Collection: Alpha Coupe

This collection brings together the Alpha Coupe reference distributed by Dagobert Industrie.

What is in this range

The set of 7 cobalt 5 % taps and 7 Gold&Black drill bits. See our hand tools.

Why cobalt in a tap

High speed steel with added cobalt keeps its hardness at a higher temperature than ordinary high speed steel. In a tap, whose cutting edge works in friction confined inside the hole and sheds heat poorly, that hot hardness translates directly into tool life, particularly in stainless and alloy steels.

Pilot hole diameter

This is the most common mistake, and it breaks the tap. The pilot hole is not drilled at the nominal diameter of the screw but at that diameter minus the pitch. For an M8 at 1.25 pitch, the pilot hole is 6.75 mm, so 6.8 mm in practice. Drilling too small loads the tap beyond what it can take; drilling too large gives a shallow thread that strips on tightening.