General Purpose Tools

Rotabroach Cutter Kit


Precision hole making in sheet metal and frame materials

Rotobroach – a tool to replace a twist drill bit for “drilling” larger holes is thin metal. Often when cutting, say a 3/8″ hole in metal 1/8 thick, I end up with a hole that is kind of triangular. If I’m trying to insert a 3/8 rod in that hole I have to clean it up with a reamer to get it to work. I think the triangular hole is due to how the flutes of a drill bit “walk” around the hole as it is cutting.

I have tried different speeds but could never solve this problem until I tried a rotobroach. A rotobroach is like a plunging end mill with a spring loaded center punch to keep the tool centered. It cuts a perfectly round hole quickly and can be used with a drill press or a hand drill. A key to using this tool is to create a good divot with a center punch (included) to keep the tool aligned and try to keep the tool perpendicular to the surface so that all edges stay somewhat equally engaged in the material you are cutting. That said, it’s not tough to use with a hand drill. Another plus is you can cut large holes (1/2″ +) without needing pilot holes. This tool is made for body shops to cut spot welds out of car bodies, but it can be used for so much more.

I’ve used a rotobroach for about 4 years but I’ve cut triangular holes, cleaning them up with a reamer, for 10 year before that.

-- Randy Wells 12/28/17