Drill 4.2 holes, tap 5 thread, choose what kind of drill sleeve
5 of the drill bit where to drill ah, with a drill clip on it!
Look at your drill sleeve material is what, if it is rotating drill sleeve, the direct selection of about 0.02 larger than the drill can, if they do need a kind of drilling quenching, will put a bit into the hole position accuracy -- mainly depends on your workpiece hole
Tapping 5 of the thread, drilling 4.2 of the hole, you need to drill sleeve, indicating that the screw hole distance, position tolerances, usually is + 0.1.In general, the tolerance of the drill hole to the choice of F7 is 4.2F7, that is, Phi 4.2 (+0.022 / +0.01).Drill sleeve material, you can choose T8, T10, etc., more than HRC60 quenching.Drill sleeve form can be chosen by oneself (fixed drilling sleeve, quick change drill sleeve, etc.).
