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  1. #1
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    Help! How do I drill hardened steel?

    I'm making 3 or 4 little thumb knives from Eclipse power hacksaw blades. I'd like a 6mm lanyard hole but my cobalt bits won't touch it. I already shattered one by stupidly trying to put too much pressure on it, hence 3 or 4! It was 5!

    The only bits I can see online are for tiles and glass, and are flat ended with diamond grit. I asked the seller if they would do metal and he didn't really know, but said they would probably wear quick and I should buy a few.

    Any advice out there?
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  2. #2
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    Re: Help! How do I drill hardened steel?

    I would try annealing the end of the blade. Use localised heat and get it red hot and allow it to air cool, then try your cobalt drill again.
    Good luck anyway

    Chris
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    Re: Help! How do I drill hardened steel?

    Like the man says, heat with a torch until cherry red and let it cool. I did this and found that it did soften the handle to redrill. But only after trying to heat the handle up on my gas cooker - really didnt do it, so I bought a butane or propane (cant remember which) torch from B&Q. That sorted it really quickly.

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    Re: Help! How do I drill hardened steel?

    Solid carbide twist drills. Sold here:

    http://www.mscjlindustrial.co.uk/cgi/insrhm
    Last edited by Iron Hoarder; 06-06-09 at 12:03 PM. Reason: Added link
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    Re: Help! How do I drill hardened steel?

    I'd try annealing too, but if that doesn't work you could try grinding through it with a burr and a Dremel-type tool.

    arian

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    Re: Help! How do I drill hardened steel?

    Quote Originally Posted by Iron Hoarder View Post
    Solid carbide twist drills. Sold here:

    http://www.mscjlindustrial.co.uk/cgi/insrhm
    Will these really do it Rob? 'Tis hard stuff. If they do then this is the way forward.

    Thanks to all, I think it may make sense to soften it, my only reservation being where I have sanded the paint off I have been left with a lovely blue/black/mirror patina which will burn off. This blue will be picked out in the tiny blue scales being fitted.

    Arian, thanks, I have tried grinding a hole, but this steel laughs in the face of Dremel bits. It will go through, but it's not practical for producing several holes all equal.
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    Re: Help! How do I drill hardened steel?

    I read this thread with a couple of glass/tile bits laying beside the computer.

    Thought I'd give them a go. Most, if not all, the machine-size hacksaw blades I've come across have been all-hard HSS. I didn't have one to hand, so tried drilling an HSS lathe toolbit with a tubular diamond-grit drill and with a spade-type carbide drill.

    Both will probably work on the hacksaw blades. I got hacksaw-thickness depth or better in the 1/2" HSS with each bit. I used the lowest speed on my pillar drill, about 250 RPM, and used plenty of oil to cool/lubricate.

    I had everything clamped up tight so it wouldn't move at all. For a hacksaw blade, I'd back it up with wood. I started with the spade bit and moderate feed pressure, then changed to the diamond bit and moderate feed pressure for a new hole. Both were very slow. 5 minutes with each gave the impression that half-an-hour per hole would be optimistic for a hacksaw blade.

    I changed back to the spade bit, relocated the original hole and applied immoderate pressure. This worked very effectively, producing needle-like swarf and making surprisingly rapid progress. I backed out and squirted in more oil a couple of times, before breaking the bit. I think I'd probably let things get too dry and I was just easing the pressure to back out and oil, when it broke.

    I then fitted the diamond drill again and tried that with lots of feed pressure. Again it was better, but it was much less impressive than the spade-type bit.

    I'd say try the spade-type glass-and-tile bits. Get extras though. Plenty of oil. Rigid setup and lots of pressure. If you've not got a pillar-, or bench-, drill, I doubt you'll get the feed pressure.

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    Re: Help! How do I drill hardened steel?

    I have drilled many hole in hardend 440c(RC 58/59) or 154CM(RC 61/62) with either solid carbide twist drills or with carbide tipped Spade drills. I have put holes in both steels with a carbide burr in a dremel tool
    Dave
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    Re: Help! How do I drill hardened steel?

    Use plenty of lube and slow speed and the carbide bits will work.
    Whoever dies with the most tools wins.......Now accepting donations.
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    Re: Help! How do I drill hardened steel?

    I've used (and given) many of the tips above, but the best advice is to avoid it altogether. You should fully anneal the piece, find a way to avoid drilling, or choose different donor steel.

    I'd decide to drill through hardened steel only when I have considerable time and materials invested in a knife and never when contemplating a new project.

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    Re: Help! How do I drill hardened steel?

    Depending on the size you want.I use a Dremel carbide bit in Drill press with a little oil to help cool it.I enlarge the hole with a choice of diamond burrs to get the size wanted.

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    Re: Help! How do I drill hardened steel?

    When you anneal the handle:

    1) Does it also soften the blade near the hilt?

    2) Does the handle need to be re-heat treated afterwards? How?

    3) Will a simple propane torch with canister generate enough heat to anneal it?

    4) Will annealing cause a layered/sandwich-type blade to disbond? I presume not but need to ask since I want to drill into a layered Fallkniven blank. Heating up to a red hot state seems awfully hot.

    thanks
    Last edited by cncyana; 09-06-09 at 07:11 PM.

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    Re: Help! How do I drill hardened steel?

    I have not tried this but a friend told me, when we were discussing this same problem some time ago-- I'd like to put a thumb stud on a Buck 110-- that he has achieved a spot-local anneal by running a bit on the spot where the hole is to be until the bit heats to red and the workpiece does, too, in that area. This might (key word) work with thin stock. Good luck.

  14. #14
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    Re: Help! How do I drill hardened steel?

    Quote Originally Posted by ZDP-189 View Post
    I've used (and given) many of the tips above, but the best advice is to avoid it altogether. You should fully anneal the piece, find a way to avoid drilling, or choose different donor steel.

    I'd decide to drill through hardened steel only when I have considerable time and materials invested in a knife and never when contemplating a new project.
    Oh, you killjoy Zed!, A little thumb knife needs a bit of paracord through a hole. It's probably sound advice though, but as it's only recycling hacksaw blade, I think I will try a carbide bit and see what happens.

    Quote Originally Posted by Miles Undercut View Post
    I have not tried this but a friend told me, when we were discussing this same problem some time ago-- I'd like to put a thumb stud on a Buck 110-- that he has achieved a spot-local anneal by running a bit on the spot where the hole is to be until the bit heats to red and the workpiece does, too, in that area. This might (key word) work with thin stock. Good luck.
    And this sounds mightily dubious, but quite fun. As I have a blunted cobalt bit, I'll have a go. Ping goes another little blank I think, but never mind, it's all learning.

    Thanks to all for some good advice. As I haven't got a pillar drill, I can't report straight back on my progress, or lack of. But I do intend to make some holes one way or another.
    Warren Earp: Wyatt, you're still a marshal around here, aren't you?
    Doc Holliday: Sure. But now he's going to be a marshal and an outlaw. Best of both worlds, son.

 

 

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