Smithy Midas 1220 XL - Manual (Page 77)

15.4 Chamfer the end of the thread to
protect it from damage.
Cutting Left Hand Threads
Cut left-hand threads exactly as you cut right-hand threads, except this time feed the
carriage toward the tailstock instead of away from it. Reverse the cutter clearances and
grind the cutters back with a clearance angle on the left side. Swing the compound rest
to the left rather than to the right.
Cutting Multiple Threads
Cut multiple threads (Figure 15.5) one at a time exactly as you cut single threads, except
increase the lead to make room for succeeding threads ( a double lead for a double
thread, a triple lead for a triple thread, etc.). After completing the first thread, remove
the work from the centers without loosening the lathe dog. Then put it back in the lathe
with the tail of the lathe dog in the correct slot to index the work for the next thread. This
work requires a faceplate with accurately position slots, uniformly spaced and equal in
number to the number of threads to be cut.
Figure 15.5 When cutting multiple threads, increase the lead to make
room for succeeding threads.
Before
Tool
After
Single Thread Double Thread Triple Thread
15-4 Or Visit www.smithy.com
Cutting Screw Threads