Smithy Midas 1220 XL - Manual (Page 78)

What Not To Do When Cutting Threads
Do not disengage the half-nut lever. Do not shift the powerfeed speed lever. If you are
cutting between centers don’t remove the lathe dog until the tread is finished and
tested, and don’t disturb the spindle while the work is off the centers.
When you think the thread is finished and ready for testing, and only if absolutely
necessary, remove the work from the center, leaving the lathe dog attached. Then test
the thread. If it does not fit properly and you have to remove another chip or two, place
the workpiece back in the centers exactly where it had been. Then remove the hips and
test again. Repeat until are finished.
Finishing Off a Threaded End
After cutting a thread and before removing the threading tool, chamfer the end. This
improves its appearance and removes sharp corners and burrs. It also aids the screws as
it engages a nut or threaded hole.
Cutting Threads on a Taper
Cut threads on a taper the same as on a straight shaft, except in the setup of the tool.
Set the threading tool at 90 degree to the axis of the taper, rather at 90 degree to its
surface (Figure 15.6)
Figure 15.6 When cutting a thread on a taper,
set the threading tool at 90 degree to the axis of the taper.
15-5
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Midas 1220 XL Operator’s Manual