Sir, as I understand the #5 taper is 0,0526 inch per inch and the SB special taper has the size of about a #5 taper but the angle of a #3 taper, or 0,0502 inch per inch. The difference is 0,0024 inch or 0,06 mm. As you can enter a dial indicator with an arm easily about an inch or 25 mm into...