That is what the threading dial and the documentation is for. Depending on
the gearing between the lead screw and the chuck and the threads you are
cutting you can engage the half nut any time, only when the the number 1 is
by the pointer, only when 1 and 3 are by the pointer ... the documentation
will spell it all out. What it is doing is synchronizing the chuck and the
lead screw so the cutter will always follow the same path with each pass.
When they removed the pipe from the chuck after threading all bets were off
as to synchronizing the existing threads with the cutter when they put it
back in the chuck. Easier to just start over again.
-----Original Message-----
From: Joe Szwed
Sent: Wednesday, October 19, 2011 1:00 PM
To: 'Arvid Jedlicka' ; shop-talk at autox.team.net
Subject: RE: [Shop-talk] Identifying taper and threading attachments on a
Arvid,
I think your right. When I did my apprenticeship back in the early 80's the
only cnc stuff I saw was used for high volume. In the shop I worked in, we
had two turret lathes for any volume parts and no cnc equipment. Two of the
Bridgeports had readouts on them. I think today's stuff is a lot easier to
program and used for a lot of small jobs too.
But for repair work and very small volume stuff, there are still some small
shops around doing it the old way.
Now having said that, I still on occasion deal with some small shops for
repair parts at work. The last part I hard made was just a short piece of
bar stock with both ends turned down and threaded for 1" pipe. The first
part they made, they didn't cut the threads deep enough. So I sent it back
thinking they would just pick the threads up and cut them deeper, but it was
faster and easier just to make a new part on their cnc lathe. And this was
a real small shop that operates out of an old chicken coupe.
Joe
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