cap with hammer. That is simplest way to get cap.
But I was thinking on similar way, cap with lathe is complicated to make and expensive, and relatively heavy.

JAN do you have any experience how much would last aluminum cap (0.8mm) on hot end of displacer on wood fire 280-300°C ?


Salute Ante

[Ian S C]

I'v made 4 stainless hot ends on the lathe, I started with a bit of stainless bar about 3" long, and 2 1/2"dia, I bored it out to its working size of 1 3/4"a nd cut a thread in the open end, then made a mandrel to fit it firmly (drill a hole through the mandrel, to let the air out, and put the displacer on the mandrel with a drop of loctite, then I turned the outside down to give a .020" thickness, and faced the end to a similar dimention. I put on my welding gloves, heated the stainless, and pulled, and heated and pulled, thought it would never come off. The first 1/2" at the open end was left at full dia, and 3 shallow holes were drilled to take a C spanner. The end of the mild steel cold end was threaded 32TPI to fit the hot end. Ian S C

[Ante]

thank you very mutch for advices

I am not expirienced machinist (I boght lathe before few months) so I need lot things to learn.

Salute