Sharpening Forstner Bits
For forstner bits have serrated teeth on the cutting rim, clamp the bit in a vise and hone the back of each tooth with a triangular file.
Next, with the bit still clamped in a vise, hone the leading edge of the chippers with a fine hone, ensuring a flat plane and sharp cutting edge. Pay close attention to the intersection where the chipper meets the cutting rim. A crisp corner makes clean cuts.
Finish by using a triangular file to shape and sharpen the center spur. Be careful to not let the file touch the rim or any of the chippers.
Can You Sharpen Fostner Bits?
Yes. Sharpen the chippers by filing and stoning the throat face and lightly touching up the bevel. To file the throat face, use an auger bit file or a small hand file.
Sharpening Forstner Bit No-nos
Forstner bits are guided by the wide outside rim of the bit, unlike most drill bits, which are guided by the tip. Because of that, never sharpen the outside rim of the bit.
Forstner Bit Sharpening Kit
You probably already have all you need for sharpening forstner bits – flat file, triangular file and a doamond hone or stone.