Drill Bit Terror

V

Vincent Price

Joined
Feb 28, 2020
Messages
74
I'm as easy on drills as I can be. I have a fabulously beautiful $100 harbor freight table top press that is set to the lowest speed and i go slow and low with oil. But i still dont get much life out of my Ace Hardware carbide drill bits. I end up taking them to the point that I feel that they need re sharpened which I have tried on the 2x72 and not had any success. I have a box of bits that I have ruined the temper on. Has anyone ever tried heat treating them and then re tempering them just a bit like we would a blade to give them extra life?
 
No sir, but if the bits were sharp to start with, and they are truly carbide, and you're able to remove material (so you are presumably grinding with ceramic), you can sharpen them again, and possible even better than from the factory. When I was younger, I had the good fortune of being instructed in drill bit sharpening by a machinist. He showed me that if you know the right geometry for what you are trying to accomplish, a good eye and a little practice can have you getting your bits to perform like or better than new again and again until there is nothing left but a shaft. One important aspect of that is the relief edge. Your cut material has to be able to move out of the way easily. My guess is improved sharpening will resolve the issue better than attempting to re-heat and temper the bits. Just remove the part that you have overheated, and then get the geometry right. It can help to compare with a fresh bit. Also be sure not to hold the bit in the same place but keep it moving, and also hold it consistently at the same angle one hand, and only twist it with your other hand.

I hope all this makes sense, and I beg your pardon if you know a lot of this already. I will be subbed to see what other advice you receive, and accept any corrections my own advice may call for, though it has worked for me.
 
David Mary said:
be sure not to hold the bit in the same place but keep it moving, and also hold it consistently at the same angle one hand, and only twist it with your other hand.
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Okay, this needs to be worded better!

Hold the bit steady, resting your hand against the tool rest, with the bit not in contact with the abrasive, but say 1/8" or so away from it. Set your angle, and only when you are ready to make a pass, close the gap and touch the bit to the belt, and twist or rotate the bit in your hand so that the material is removed uniformly along the first cutting edge. Don't hold it against the belt, but make a pass and rotate the bit so the whole cutting edge is in contact with the belt for only, say, 1 or 2 seconds per 1/4" of cutting edge. That is what I meant by keep it moving. Then, without changing any angles, retract your bit 1/8" so it is no longer in contact with the belt. Rotate your bit over so the other cutting edge is ready to be ground, touch the belt again while rotating, and retract again. Dip the bit to cool it. Examine your progress and repeat as needed.
 
Let's see them. I"m sure they are not carbide. Unless you are using a carbine tipped masonry bit, they are referring to some pretty anti friction coating




Get a drill dr 750, read the directions, watch the videos, try it for yourself and yo can have really nice sharp bits.

Vincent Price said:
I have a box of bits that I have ruined the temper on. Has anyone ever tried heat treating them and then re tempering them just a bit like we would a blade to give them extra life?
Click to expand...

If they are carbide, or even if they are High Speed Steel HSS (most likely) the temper is not ruined.

HF drill bits are carbon steel, they are literally garbage and you could have overheated those.
 
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David Mary said:
Okay, this needs to be worded better!

Hold the bit steady, resting your hand against the tool rest, with the bit not in contact with the abrasive, but say 1/8" or so away from it. Set your angle, and only when you are ready to make a pass, close the gap and touch the bit to the belt, and twist or rotate the bit in your hand so that the material is removed uniformly along the first cutting edge. Don't hold it against the belt, but make a pass and rotate the bit so the whole cutting edge is in contact with the belt for only, say, 1 or 2 seconds per 1/4" of cutting edge. That is what I meant by keep it moving. Then, without changing any angles, retract your bit 1/8" so it is no longer in contact with the belt. Rotate your bit over so the other cutting edge is ready to be ground, touch the belt again while rotating, and retract again. Dip the bit to cool it. Examine your progress and repeat as needed.
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Hey thanks! Really dont know what I was thinking. Its not like I ruined the temper in the entire bit. I will certainly try and get more use out of them because it had definitely become an expense. I will re read and practice your suggestions.
 
