In article , Harold and Susan Vordos says...

If all else fails, and it's important to swage the tubing down, you could
try pulling it through a die, then trimming it, or it can be reduced with a
complex setup of rollers set in soft jaws in a three jaw chuck. The chuck
might be mounted on the tailstock side of the cross slide, concentric and
parallel with the chuck mounted on the spindle, and should not rotate. The
stationary chuck is slowly tightened down, with the material rotating
within, with the rollers shrinking the tubing against a mandrel to control
finish size. Not good for long lengths, but adequate for fitting lengths
together if they don't need to telescope great distances.

Avoid aged (heat treated) aluminum if possible.

If only a few thou of shrink is required, and the tubing is moderately
thin walled, one can do this in a (non-turning) lathe with a lever
type collet closer. Put the tubing in the collet, and snap the closer
down on it. Unsnap it, tighten the closer a bit, and snap it back
down. Continue until the tubing is at size or you need to go to the
next size down collet.

Caveats:

1) lube the collets OD before doing this

2) you need to have collets that go by 64ths, basically

3) use your oldest collets.

4) don't do this in harold's lathe....

Jim


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