Drill bits

J

JoshEarl

Joined
Sep 30, 2007
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197
I haven't done much metal drilling, and I'm trying to figure out what I'm doing wrong here.

I'm working on making a few blades from a bar of 1095 that's 1/8" thick. I'm trying to use my drill press to reduce the amount of hacksaw work I need to do.

After realizing that my old set of bits wasn't up to the task of drilling steel, I got a set of Dewalt gold-colored bits from Home Depot. They cost about $25.

The 1/16" bit cuts through the steel pretty easily. But when I stepped up to a 1/8" bit, after a few holes the drill started making little chips instead of shavings. I'm using a machine oil right now until I can get a proper cutting oil. The drill is making crackling noises when I apply pressure.

These appear to be the best bits I can buy at Home Depot. Are they really that bad that they can't handle annealed steel? (I got my steel at Texas Knife, which claims its stock is annealed.) I realize good bits can be expensive, but I would think that cheaper ones would last more than 10 holes.

Thanks for the help,
Josh
 
You didnt say what speed you are running the drill at....for steel you will want to run it as slow as possible usually.
 
Get some bits from Enco. They are cheap and work. You might want to slow the drill press down a bit and use cutting oil. You might also try "pecking" at the hole: apply pressure, back off, repeat as necessary. The crackling sound indicates that the bit is close to giving up the ghost.

Gene
 
I don't use anything less than Cobalt Drills after much frustration. Then there is Carbide, but easy to break if you're not careful.
 
"gold colored bits" have a coating of titanium nitride which is wear resistant. I tried some gold colored ones ,just once ,when I found it was all for show as the bits weren't ground properly so the TiN was worthless. Stick to good quality cobalt or carbide bits !!!
 
Are you using the 1/16" bit as a pilot for the 1/8"? If so DON'T! Just centerpunch and drill your 1/8" hole. Even Home Depot bits will cut through your 1095 w/out problem if you run the proper size for the hole you want and run slow and use cutting oil.
Matt
 
Is that factory spherodized annealed 1095? or home annealed?
First, as has already been said, run slow and well oiled, also helps if you start in a centerpunch divot, it helps the bit get a bite before it builds up heat. I drill annealed tool steel at around 200RPM with normal Sears bits. That said, I recall something Kevin Cashen said in a lecture about 1095 carbide platelet formation (carbides precipitating out into flat plates if the anneal isn't perfect) that will "squeak a drillbit" meaning that you might as well be trying to drill a chunk of carbide as far as how a drill bit sees it. I do not remember the remedy for that little nuisance.

-Page
 
You should be able to drill the hole out with you 1/8th without using the 1/16, MDOYLE is right about this. Also slow the drill press down to its second lowest speed for small holes like these, do not run at high speed. Go light on the pressure, do not push.

If the bit goes dull, STOP! Remove bit and go to your belt sander and sharpen the bit using a 220 grit. This is easy, look at the angle of the bit, line it up to the grinder and touch it up- takes 2 seconds and you are back in business with the drilling again.
 
Thanks for the replies, everyone.

The steel is factory annealed; I'm still working on the forge thing, so I don't have a way to anneal it myself yet.

I was using the 1/16" bit as a pilot for the 1/8", so I'll avoid doing that again.

I checked again, and the bits are marked as titanium split point.

The slowest speed on my drill press is 570 rpm, and I'm getting the sinking feeling that that might be too fast.

Josh
 
I find that just plain old black oxide M2 bits work fine. But, I use cheapo bits almost exclusively, so I also use Ti nitride. The M2 bits cut better, especially in larger sizes. If you haven't slowed your drill down yet, I would suggest doing so.
 
MSC-Direct
or Enco are good suppliers. MSC is related to Enco...sometimes you order from Enco, you might receive product with MSC lable on the package.....
They also have pretty good sales occasionally....when to stock up.
Cobalt is slightly more cost than HSS and worth the difference.
Carbide while much harder is much more costly....I only spend that for carbide if I am drilling already heat treated steel....and breaking a $10.00 or so carbide bit rapidly eats into profit if you are making to sell.
Also rather than cutting oil, I like a crayon shaped stick called Tap-Ease...MSC has it and I think Enco also does.....just a personal choice......
 
