Drill Bits

Big Smitty

Big Smitty

Joined
Aug 30, 2007
Messages
509
I am in need of some info on drill bits for drilling pin holes. I use 1/4" pins on my knives and right now am using mostly 1/8" O1 PGFS. My issue is that the drill bits are grooving on the side of the bit about 1/2 way through the hole and ruining the bit. I have been using titanium and black oxide drill bits. Is there another type of bit I should use. I have a drill press and just need general direction on drilling O1, I must be doing something wrong.
 
PGFS comes spheroid annealed. O1 drills pretty well. Unless you're using a really cheap bit, this should be a workable problem.

O1 will work harden, so make sure you're using enough force to keep it feeding.

A lubricant or coolant will prevent the bit from getting too hot. Remember not to spray coolant on a hot bit, keep it wet.

I often start the hole, pull the bit out to let coolant into the hole, and finish the hole. Let off the feed pressure once the bit starts to exit the back side so your feed rate stays even.

Titanium nitride coated stuff has never done much for me except in aluminum. The black oxide imparts some lubricity and rust resistance, but again, it isn't doing much. Most any old HSS bit should be up to this task.

Your RPM should be around 600-700, your feed rate should be around 3 inches per minute. Slow down if you get much chatter.

There should be no need to predrill a 1/4" hole with a smaller bit.
 
bartblade said:
is the steel annealed
Click to expand...
yes it is annealed

Nathan - Thanks for the detail, I will look for a HSS bit. I also think I may need to slow down my drill press a bit. It may just be the fact that I am running to high a RPM and smoking the bits. Sometimes I can't see the forest for the trees. I know O1 shouldn't be to hard to drill, but I am smoking brand new bits in the current set up. I'll figure it out.
 
Nathan the Machinist said:
Most any old HSS bit should be up to this task.
Click to expand...

Nathan - I'm glad someone agrees with me on this one! I prefer to use plain old M2 drill bits, black or gray ones. I'll use ti-nitride if I get them nice and cheap.

I also think you need to watch speed and lubricant, keeping it cool will probably help. Also, chunk the bits (or sharpen them if you prefer) whenever they start cutting poorly.
 
AcridSaint said:
Nathan - I'm glad someone agrees with me on this one! I prefer to use plain old M2 drill bits, black or gray ones. I'll use ti-nitride if I get them nice and cheap.

I also think you need to watch speed and lubricant, keeping it cool will probably help. Also, chunk the bits (or sharpen them if you prefer) whenever they start cutting poorly.
Click to expand...

Thanks Acrid - I slowed down the drill press and tried some lube and things are working better.
 
Nathan the Machinist said:
PGFS comes spheroid annealed. O1 drills pretty well. Unless you're using a really cheap bit, this should be a workable problem.

O1 will work harden, so make sure you're using enough force to keep it feeding.

A lubricant or coolant will prevent the bit from getting too hot. Remember not to spray coolant on a hot bit, keep it wet.

I often start the hole, pull the bit out to let coolant into the hole, and finish the hole. Let off the feed pressure once the bit starts to exit the back side so your feed rate stays even.

Titanium nitride coated stuff has never done much for me except in aluminum. The black oxide imparts some lubricity and rust resistance, but again, it isn't doing much. Most any old HSS bit should be up to this task.

Your RPM should be around 600-700, your feed rate should be around 3 inches per minute. Slow down if you get much chatter.

There should be no need to predrill a 1/4" hole with a smaller bit.
Click to expand...

Would these recommendations stand for annealed 1095 as well? I've a nice old Rockwell Delta bench press in the garage, and some holes to drill. :)

How hard is annealed 1095, roughly? I was thinking of making a general abuse prybar out of a piece.
 
I am just getting into this, so not sure about O-1. Keeps posted please as that is what I am learning to grind on.

On drill bits. I used to work as a mechanic, and what I found to cut best through hardened automotive engine type stuff was carbide bits. Back in the day they were about $25-$30 for ONE 1/8" bit, so they are pricy, but do work on that application. Not sure if this helps.
 
I'm a newbie, and could not drill 5160 with my hand drill to save my life. Even using cobalt bits and cutting fluid made no difference.

