Can you sharpen wood auger bits? I have a few in the 3/4"-1" sizes that have almost stopped cutting and don't want to throw them away if I can get more life out of them. Thanks.
Yes they can be sharpened. Get the right file width and try to avoid removing any of the outside cutting lip that cuts the wood fibers before the flat chisels the chip out. If no metal has been hit with the bit, they are quite easy to sharpen. There should be some books in the library that will tell you how to sharpen them. Old wood machining books probably are the best, but old carpentry books should have the information too.
In the days wood auger bits were used for the majority of hole boring in wood, it wasn't a "throw-away" society, and you can bet the bits were sharpened a lot, and treated with a great deal of respect, as one could not afford to buy another very easily.
An augur bit file (see picture) makes this easier to avoid the problems beenthere mentions. It is tapered to fit into different size bits, cuts on the flats on one end and on the edges on the other, but a flat file of the right width also works.
To sharpen the cutting lips, I just use a flat mill file, with a kind of rounded stroke to follow its contour, making sure the unmilled edge is down.
I have ground the screw completly from the end of a couple of my long augers and filed the cutting edge a little more aggressive so it will pretty much self feed. They work great in big timbers if your not to pickey where they start. A pilot hole can also be used if you need to hold the centers.
My favorite drilling setup, for 1/4" holes and up, was a 1/2" VSR drill with auger bits, because they drill straight so well and clear the hole of chips.. The 1/2" drill was necessary for some of the larger sizes. You sometimes could find augers with hex shank ends, or just cut off the end meant to go into a bit brace.
Augers are a most useful drilling tool, including the modification you mention. Years ago, I used to grind off the screw for using them in a drill press, until I discovered Forstner bits.
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