thinning tube

Buy it 1/6 smaller than what you have

On Sun, 02 Mar 2008 23:29:38 +0000, Peter Fairbrother wrote, in impeccable English,..

Start with a shed half a mile long.

Ray

Ah ha!

What I actually want to do is make a neck in the tube, ie make a short part of the tube much thinner, perhaps in the lathe using some type of round-nose pliers and lots of grease to squeeze it down, while the rest of the tube remains the original diameter.

Any hints, etc?

-- Peter F

Peter

I am not sure that I understand - do you need a thinner wall thickness or a reduced o.d.? If it is a reduced o.d. consider: the following

How long is the piece you want to neck? If it is only a few inches long you "might' be able to do it in a press as rifle cartridges are necked. Several sets of dies and lots of annealing will be needed. If that doesn't work there is always rotary swaging but that isn't normal workshop kit, and I have no idea who would do it in the UK.

Good luck

ellis

Reduced OD, from about 1/2 " to about 1/10 ".

As it's inconel, and the reduction is large, I'd guess rotary swaging is what's needed.

Thanks,

-- Peter Fairbrother

You could try heating and pulling whilst rotating. Thats how glass tube can be necked down iirc. If you've ever made detailed models think of streching sprue for raido ariels etc. Of course you'll ned to get it really *quite hot* for inconel.

Dave

Turn up that bit separately and 'nail' it to the tube?

Henry

I've not tried this but would a pipe cutter with the blade and rollers replaced with something more suitable do?

Also casting my mind back to that video of that fellow who made his own valves. He seemed to use a device to neck the glass that rotated one end of the tube and rotated the other end slightly slower. Obviously some serious heating would have to be applied in your case, but former could be used to get a good finish.

Graham

A possibility if you have a solid bar would be to use EDM as a two part operation. A simple die sinker ought to work, with one shape turned to the external and the other to the internal. (I did something similar on steel, just to see if it would work, using a local college machine)

You might want to drill a hole previously so that you can improve the flow of dielectric to the internal shape.

Machining the electrode (graphite / aluminium / copper) should be a lot less difficult than machining the Inconel!

Adolphe Sax? It's not as OT as you think.

Ferrees Tools comes instantly to mind!

My wife plays contra bass clarinet, contra alto clarinet and bass saxophone. As Morecombe and Wise put it 'Not necessarily all at the same time'

It's only lateral thinking! And I know a world authority on steam engine loco gears who mends the things.

Cheers

Norman

Wasn't that in the Andre Preview interview when Eric murdered IIRC the Grieg and said: "I play every note, but not necessarily in the right order."

Black 5s with Crapotti valve gear?

Regards,

David P.

David P,

'And one man in his time plays many parts' King John and Henry IV Part one ?

You can't tell me that 'model engineering' is your only forte?

'A poor life this if full of care, we have to no time to stand and stare'

Cheers

I wonder if you were to turn a some plain wheels for a knurling tool and try that- I suppose it depends on the material and its thicknesss.

The original question was 'how to thin tubbing' or 'swage it out'. It was a situation which has been developed over the centuries- and I had sufficient knowledge to be able to pinpoint where the sellers of the best repair equipment was situated.

Everyone else- went off a tangent. Use the information or don't- Sans Feree anne to me.