An impressive if slightly scary tool for cutting clean, accurate, large diameter holes in sheet material or thin boards. Typical applications would be cutting holes for clock faces, ideally in a drill press, or in a hand held drill for drainage pipes, recessed lighting etc.
The central auger guides the tool into the work and allows the centre of the hole to be placed with considerable precision. The twin cutting spurs then incise the inner and outer edges of the main hole.
If it starts sounding like a propeller then you are going too fast. The exit side is pretty clean, but if a neat result is critical we recommend backing up the cut with a piece of sacrificial scrap material.
Cutting diameter 30-120mm, maximum cutting depth 50mm.