I recently got a drill press, and now 5160 and O1 are a breeze for me to drill even with old bits and no cutting fluid, so I think the slow speed should solve any problems you might be having.
 
michdad said:
I am just getting into this, so not sure about O-1. Keeps posted please as that is what I am learning to grind on.

On drill bits. I used to work as a mechanic, and what I found to cut best through hardened automotive engine type stuff was carbide bits. Back in the day they were about $25-$30 for ONE 1/8" bit, so they are pricy, but do work on that application. Not sure if this helps.
Click to expand...

Carbide bits? Do you mean the carbide tips as is used for drilling masonry, or vanadium carbide?
 
I think he means solid carbide bits. They don't work well if there's any flex or play from side to side, they are so hard that you can snap them easily. This is the way to go if you're drilling hardened steel though.
 
Sword and Shield. You should be able to drill thru annealed W1,1095, 5160, D2, and just about any other steel, with a good sharp bit, a drill press and some oil. Annealed they should all be way softer than a drill bit. I think Nathan was the one that stated a while back that the tool only has to be a few points harder than work to cut it. I have spot annealed simple steels and drilled them. Just get the area a deep blue and cool slowly and it should drill. I have even done that with a 52100 ball bearing.
 
Cold rolled steel can be tough.
Stainless is a real pita to drill.
Nitrided bits are good for some materials, but the coating gives the bit some wear resistance, but not the hardness and, most of all, high temp hardness needed to drill some steels.
Drilling many SS steels keep in mind that, if you heat them too much, they'll harden and become un-drillable! :eek:

Personally, the few cents saved on a nitrided bit over a cobalt bit aren't worth the trouble.
I use only cobalt bits, and always could drill annealed K720, C70, 5160 and similar carbon steels without a glitch.
Work hardened or tempered steel can't be drilled with HSS, nitrided or cobalt bits, period.
You either have to anneal it, or use Widia bits, which can be as expensive as a complete set of cobalt bits, so I try to avoid to forget drilling my holes before heat treating. :D
Done it once, the blade is still there, as a memento of my lapse in stupidity. :p
 
AcridSaint said:
I think he means solid carbide bits. They don't work well if there's any flex or play from side to side, they are so hard that you can snap them easily. This is the way to go if you're drilling hardened steel though.
Click to expand...

Yep, solid carbide is what I was using. They would cut anything I was using them on, but yep, they break VERY easily!
 
ib2v4u said:
I think Nathan was the one that stated a while back that the tool only has to be a few points harder than work to cut it. .
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Jim,

If I said that, I misspoke. I don't think a HRC 66 bit is going to cut HRC 62 steel (a few points softer), though it might cut 50 HRC steel (and will certainly cut spheroid annealed). The harder material will scratch the softer material, but as you know, there is more to drilling than just a scratching mechanism.

I think I know what thread you're talking about and went back and read it. What I said was (in the context of a drill cutting hardened steel)

Nathan the Machinist said:
In order to cut, the web has to penetrate the material. If the material you're cutting is hard, it takes a lot of pressure on the web of the bit to feed it in, otherwise it will just rub. If it is going to cut, you're going to have to lean on the bit hard. If the bit is HRC 65, and the steel is HRC 55, this might work. But that probably isn't the case...
Click to expand...

I wasn't very clear about what I said. In the context of what you're saying you're exactly correct, I did kind of say that. But that isn't what I meant, and it is wrong. Sorry for the confusion.

Nathan
 
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I've personally found that sharp, new M2 bits outcut cobalt. I don't know where I can get cobalt bits nearly as cheap as I buy plain black/gray M2 bits or ti-nitride. My secret is to throw the bit away when it doesn't cut. I was told once that anything under 1/4" can't be re-sharpened accurately anyhow and I rarely use bits larger than 1/4"
 
Drill your holes before grinding the tang taper as that may cause some work hardening.

If the bit doesn't get hot, it should not have any trouble with annealed steel. I regularly drill D2 and S30V without any trouble.
 
What kind of bit/method should I use to drill stainless? I have a press on the slowest speed (700 I think, on mine), and used cool tool, but still kept wearing out bits (like 1 and a half holes was the best I got with a bit that said it was meant for metal. Should I buy a carbide bit?
 
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