Pipe threading on a lathe
Perhaps a known trick but as I (re)discovered it, I will pass it along
threading pipe on a lathe is complicated by the fact the thread is on a cone
with a 1 deg 47 minute taper, the options I read about were:
1) Don't. Use a pipe threader, that is what they are for.
2) offset tail stock and turn between centers
3) back the cross slide off a certain number of thou per revolution
well, my part is not a pipe and won't fit in the pipe threader
I could turn between off set centers but it is a fiddley setup to get a dog on
a short piece and then would have to set the taper up properly
and restore the tailstock to center when done
manually backing the cross slide off on the fly
when there are already plenty of things to keep track of
while threading a short section seems like inviting a problem
especially if there are a number to do.
the way I found was to use a jaw from the pipe threading tool
as a form tool just as you would single point an untapered thread of the same pitch.
Clamp the tool parallel with the face of the chuck
and back it off & disengage the feed (in that order)
when it just becomes fully engaged.
threading pipe on a lathe is complicated by the fact the thread is on a cone
with a 1 deg 47 minute taper, the options I read about were:
1) Don't. Use a pipe threader, that is what they are for.
2) offset tail stock and turn between centers
3) back the cross slide off a certain number of thou per revolution
well, my part is not a pipe and won't fit in the pipe threader
I could turn between off set centers but it is a fiddley setup to get a dog on
a short piece and then would have to set the taper up properly
and restore the tailstock to center when done
manually backing the cross slide off on the fly
when there are already plenty of things to keep track of
while threading a short section seems like inviting a problem
especially if there are a number to do.
the way I found was to use a jaw from the pipe threading tool
as a form tool just as you would single point an untapered thread of the same pitch.
Clamp the tool parallel with the face of the chuck
and back it off & disengage the feed (in that order)
when it just becomes fully engaged.