Sharpening Auger Bits

[Lurcherman]

Hi folks,

I was just up in New England for a long weekend, and picked up some tools at a shop that is still called a "used furniture" store, instead of the higher priced alternative word "Antique".

I bought a couple of chisels, a 2" ship auger, and the real prize: a boring machine. There is no depth stop, but it does have an adjustable angle head and pivoting rack for bit extraction. It came with a 1-1/2" auger bit already installed.

Although they are in pretty good shape, as might be imagined these auger bits could use some sharpening.

Any suggestions for sharpening augers?

[beenthere]

Here is a pictorial for sharpening auger bits. Important to only file inside, not on the outside that might reduce the diameter of cutting circle.

http://www.fine-tools.com/G-augerbitfile.html

[Brad_bb]

Sharpening the cutting edge is just like sharpening a chisel.  I use sand paper wrapped on small pieces of wood.  Starting on the coarsest needed to fix chips or deep grinding marks, then work my way to finest grit.  I might use 80, 150, 220, 320, 600, 800, 1000.  I probably wouldn't use every one of those, but most.  Maybe skip the either the 600 or 800.    After the coarsest grit, it goes quite fast.  If you can't get it pretty sharp within 5 minutes, something is wrong.  Remember that usually new bits are not properly sharp and won't cut properly.  I had to buy a new Irwin bit to install a lock in a door.  I think it was 3/4 or 7/8 bit, but anyway it was not properly sharp out of the package.  It had coarse factory grind marks, a burr etc.  I had to work all those marks out to a polished surface on the face cutting edge and also did some work on the spur, the inside, not the outside (okay maybe a did a light polish on the outside, but not enough to change dimension.

[Lurcherman]

Thanks guys - these bits I have are nowhere near being new. I'd be surprised if the newest of the two I just got is less than 40 years old.

[Dave Shepard]

On my auger bits I use a fine small file, sometimes a three cornered one. The steel is too soft for much more than that. I've seen so many auger bits ruined by being sharpened on the outside. An honest mistake, but a shame none the less.


Dave

[moonhill]

If the bit is really rusty you need to clean up the outside to get rid of the pits but no more.  I'm guessing the bits you picked up are flat bottomed, no spurs hanging down?  If so a flat file cleans them up quickly and can be polished Brad's way. Yup, triangular files are a plus.  Keep your angle correct, you want your leading cutting edge to be just that leading and cutting, not riding on the flat of the bit.  I like my bits sharp enough so when you clean the excess chips off the bit after a hole you can cut your fingers with no effort.  Boring holes can be a bloody sport, it's about the only exciting part.   Tim B.