The Star Clutch Knob Screw: >>>>> It is 32 tpi LH the shaft mic's out to .1909 shaft length .5055" and the head is .5032" in diameter and .1560"in thick. This is off my 1940 Heavy 10. Danny >>>>> The Star knob screw on the 9N/10K, 10", 13", and 14-1/2 inch is 10-32 LH The 16" is 1/4-28 LH Ted >>>>> retaining screw on Star knob on apron(workshop/10K is 10-32 LF hand threads. >>>>>