A lathe turning tool in a drill rod is adjusted by a differential screw. When turning the red nut, it is advanced and the tool is retracted simultaneously. The resultant displacement of the tool is very small, (t2 – t1) mm in 1 rev. of the nut.
t2: pitch of the nut external thread.
t1: pitch of the nut internal thread.
The threads are right hand.
The tool is clamped by a setscrew after adjusting.