Can I ruin the temper on my auger bits?

[Jessica Pierce-LaRose]

Drilling a bunch of holes the other day to clear out a large mortise, using my vintage Irwin auger bits, I managed to heat up my auger bit enough that it was darn hot. I don't really know that much about tool steels, nor how these are tempered - differently than my plane blades, I would assume, since you can sharpen these with a file. But do think I can actually get these hot enough to ruin the temper? How would I know if I got them too hot? Would I see some color change, like when you overheat a tool on a grinder, or is it more subtle than this?

Sorry for the sort of dumb question - a precursory search hasn't turned up much, but I also don't really know what search terms to use to find more specific information . . .

[Eric Brown]

IF the bit is sharp, it will still get pretty hot when boring hard woods, deep holes, or many holes. Typically it won't get hot enough to lose it's temper. The caution might be about how hard you are working. IF the bit is dull and you are working real hard, its possible to bend the bit. I've even seen some of lesser quality bits even "untwist".

Depending on the situation, a different type might perform better. The Russell Jennings type is one good choice.

Check the sharpness and let the bit cool off between holes if you are still concerned.

Good luck. Eric

[Jessica Pierce-LaRose]

Yeah - I've bent a bit in the distant past - I thought I could put just a bit of english on it and get it to bore a little more in one direction - once that lead screw is engaged, it really only goes one way, though. Stupid on my part. It didn't think I was forcing it at all, but turns out I was. My bits aren't in the greatest condition; I'm not convinced someone didn't hone the outside at some point on a couple of them - they certainly sharpened the wrong sides of the cutting edge. At least one of my bits is cutting more on one lip than the other, and I haven't taken steps to remedy that, but I think the bit I was using was all right.

These were fairly deep holes in hard maple, and large diameter as well.

I've been meaning to pick up some nicer bits, but nothing has come my way. There's some Jennings for sale at Sydnas Sloot I've been eying, but I've been saving my pennies for the Lie Nielsen event in Montreal next month. With the workbench mostly behind me, I'm hoping my days of drilling these very large holes are done for a while.

[Mike Henderson]

If you're using a brace, all of that heat energy is coming from your muscles turning the brace. It'd be pretty difficult to generate enough heat to soften the steel, given the mass of the bit and the way the wood (and the moisture in the wood) absorbs some of the heat. Not impossible but pretty difficult.

Mike