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Jon Fisher

Issues with drill bits in 1095

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Hey all, 

Thanks for the add. So I am burning up some drill bits on 1095. I have my speed at 550 RPM. Any advice on a good bit that will last at least a bit longer and feedback on my speed. Appreciate the advice in advance.

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Did you try to anneal the 1095 by slow-cooling in vermiculite/ash/lime/other slow-cooling medium?  If so, you created lamellar carbides that will eat drills for a snack.  A plain old air cool is all you need.  If it was hardened 1095 you need straight-flute carbide bits.  Last option, if your first bit was dull and not producing chips, you may have spot-hardened where you're trying to drill.

Give a bit more information and we'll be more helpful.

And welcome aboard!

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It was air cooled after every heating up while forging, but not quenched. Makes sense on maybe a hard spot but would that do that on only aircooled? I'm basically drilling holes before the quench for handle construction. Is the speed too low or high? I tried a few different speeds, no go. Have not tried  straight flute carbide bits, but I will. Any particular brand better than others? I'm a beginner and have not attempted 1095 before, so any advice would be helpful. Sorry cant give you more details other than what I said above. 

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Heat the steel red hot but below critical and let it air cool, you could be getting some air hardening but if you keep the heat below hardening temperature you wont get any hardening, I believe the term for this is "subcritical anneal" but im no expert so im going to read about it a bit.

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I've found that cheap HSS bits, even the coated ones, don't perform very well on high carbon steels.  Given my cheap equipment, carbide drills aren't worth the investment for me.  I've had my best luck with cobalt drills.  Turn them as slow as your drill press will let you, lubricate the hell out of them while drilling , and provide a nice constant pressure.  I use tapping fluid as a lubricant, 3-in-1 oil works as well.  Stay away from WD40, it doesn't work anywhere near as well.  Take it slow and easy and you should be able to drill through unhardened steel without an issue.

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What Steve and Alex said.  And get rid of any scale before drilling, scale is harder than glass.  I get the Irwin cobalt bits from my local Ace Hardware, a couple at a time in the size I want.  As long as your steel isn't hardened they will do the job, for a dozen holes apiece at least.

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2 hours ago, Alan Longmire said:

What Steve and Alex said.  And get rid of any scale before drilling, scale is harder than glass.  I get the Irwin cobalt bits from my local Ace Hardware, a couple at a time in the size I want.  As long as your steel isn't hardened they will do the job, for a dozen holes apiece at least.

Those are the same bits I get.  You are definitely right they will not drill through scale.  I found it to be extremely tough going.  Sometimes I was successful a couple of times I wasn't even able to get one hole drilled all the way through.  Scale will also dull the bits come to find that out the hard way.  Had to buy a new bit.  How ever if you are drilling on forged mild steel you can still drill through with scale on it I found success with that.  But harder steels like the 1095 which I've never used I'm sure it's much harder.  Alan I think I will definitely take that advice for the next blade I make or anything else I make for that matter.

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Thanks to everyone. I did the whole sub-critical heat then air cool and it worked. I bought an Irwin cobalt bit and went through the second hole like butter. First hole must have been hardened. Now I'm stuck with a edge that keeps rolling. Time for a second quench I guess.

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