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Drill bits for high carbon steel


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I've tried about everything I can find locally and just can't get a drill bit that will cut through tangs and whatnot very efficiently or at all. I finally got a drill press which helped a lot, also found a cobalt bit near here and with the 2 I was finally able to drill a couple of holes for pins in some of the knives I'm working on and then it just stopped, can't get it to cut for crap anymore and I thought I was finally on a roll. I've heard carbide bits will do the trick but I can only find them for masonry. Any help would be greatly appreciated.

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Most of my tangs are dead soft since the blades have been clayed. Makes them nice and easy to drill that way.

You could always put the blade in water and soften the tang with a torch, but might not be doable depending on your goal.

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The one time I did get it to work the blades were still annealed and I got a couple of holes, but then nothing.

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What steel are you drilling?

 

What speed are you drilling at?

 

What lube are you using to cool the cuts?

 

Sounds like you were fast, too hot into too hard a steel, and the bit has become dull.

 

With a bench grinder you may be able to re-sharpen the bits.

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The one time I did get it to work the blades were still annealed and I got a couple of holes, but then nothing.
Are you careful not to overheat the drillbits? If they get too hot, they get tempered and lose their hardness. In that case I might be better off using cooling fluid while drilling. That said, I've had similar problems with common drillbits from DYI stores as well when drilling bronze. They just wouldn't grab the metal. It's more due to the geometry of the tip I gather (too small angle of the V perhaps?). I got some other drillbits which don't have the standard V tips, and they drill much better.
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Are you using a drill Press? I have used off the shelf High Speed Steel bits to drill steels like D2 and all manor of stainless steel including ATS34 so you shouldn't be having any problems with Carbon Steel.

 

I have no idea where your coming from so I will backtrack a little with fundamentals.

 

Be sure you have a good place to start.

 

Mark your spot with ink.

 

Take a Punch and strike it.

 

There should be a clean indention from the strike, this will hold the bit in place as you begin to drill your hole.

 

Keep your bit cool, before I used WD40 but water works great and its easier to clean up.

 

A simple water bottle with a small hole in the lid is good enough, at least its worked great for me.

 

 

Tangs should never be hard, not in my experience anyway. The softer the tang the less likely it is to crack or shatter during hard use. If your tangs are hard you may want to look into your heat treat and tempering.

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Going back and reading your original post, you may want to find yourself a good drill bit sharpener. There are a few real good ones I have seen lately come onto the market.

 

If your chipping off the tips of your edge and breaking bits your probably trying to drill to fast. If they are dulling up then you may need to work harder to keep the bit cool.

 

You may want to go over and hang out at somebodies shop and see if your missing a step in the process as its pretty hard to guess about without watching you work.

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I asked a similar question years ago, and was informed I needed to learn to sharpen drill bits... :rolleyes: For 1/8th inch and up, its not that difficult, anything smaller it tough to get right. Also, it sounds like your steel is still somewhat hard. If a standard anneal doesn't do the job, try a sub-critical anneal. Basically you heat it up to just under critical, hold for a minute, then let it cool. It amounts to a very high tempering cycle, and is really good for L6, o1, and other deep-hardening steels that tend to air harden in thin sections.

 

Something else that works for me when you get the hole started then it stops cutting. Make a small punch with a 4-sided point, and punch inside the hole with it. for some reason, it helps the bit grab better, enough to finish the hole...

 

O1 may be the worst steel to drill that I've experienced, 5160 and L6 are not much better. If you're going to be using these steels on a regular basis, carbide bits might be a good investment. Go slow and light, and use lots of cutting fluid.

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Thanks GEzell, I think that pretty much answered it, I've got the steps to drilling holes down years ago in machining class, but I think the main problem was the cutting speed and the lack of cooling fluid. I had just gotten the drill press and was excited about it and started playing with it on the setting it came in, which was the middle setting, but I had already worn out the bit before I realized to change it to the slowest setting. Plus I only dipped the bit in oil once before starting. The steels I was drilling at the time were o1 and 1095. I got another of the cobalt bits to try angain yesterday but this time I'm just going to take it slower and easier and see where that gets me. If that still goes dull too fast I'm just going to have to order some carbide ones, I just hate ordering things. Thanks for the advise fellas!

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I have used this afternoon a carbide drill bit to enlarge a hole in the tang of a hardened stainless steel kitchen knife. They work very well for about everything!

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