4-Facet Drill Bit Sharpening Jig

thingiverse

A four-facet point outperforms conventional point drills in cutting performance. Four-facet points do not wander, generate less heat, require less thrust, and last longer. Commercial four-facet sharpening machines like the Tormek grinder with DBS-22 attachment are expensive and difficult to use for precise hand sharpening of a four-facet point. This jig enables you to precisely and symmetrically sharpen all four facets without needing a grinder. Sharpening is done using 180-grit sandpaper on a flat surface. Choosing the relief angle: The primary relief angle should be determined based on the drill bit diameter and the material being drilled. Soft materials like mild steel, non-ferrous metals, and wood require higher angles than hard steel. Tormek recommends the following angles: * For 3-6 mm drill bits: 14° for soft materials, 11° for hard steel * For 6-12 mm drill bits: 11° for soft materials, 9° for hard steel * For 12-22 mm drill bits: 9° for soft materials, 7° for hard steel I have created three versions of the jig: * A 14° version for drill bits up to 6 mm, which can also be used for drill bits as small as 2 mm * An 11° version for drill bits up to 6 mm, which can be resized to 166% or 200% for larger drill bits * An 8° version for use where 7° or 9° is needed, suitable for drill bits up to 12 mm and can be resized for larger bits Usage: 1. Insert a drill bit into the jig. 2. Ensure the cutting lips are parallel to the guide lines. 3. Make sure the cutting lip is slightly higher than the jig's surface. 4. Gently tighten the screws, verify that the two halves of the jig are parallel. 5. Grind the secondary facets on sandpaper until you feel you're not grinding the bit anymore. 6. Grind the primary facets carefully and stop when all four facets meet at the center. Use a magnifier if needed. 7. Optionally lap the facets on 400-grit sandpaper for a mirror finish. Notes: * Feel free to donate, designing this jig was quite complex. * When drilling without a pilot hole, a split-point drill bit is faster than a four-faceted one. I'm working on designing a point-splitting jig.