On Dec 16, 2:05 am, 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.

I used to spin a reduced neck on 15/32" OD musical instrument tubing
in order to start it on the drawbench by annealing the last half inch,
putting it in a collete and cranking the back end of an old amstrong
toolholder into it. It worked, but it was a kind of dicey process.
Eventually switched to driving the ends through the full series of
draw rings using a rubber mallet. If driving, make absolelety sure to
anneal only the region you are working, or the whole tube will bend!

Don't know how well either process will work at reduced scale.

If you can get an end srunk down smaller than desired, you can try
putting it over a sizing mandrel with a step turned in it, and the
driving through a sacrificial die... used annealed fender washers to
make tapered french horn leadpipes that way. Problem with this method
is that it's very hard to get the washer-die off without drawing all
the way through, though if you made the step slightly more gradual
then you probably could pass the whole tube through it.