For sharpening drill bits I spent around $100 on a "drill Doctor" drillbit sharpener, little gadget paid for itself in a couple months, and I've found it actually gets the bits sharper than they come from the factory. Not only is it great that I no longer have to replace bits when they get dull or try to hand sharpen them (big PItA and not accurate enough for my tastes) but the problem of trying to find that replacement 13/64th bit at 11:35 Saturday night is no longer presenting itself (because of course that is when you will be trying to tap a 6x1 metric hole and find your bit no longer cuts)

-Page
 
i have tons of the cheap gold bits you speak of. and your description of the sounds and how it acted are very familiar. when the bit stops cutting and doing the routine you described is when i sharpen the bit im using. i usually am drilling home annealed 5160, and it is still too hard to drill sometimes. when im having a real hard time drilling i change the angle to a (slightly) sharper point. the small change usually makes a big difference so it can bite in and start cutting again. and as a rule when drilling with a pilot hole, its best not to re drill a hole where less than half the cutting edge is in material, its a good way to break off corners on the bit. slow speed is good, but my HF bench drill press is too fast and still does fine. good luck to you.
-Lou
 
If you are buying bits from industrial suppliers like Enco or MSC, buy the sizes you use commonly in whatever packs they sell them in. Even if you are able to sharpen them, they can break such that they are too short to sharpen. It is probably cheaper overall too.

Note that if you have a Grainger store handy and you (or someone you know) work for a company that has an account there, you can get some kind of "corporate discount" or "wholesale price". Just give the company name (account number not required) and pay with cash or your own credit card when you pick up the item. My total cost, with tax is typically less than the catalogue price.

Phil
 
Your problem goes back to what Kevin Cashen said about the carbide platelets. All of the 1095 I used to get from Admiral was CRA, but it is not spheroidized annealed, and is hard on bits. Use cobalt, or, and, spheroidize anneal it. I found improvement by re-annealing it, but it was still a tad hard on bits. Better, but not ideal.
 
I am in the process of making some 1084 stock removal knives from stock I have only used for damascus in the past. I'd never cut it with a bandsaw before, only the chop saw. When I went to sawing out the blanks, I hit soft spots and then spots so hard it would barely cut and actually dulled my blade some. Prior to drilling holes, I decided to take it through a full anneal in the furnace. Hardness now is about 20-25 HRC, and it drilled very nicely. :) The downside, of course, is now I have to thermal cycle extra to get it in proper condition for final hardening.

I use mostly screw-machine length HSS bits and buy them from MSC on sale by the dozen in 1/8 and 3/32". When they dull, I toss or use them to make scribers, gravers, try-fit pins, etc. For larger bits, I agree with Sunshadow. A high quality drill sharpener is well worth the cost to have accurately sharpened bits.
 
If it were me, I would buy a dozen pack of cobalt bits. (and learn to sharpen them.)
Page,
I am surprised, I learned to sharpen by watching a machinist do it ONCE. Since then I have done it on my bader grinder; M-2 Cobalt, even carbide.
I do notice that my holes tend to run about .001" oversize after I sharpen them, but hey if I want more accurate than that I will drill undersize and ream. For me a drill doctor would be a silly buy.
Thanks,
Del
 
Come on folks, don't make this harder than it has to be....

Listen to Nathan The Machinist!

Everybody is telling you use lube and go slow. While there is some truth to this, it can be over done. The most common mistake I see with inexperienced people is not feeding hard enough, and just letting the bit rub. That's bad.

Use WD40 (only thing its good for IMO), oil, water, lard, soap, whatever, you're trying to keep the cutter cool! The lube just isn't that important (not so with a tap though!) The purpose of pecking is to break the chip and let coolant down into the hole.

500 RPM isn't too fast for a 1/8" drill. I'd probably drill that, in 1095, at about 1000 RPM and 3 inches per minute feed rate with a water based coolant. You spin faster with small bits, slower with big. If you're getting chatter, you're feeding too slow or running to fast. You want your periphery cutter speed around 40 surface feet per minute. Do the math. 150 is bad (in tool steel), 20 is pointlessly slow.

The last thing you want to do on a carbide laced steel is pause on the hard bits and let it eat up your cutter. Lean into that thing!

Wear safety glasses. When you're machining right, you're really not that far away from breaking something!
 
Well said nathan. i think its ridiculous to throw away a dull bit, when about 15 seconds at the grinder will have it sharper than new after a little practice. would you throw away a knife the first time it got dull? i should hope we can all look at the edge geometry on a drill bit and put a new, sharp edge on it. thats what we make, sharp things!
-Lou
 
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