Drill bit broke while drilling through the guard

Jim Rieck

Jim Rieck

Joined
Jun 4, 2010
Messages
71
Oh baby!! I am sure I am not the only one that has done this, but how do I recover? I was drilling pin holes through the guard and the darned thing snapped and left part of the drill in the hole. Does anyone know how to take it out?
 

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Drill a smaller hole from the other side. When they meet, punch the broken drill out, then finish drilling the original hole.
 
You of course can grind off the guard and make a new one. OR if the bit is deep enough where it broke. , leave it and place a pin over top and peen it in place \. Now drill a hole from the other side and place a pin in here to match. Frank
 
I've done both of those fixes. This has happened to me a few times- sometimes it can be saved and sometimes not. I'd go with the first method. Good luck, I HATE it when this happens. The worst part is sometimes the snapped bit fragment will stick the guard to the blade. What a PITA. I also filled the top of the pin hole with solder once with OK results. I'd not recommend it for a knife you are planning to sell, however.
 
I tried to drill a smaller hole, but couldn't get it through. I ended up grinding off the guard, but that leaves me with two blind holes in the tang. I'll try to drill blind into them, but, I fear that this blade is going in my wasted blade drawer. Such is the life of a knifemaker, I guess. Not every one is a total sucess story. More at 11:00. I should mention, though, that I fit my guards long before heat treat (how do you drill holes otherwise).
 
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Are you using a drill press or a mill to drill your holes? You can match the hole with a drill bit in a mill then take drill bit out and put a center drill in its place without moving the blade. Slide new guard up onto blade and use center drill to start hole. Replace with your correct drill bit and then drill through. Should match the hole.
 
Thanks for the advice, guys. I really appreciate it. My shop is still humble and I am using a drill press for my holes. So what I will have to do is fit a new guard (old one just isn't the same after grinding it off) and measure as best I can with calipers to match the holes in the tang. I am hoping for the best.
 
I was tapping some holes for a pocket clip on a Titanium handled knife when the (2-56) tap broke. I soaked the handle slab in battery acid until the tap dissolved. You might want to switch to Titanium guards.
 
tiguy7 said:
I was tapping some holes for a pocket clip on a Titanium handled knife when the (2-56) tap broke. I soaked the handle slab in battery acid until the tap dissolved. You might want to switch to Titanium guards.
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Because then you could dissolve the blade and drill, but save the guard !!!
 
You guys are funny. