For each diameter, 3 taps are provided: roughing, intermediate and finishing. The user manual says to start with the blank, and then continue with the intermediate end up finisher. But ATTENTION, for my part and a first tapping experience (it was 10mm) on a test piece, when I spent the paver, the screws of the same diameter is passed completely through. By cons, when I use only the roughing and intermediate, there is perfect and the tapping screw is screwed normally. The same goes for a hole 8mm. So check this well on a test piece before tapping on the desired part.