Drilling help

S

sfoo

Joined
Dec 3, 2002
Messages
42
I am a newbie at making blades, so be nice to me :) I know I have done a number of things out of order, but it's a learning process and the next few will get better. I've gotten to the point of fitting the guard now, and am having a bit of difficulty with it.

In any case, I'm trying to drill a 3/32" hole through a blade of O1 steel that, of course, I've already hardened and tempered. I bought a new Cobalt bit to try and drill with, and after about 10 minutes of trying I made a small indent (maybe 1/64"). At this rate I'll be here for about 2 years and a new drill press. Used cutting oil, tried slower speed (600), faster (1800), nothing seems to make a difference.

Without rehardening/retempering, can you suggest a way I can get this hole through the blade? Or am I going to be stuck doing the heat treat again?
 
You'll have to go with carbide bits for hardened steel. All you're going to do is ruin your cobalt bits. If they squeek you've already ruined it. You know now to drill before heat treat. :grumpy:.

Roger
 
Probably gunna have to anneal that section, or maybe get a diamond bit...;)

Good luck, others here will probably have more insight than me.
 
One other way is to use a masonary bit, if they have it in the size you need. Use lots of lube.:eek:
 
Craftsman Zirconium nitride, lots of oil, and back it out frequently to let everything cool and clean out all the metal chips/shavings. And lots of patience.

I made same mistake with O1 last week. Luckily it was edge quenched so wasn't fully hard there. :) But it was a pain
 
I use carbide bits with plenty of oil and drill very carefully while watching the heat buildup. Be SURE to have blade in a vise! Another thing, go extra slow and careful when at the end of the drill hole where it is going to punch out to the other side, or your bit will grab and snap or chip. I've turned the blade over in the vise and finished the hole from the other side as soon as the bit has just started to exit. You will see a pinhole at the bottom of the hole, then flip it over and finish hole. I should add here to C-clam vise down while drilling, or you are asking for trouble.
 
I once went through five drill bits on a D2 blade after heat treat. Eventually I just cut a slot in it with a narrow blade on the angle grinder, then put a pin in at each end of the slot. It held. (shrug)
When cutting tools don't work, all we have are acids, heat and abrasives.
 
I have responded to similar posts in the past. The thing that I use in this situation is Hi-Roc carbide bits from MSC. Do not attempt to use carbide spade bits. They are made for drilling thin materials only. The bits are expensive, but will do the job when nothing else will
 
I managed to get my hole drilled with a carbide drill bit. Enco sells small bits for pretty low price. Good thing since one broke when it broke through the opposite edge. In any case, hole drilled, guard pinned, on to the finishing stages.
990-3146 USA 3/32 1/8 SH.X 1 1/2 C.B.DRILL 249 $3.42
 
Thx.

John was wholly correct. :) I was even trying to be careful with it and it still snapped. Oiled it, ran it at 260 rpm, cut quite nicely most of the way through.

Lesson learned: Drill before hardening!
 
Drilling sucks. I've got a hidden-tang knife that I drilled the other night. I broke a tip off in it, and thought I got it all out. After that, I went througha masonary tip, cobolt tip, and even my precious carbide tip. Finally took it all apart to find a piece of drill bit still in the hole. I drilled it through the other side in about two seconds. :grumpy:
 
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