Regrind a tap


Even taps become blunt according to the frequency of cutting threads. At the same time taps can be reground, otherwise the risk that the drill breaks. We have summarized below how you can regrind taps.

Even a tap becomes dull; then he breaks frequently

Cutting threads is a mechanical cutting action. Therefore, the cutting edge of a tap can become dull with time and depending on the intensity of use. The problem with this is that the tap is not uniform, so not linear dull. This often gives the impression that the tap is still sharp enough.

Due to the now different forces when cutting or threading, it often leads to the breakage of the tap. In many cases, a tap that was broken was no longer consistently sharp. So it does not always have to be the lack of cooling by cutting oil, which is why such a tap can break.

The grinding of a tap

First, the rake angle is reground. This can be seen in the plan view. The measure defined is the rake angle at the first full cutting tooth. The pitch of the grooves must be observed when grinding with the grinding wheel. Otherwise, it may happen that the tap now cuts too large.

Always pay attention to the right angle when regrinding

When grinding the groove in the spiral (the longitudinal groove), the grinding wheel must be adjusted exactly to the angle and swiveled in by one to two degrees. In a groove in the longitudinal view from bottom left to top right, the grinding wheel is to the left by one to two degrees higher than the actual peel angle.

Check the grinding wheel regularly

The grinding wheel must also be checked regularly during regrinding. If the profiling disappears slowly, renew it or use a new grinding wheel. After regrinding, the tap must still be cleaned and oiled.

Re-working the tap after regrinding

A wire brush is used for cleaning (pay attention to the matching alloy of the trim). It is cleaned from the tailoring of the tap to the cutting edge. Then the tap is cleaned with compressed air and lightly oiled with machine oil.

Tips & Tricks

Of course, we offer you numerous other guides and instructions for taps and taps. Here you will learn everything about thread cutting and drilling.


Video Board: DC Swiss - MEGA Tap Series - Regrinding