How to Sharpen Forstner Bits
- 1). Clamp the Forstner bit into the vise with the top of the bit sticking up about 2 inches.
- 2). Insert the file into the recess of the bit, in between the rim perimeter and the center cutting edge. Get down at eye level and look across the top of the bit as you hold the file.
- 3). Tip the file back and forth. Watch as the file rocks over the sharp cutting edge of the rim. When the file matches exactly the slope of the cutting bevel, stop rocking the file and hold the file steady. Maintain this angle as you file up and down in short strokes, watching where your file is marking the rim's edge. Focus on holding the file flat against the bevel as you work your way around the semi-circle, filing up and down.
- 4). Pull out the file. Examine the edge; it should be shiny and clean and should feel sharp to the touch. Insert the file into the recess on the other side of the bit and start filing up and down on that side. Keep checking to make sure your angle matches the pre-existing angle and file around the perimeter of the semi-circle knife until it is shiny, clean and sharp.
- 5). Lay the file on the chipper bevel, the thin, angled lip near the bit's rim. Rock the file gently until the file is at the same angle as the bevel. Begin filing back and forth, sharpening the bevel. Stop occasionally to get at eye level to make sure your file matches the bevel's angle. Work your way across the bevel. When it is sharp, move to the other chipper bevel and sharpen it the same way, always making sure to maintain the angle.
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