Cutting special form internal threads – Smithy Midas 1220 XL User Manual
Page 83
Because the feed of successive cuts is toward, not away from, the operator, the
thread-cutting set is reversed. Also, you must take lighter cuts because of the cutter's
extension from the toolpost. Take an extra finishing cut without changing the setting of
the compound rest.
Cutting Special Form Internal Threads
You can cut internal forms in all the thread forms used for external threads. There is only
one factor that calls for special attention in cutting special-shaped internal threads: the
difference of clearances between the nut and screw recommended for different thread
types (Figure 16.8). If you don't have recommended clearances, it is safe to cut a nut
thread (internal thread) 0.005" to 0.010" per inch larger in the screws outside diameter.
Figure 16.8 Use different clearances between nut and screw for different thread types.
16-5
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