11V9 5″ Cup Wheel, CM-30 and CM-31

This is the original resin bond cup wheel for tool grinders. It is a bit bulky for today’s tools so we usually recommend one of the 11V9C Flared Cup Wheels. That wheel is flared, compared to the CMS-30 and 31, allowing for more complex operations such as end gash.

CBN versus Diamond

Choose CBN for high speed steel (HSS) tools and diamond for carbide tools.  CBN and diamond have similar hardness.  A key difference is that diamond grit media is composed of carbon which can interact chemically with the carbon in your steel tool when grinding at high speeds and temperatures.

Grit

The lower grits are recommended for most end mill end and flute grinding. If a finer finish is desired choose a higher grit

Diameter

We recommend the 4″ Flared Cup Wheel for basic tool grinders like the old CUTTERMASTERS (FCG-30, MG-30, CM-01) and our modern basic tool grinders (CM-01DC, JX). The smaller diameter gives better clearance in tight areas.

The 5″ cup wheel is recommended when position isn’t limited by the basic tool grinders. So if you are using the CM-Riser or have a tool grinder with height adjustment the 5″ Flared cup is preferable.