►I’d like to mention a few reference, you can reference manual the name of a specific individual parts and grinding method .
1. Shorter the horizontal edge repair, but you can’t repair gone. Because feed force will be reduced.(high speed steel taper  shank twist drill)
2. Use the opportunity to repair the short chisel, try to improve the negative rake angle chisel. Where increasing the rake angle can reduce the cutting force, so that brisk the drilling.
3. Using a larger variable-angle. Reduce friction, so that brisk drilling.(hss striaght twist drill)
4.Reducing the top angle. Usually hand drill feed has insufficient pressure, reduce the angle of the cutting edge appropriately can increase the cutting surface of the positive pressure, so is the belt drive. But too small can affect the rake angle of the cutting edge.
5. The lax requirement of aperture hole and roughness can be properly maintained two edge slightly unbalanced. Such apertures drilled slightly larger opening portion can reduce the hole edge with wall friction.

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