They are marketed as Carbide but who knows for sure. I know they are not the Price of other carbide bits I have seen. These are average $10. I'll check into the Drill Dr.
12345678910 said:
Let's see them. I"m sure they are not carbide.


Get a drill dr 750, read the directions, watch the videos, try it for yourself and yo can have really nice sharp bits.
Click to expand...
 
I use the Norseman CN-TECH NITRIDE-CRYO M7 (not sponsered). I got them on eBay pretty cheap. I have probably drilled 250-300 holes with the .125 bit in .125-.25 thick annealed or normalized but not hardened tool steel and another couple hundred holes in non ferrous metal. It still cuts like new. I've been very impressed with how these bits preform on metals, they don't do well in wood or composite. I also think, as you are doing, center punching, lubricant and slow speed heavy pressue is important. As for sharpening. I've yet to have a reason to sharpen these. However I've sharpened cheap titanium nitride bits in the 2x72 with decent success. I watched an Ave and thisoldtony video on sharpening.

EDIT: just to add to the above. I used cheap drill bits for a while. Finally got mad when I couldn't get a hold drilled in annealed steel. Broke down and bought a good set and should have done it years ago. I don't regret it at all, money well spent.
 
Vincent, You say this is an Ace Hardware bit that's marked as carbide. Does this look like a regular metal drill bit? OR, is it a masonry spade bit? A properly sharpened masonry carbide spade bit will drill hardened steel nicely.

What type of material are you drilling? Is it hardened steel? OR, normal soft steel? 15N20 has a habit of being pretty hard when you get it. I've got some that measures around 40 or so Rc and is pretty hard to drill or cut with saw.

David has given some good advice on sharpening drill bits, either spade or twist.
 
Vincent Price said:
I'm as easy on drills as I can be. I have a fabulously beautiful $100 harbor freight table top press that is set to the lowest speed and i go slow and low with oil. But i still dont get much life out of my Ace Hardware carbide drill bits. I end up taking them to the point that I feel that they need re sharpened which I have tried on the 2x72 and not had any success. I have a box of bits that I have ruined the temper on. Has anyone ever tried heat treating them and then re tempering them just a bit like we would a blade to give them extra life?
Click to expand...
Ken H> said:
Vincent, You say this is an Ace Hardware bit that's marked as carbide. Does this look like a regular metal drill bit? OR, is it a masonry spade bit? A properly sharpened masonry carbide spade bit will drill hardened steel nicely.

What type of material are you drilling? Is it hardened steel? OR, normal soft steel? 15N20 has a habit of being pretty hard when you get it. I've got some that measures around 40 or so Rc and is pretty hard to drill or cut with saw.

David has given some good advice on sharpening drill bits, either spade or twist.
Click to expand...

But the odds are he won't have a diamond wheel to sharpen it with.
 
Ken H> said:
What type of material are you drilling? Is it hardened steel? 15N20 has a habit of being pretty hard when you get it.
Click to expand...

I'll add that it tends to air harden in thinner sections too, so if you are drilling holes in tangs after forging, even after normalizing, you will still have to anneal it before drilling. To anneal heat to ~1400 F, hold for a bit, then cool slowly to at least 1000 F, after which the rate of cooling doesn't matter. What I do is put the steel that needs annealing into my HT oven when I'm finished hardening my blades that are ready, turn off the kiln and leave them there until the next day.
 
12345678910 said:
But the odds are he won't have a diamond wheel to sharpen it with.
Click to expand...
A good 2X72 belt will sharpen a carbide spade bit nicely, but a diamond is certainly better. I've used 2X72 grinder to sharpen and reshape lathe carbide tipped bits in the past.
 
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12345678910 said:
But the odds are he won't have a diamond wheel to sharpen it with.
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First i used diamond plate to sharpen them.I even made special jig/holder for drill bits to keep right angle.Now i sharpen them free hand on that small diamond disk for Dremel .Just touch them from both side and they cut like laser..
 
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