Carborundum File / Dressing Stick

This is an old-fashioned, simple, and inexpensive but very effective tool.
An aluminium oxide stone for smoothing sharp edges on glass and also ideal to be used as a dressing stick for diamond drills.

Dressing sticks made from silicon carbide or alumina oxide (soft bond) are usually used for dressing diamond tools. Sintered diamond drills must be used with the diamonds exposed properly through frequent dressing. Otherwise, the diamond matrix will glaze over.

The drill will begin to tear rather than grind which is very destructive. Tearing caused from unexposed diamonds creates friction. This causes uneven wear and heat cracks in the drill as well as the material being drilled, resulting in premature wear and will eventually destroy the drill. The more a diamond tool is dressed the cooler it will drill or cut.