B25T Servo Spline Rotary Broach Punch Tools Cutter 0.5 inch Shank 12.7mm

All punch bit is positive tolerance +0.05mm, like 6mm, you get the bit is 6.05mm. Like B25T, you should use drill bit to do a hole 4.2mm. 2, Use punch bit B25T to working in the hole, at first, cutting feed slowly, like 300-500 is ok.