Sharpening an Auger Bit

I’m working on my Roubo bench today, and took a break to sharpen the auger git I’m using.

The first step (after finding my special auger file) was to coat all the edges to be sharpened with a black sharpie.  What is special about this file is that it’s very fine, and has “safe” edges, that is, edges without teeth.  The small size is important too.

Auger File

Here is what I do.  First sharpen the insides of the spurs.  Don’t file the outsides!  The sharpie makes it easy to see when you’ve got the nicks worked out, it doesn’t take much.

Sharpen the spurs

Then I file the back sides of the ramp, same deal, a couple of strokes with the file is all it takes.

Clean up the back side of the cutting edge

And finally, sharpen the top side of the cutting edge.

Sharpen the main cutting edge

These bits cut great when they are sharp.  I’m wondering if it would make a noticeable improvement to hit them with a fine ceramic stone to get more of a razor edge — I doubt it though.  I can drill 3″ deep with this bit in about 35 to 40 cranks.  It doesn’t take much time or effort.