Sharpening drill bits with the Eclipse 39
Pictured is the drill-sharpening jig I use. It is the Eclipse 39, a British-made device whose inventor won British Invention of the Year competition in 1970. The abrasive material is sandpaper taped to a flat surface. I use the plate glass top from a damaged set of bathroom scales.
The drill bit is accurately positioned in the jig and pushed over the sheet of abrasive. After a few passages across the surface the drill bit is repositioned and the other facet of the drill’s cutting surface is sharpened. The process is repeated until two good cutting edges are produced.
It is rather a long and demanding procedure, but has the advantage that a completely inexperienced amateur can transform a blunt drill bit into a useful item. I have seen seasoned metalworkers sharpen drills freehand on a bench grinder in just a few seconds and produce quality results. That is obviously a better way, especially for large bits, but requires skill which I suspect was hard won; there being plenty which can go wrong.
Sharpening a drill bit with the Eclipse 39 jig