05-05-2017, 05:48 AM
1. Engage the half nuts to take the first pass.
2. Turn the motor off and at the same time, advance the cross slide to move the tool out of the thread (this prevents turning a concentric ring that will induce a stress point. If you can turn a groove for the tool to enter, or the piece is threaded all the way through it makes it easier, as you know the tool has cleared the thread. Otherwise, set a stop or mark the tool and you can always stop a fraction early and then turn the chuck by hand.
3. Advance the cross slide so that the tool completely clears the thread (I usually go one revolution on the dial, so I don't get confused).
4. Put the lathe into reverse and back the tool out until you are clear, and stop the lathe.
5. Set your next depth of cut, put the lathe back into forward and turn the lathe back on.
6. Repeat steps 2 through 6 until your thread is complete.
I do a spring pass every third pass because internal tools will flex a little. You simply take another pass without advancing the tool (i.e. take the same pass as the last cut).
Of course, if your chuck isn't a screw on one, you could turn the tool upside down and cut the thread on the back of the piece. To do this, you place the lathe in reverse to take the cut, as the carriage will then run toward the tailstock. No risk of crashing the tool into the chuck. Same process as described above but the directions are reverse.
Hope this helps and that I haven't missed something but that is how I do it.
2. Turn the motor off and at the same time, advance the cross slide to move the tool out of the thread (this prevents turning a concentric ring that will induce a stress point. If you can turn a groove for the tool to enter, or the piece is threaded all the way through it makes it easier, as you know the tool has cleared the thread. Otherwise, set a stop or mark the tool and you can always stop a fraction early and then turn the chuck by hand.
3. Advance the cross slide so that the tool completely clears the thread (I usually go one revolution on the dial, so I don't get confused).
4. Put the lathe into reverse and back the tool out until you are clear, and stop the lathe.
5. Set your next depth of cut, put the lathe back into forward and turn the lathe back on.
6. Repeat steps 2 through 6 until your thread is complete.
I do a spring pass every third pass because internal tools will flex a little. You simply take another pass without advancing the tool (i.e. take the same pass as the last cut).
Of course, if your chuck isn't a screw on one, you could turn the tool upside down and cut the thread on the back of the piece. To do this, you place the lathe in reverse to take the cut, as the carriage will then run toward the tailstock. No risk of crashing the tool into the chuck. Same process as described above but the directions are reverse.
Hope this helps and that I haven't missed something but that is how I do it.
Hunting American dentists since 2015.