Drill Bits

[Frontal]

Probably about 35 years ago, an old guy that I knew showed me how to drill properly, and how to sharpen bits on a bench grinder.

The lesson that he gave me has served me well my whole life, and infact the current set of bits I have is about fifteen years old.

A great trick that he showed me was, when drilling steel was to take a small square (2") of cotton material, fold it up on itself a few times, soak it in water and drill through that directly onto the steel at a nice slow speed.

The cotton wad keeps the heat down with the water, and absorbs a lot of the vibrations.

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[Frontal]

Yeah, I have a very skilled machinist/weldor friend that sharpens bits by hand. You (and he) are a badass!

Probably a skill I should learn frankly. Just always seem to be in a hurry to finish a project when the inevitable broken or dull bit comes up and then it's one of those afterthoughts where I should have invested that time to learn up front.

It's a simple skill to learn, all you need is a bench grinder with a good rest on it with a fine grain size.

The trick is to use plenty of water when sharpening, dip the bit in a cup of water every few turns to keep it nice and cool.

1) Hold the drill bit so that the cutting face is parallel to the grinding wheel surface. The idea here is to remove only as much metal as needed to clean up the cutting edge.

2) Slowly bring the bit into contact with the wheel. Keep the bit as straight as possible, without rotating it. We aren’t trying to duplicate the original curvature of the factory grind. Instead, we’re making a new, flatter cutting face.

3) The heel portion of the cutting face should be ground slightly more than the edge. This will cause the cutting edge contact the drilled surface first, when in use.

4) When you sharpen drill bits, metal is removed and the steel will begin to heat up. Dip the bit into water frequently to keep it cool. If it gets too hot to hold in your bare hand, you’re either grinding too fast or not dipping and cooling often enough.

5) As soon as the cutting edge is sharp, spin the bit half a turn, and begin sharpening the other cutting face. The more evenly you can grind the two edges, the better the bit will perform.

6) When you’ve got both edges sharp, check to see if they are the same width. Look at the drill end-on. The two cutting edges should almost meet to form a point in the center of the bit diameter. There will be a short line centered between the two. If not, no problem; just grind a little more on the wider side until the two even up.


Are both edges sharp, the same width, and centered?

Good!

 

[Blues]

I've tried cobalt and titanium bits. I'm back to using steel bits, tap magic and a Drill Doctor. Proper lube makes a big difference, especially on thicker material.

 

[cosmokenney]

Any of you machinist-types have a good set of drill bits you recommend that won't cost a fortune. I'm not opposed to spending a decent amount. I'm tired of throwing out HF bits after 1 or 2 uses.

Might want to invest in a drill bit sharpener. And run your drill as slow as possible to keep from cooking the bits.
I still have trouble getting the speed and pressure correct when using a hand drill and cook a lot of bits too. But on my drill press set to 460 rpm I can drill dozens of holes without much effect on my bits. Use lots of cutting oil on the work piece and on the bit itself. The oil is really meant to take heat out as much as lubrication.

 

[fat_head]

This review just popped up on youtube. Very relevant.

tl;dw Bosch and Dewalt performed the best in $40.00 or less drill bit sets. However even the Bosch failed spectacularly when intentionally misused.

 

[word302]

This review just popped up on youtube. Very relevant.

tl;dw Bosch and Dewalt performed the best in $40.00 or less drill bit sets. However even the Bosch failed spectacularly when intentionally misused.

The reality is none of the "name brands" really hold up that well long term. The Bosch bits he tested were the only cobalt in the group, so not really a fair fight anyway.

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