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Tapping machine hand tapping, thread diameter enlarged or reduced and causes of taper mainly has following several points:

1 hand tapping, reaming lever force imbalance, instability of the verticality of master, can not guarantee. The machine when tapping, tapping machine drilling machine spindle and tapping chuck vibration is too large, or silk hammer cutting and grinding was asymmetric, resulting in the threaded hole attack or attacks into "horn".

2 adjustable tapping machine die threading, tool diameter to adjust too big or too small, the diameter of thread cutting or cutting small. If the die swing badly, or cut into several thread, still exerted axial pressure, will also cut the small diameter of thread.

The 3 tap, die wear serious, threaded hole diameter processing is reduced along with the outer thread diameter is enlarged.

The new folding arm electric tapping machine and folding arm pneumatic threading machine can effectively avoid the disadvantages of common manual and tapping machine, screw precision attack out of 6H, not rotten teeth, not easily broken tap tapping machine