On Sun, 16 Dec 2007 12:05:03 -0600, Don Foreman
wrote:

On Sat, 15 Dec 2007 23:05:10 -0800 (PST), wrote:

I have to replicate some brass tubes that are used in a carburetor.
The tubes are .093 OD, and .015 wall. The original tubes are 2" long,
with the end .250 reduced down to .067 OD, which has an ID drilled and
sized to .030. I know that I could solder and drill the .093 tubing
and make it work, but I need to make this just like the OE tubing, so
I need to know if this is something I can do in my lathe? I need to
do about 25 of them for the first run.

If anyone can shed some light on this procedure, or has any positive
and helpful comments, please share!

A sizing die might work, just like making little bitty wildcat
bottleneck brass cartridges -- 3 caliber! Might need two or three
dies.

For larger ID I would make a mandrel from drillrod, lube it with case
lube or lanolin. Make some smooth rollers for my scissors-type
knurler, perhaps with a taper on one side for the transition region.
Grab tube and mandrel in a collet, etc. But an .030 mandrel will flex
unless you can contrive a tailstock support of some sort, maybe a bit
of drillrod with a lubed .031" hole in it that goes in the tailstock
chuck.

You may need to anneal the tube before starting.

Let us know how you solve this one!


The easy way is to take your basic copper tubing cutter, remove the
blade roller, replace with a smooth one wacked out on the lathe, then
simply spin the tubing, while tightening down the tubing cutter on the
tubing until you reach your reduced OD.

Quick, easy and repeatable.


Gunner