The painful death of my drill bits

oic0

oic0

Joined
Jun 16, 2012
Messages
368
What kind of drill bits do you guys use? I am drilling before heat treat and it still destroys my bits, thats with a slow speed setting and squirting water on them as I go! Also, this is on 10xx series, not air hardening stainless. 1095 especially has been giving me fits. One hole will go through nicely usually then the next one starts squeeling, by the third its an ear drum destroying no go. Brand new bits, old bits, varying brands.
 
I recently had some 1084 that gave me fits, New Hertel Cobalt bits saved my day.
CW
 
are you using CRA or HR 1095? If it's not pre-annealed, you're going to have problems.

I'd probably try a dedicated cutting fluid rather than water as well.
 
1095 HR (hot rolled) can be very hard. It is hot rolled and not annealed. Like s2f said it is a good idea to do an anneal just for good measure. If you have 1095 cra or hra ( cold rolled annealed or hot rolled annealed) you should be good to go but I still do an anneal before I work it esp before I HT. Also use a good cutting oil NOT water. WD 40 is NOT a good cutting oil for steel. I have seen some at our local hardware stores. I use LPS #1 Gold for all my cutting unless I am cutting Titanium then I get a heavier oil. Keep the speed at the correct RPM for the drill bit and material being used, also keep up the pressure, do not let it dwell in the hole. This could work harden the material. Not good. If the bit starts to squeel stop and figure out what you are doing wrong. Do a spot anneal with a torch and try again. With proper technique a good HSS or Cobalt drill bit will last for 100s of hole even in some pretty tough stuff.
 
I feel your pain...go with cobalt and cutting fluid ( I've been using wd-40 with no probs but I will check the other stuff too)
 
I just killed two new 1/4" titanium nitride bits drilling six holes into a knife tang made from ~1/4" thick 1084. I was using wd-40 for a cutting solution, as that and 3-in-1 are all I have in the lubrication department. I was using moderate to strong pressure like Nathan's thread suggested. Are they just cheap bits? They are a name brand from Home Depot (can't remember the brand but they came in a lime green box). Or was I doing something wrong? I've been reading through all of these drilling threads but haven't found my answer yet. Should I have drilled the holes with a smaller bit and just worked my way up to the 1/4" bit? If so, then what size should I start with and in what increments should I proceed? I have drilled many, many more holes with the 3/16" bit that came in the same set, and it's still going strong.
 
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Broom
Hertel cobalt bits, if you get a good bit you dont need to step up in size for a 1/4 hole.
CW
 
even cheap bits should eat up soft 1084, if you're not pulling ribbons of steel you're not using enough pressure and you're dulling your bit in the process
 
+1 on Nathan's thread! Good stuff!!!

HR 1084 and 1095 can be an absolute PITA. Normalizing one to three times will make life much easier and ya get a better blade as a bonus...
 
i use cobalt bits and wd40 like so many others on this thread =) works wonders and i go slow. good luck =)
 
I've drilled many many holes through Stainless (mostly 316 and 309) and Mild Steel (some 1 1/2" thick) and never had any problems as long as the bit was sharp and I used a good cutting fluid. Have you looked into union butterfield tapping fluid?

When you all are saying that your bits are "ruined" are you meaning dull? or is the bit in pieces? It's real easy to sharpen a bit, and it's real easy not to break them.
 
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I use regular black oxide coated HSS bits from MSC with no issues. If I run into a hard spot I stop and spheroidize it. I always centerpunch first so the drill has something to grab at then feed it hard at slow RPMs and get several years out of a drill bit

-Page
 
Killed as in badly dulled and very slightly disfigured. They can be sharpened and be good as new, just thought I should get more than 6 holes from two bits.
 
oic0 said:
What kind of drill bits do you guys use? I am drilling before heat treat and it still destroys my bits, thats with a slow speed setting and squirting water on them as I go! Also, this is on 10xx series, not air hardening stainless. 1095 especially has been giving me fits. One hole will go through nicely usually then the next one starts squeeling, by the third its an ear drum destroying no go. Brand new bits, old bits, varying brands.
Click to expand...

you need to drill at a slow speed and use wd-40 as a cutting oil and that should sove your problem. when I was drilling I-beams on a job site I did just that and the drill bits lasted a very long time.
 
I bought a drill doctor a couple of months ago to try to save some of my bits but the learning curve on proper operation appears time consuming and I just haven't had enough time. Some folks swear by them and I will report back after I have spent some tme with it.
 
I just had this problem with some 1095/L6 Damascus- I refused to believe that what I really needed to do was a slow cool anneal, rather than a quick normalize/subcritical anneal, and thus ruined a 3/16 bit and a reamer. Funny how taking the time to do that made it all betta.
Andy
 
I recommend a good fairly complete USA made cobalt drill set and a Drill Dr. I did that about oh 12 years ago I guess now and still use pretty much the same drill bits just resharpen when needed. I've noted on more than one occasion that it is not so much the drill bits fault when it ruins as it is the operators. Its your job even at a slow speed to allow the bit tip especially to cool and keep it from burn marking. Back out of the hole instead of forcing it on through. Take the holes down in stages not plunge down through it. Also, I've found that starting smaller holes first, call them pilot holes seems to work very well for extending the life of drills especially drilling titanium. For my pry bars with the final 7/32 drilled hole for the para cord and the 3/16 size for the lower hole I always drill the first holes with a 1/8" then follow with the 3/16" then on the one I do the 7/32 and again these are staged drilled holes not forced through making it bind and heat up. I counted up once how many drill holes I have done with that one single 7/32 drill doing this this way and its well over 500 holes with one drill bit so far and I still use that same drill.

Oh and I personally stay away from the bits with the weird pilot thing because its hard to sharpen them with the drill doc so I just stick with the old style twist cobalts and have had no trouble doing this. I don't use any lube on my drill bits whatsoever. Never have and I get great life out of them drilling a lot of titanium .90 thick and even more .045 thickness so I'd say slow down, keep the bit from getting hot and you'll have a lot less trouble. The trick is tuning in to your work so you watch and know when to back it up and give it few ticks to keep from getting too hot. Sometimes I'll flip the piece I'm drilling and come in from the back side if the drill seems to be reaching that point where I need to pop it out and touch it up on the drill Doc. Anyway, thats how I do it. May not be ideal but it works for me.
 
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