Sharpening drill bits

[ponytug]

I don't recall ever seeing anyone dip a bit in water to prevent burning, in a Drill Doctor demonstration, and don't understand why not. Will someone please enlighten me?

I was taught the "keep the blade cool" when I grew up, too. However, if the feed rate is low, there is no need, and the general idea turns out not to be true.

Longer story, with recent metallurgy analysis, it has been found that for many alloys (not all, especially for knives, not drills or chisels) localized heating of the metal, e.g. drill bits (and other cutting tools), doesn't affect the performance. As informal evidence, the number of folks who manage to sharpen their drill bits just fine on a grinding wheel, without using water.

I own a water cooled stone, which works great, but so does a grinding wheel and a 4 1/2" grinder for big blades. I personally have never found a metal edge that had a heat induced softness, but it is certainly possible that I missed it. I do like sharp knives; I think that they are both safer and easier to use.

All the best,

Peter

 

[repete]

Any folks from the Seattle area remember Boeing surplus in Kent? Bits by the pound.

 

[stuckmotor]

Because the sharpening wheel turns at a lower RPM so it don't heat un the bit like a bench grinder tends to do plus the collet that holds the drill while sharpening conducts the heat away from the tip of the drill bit.

Thank you! My only guess was that there might be a fan inside the device.

 

[bcp]

Any folks from the Seattle area remember Boeing surplus in Kent? Bits by the pound.

It was one of my favorite stores. Now Boeing sells their surplus in bulk by bid to businesses, I've heard.

Bruce

 

[Doofy]

Very timely thread. I received a Drill Doctor for Christmas about 10 years ago and forgot all about it. Time to unbox it and learn how to use it. I probably have a couple hundred bits to go thru. I really hate trying to use dull bits.

 

[bigtiller]

Because the sharpening wheel turns at a lower RPM so it don't heat un the bit like a bench grinder tends to do plus the collet that holds the drill while sharpening conducts the heat away from the tip of the drill bit.

agreed.
I just sharpened a 3/8 bit, changing the angle from 118 to 135. I squeezed the tip between my fingers and it was slightly warm, but a long way from hot.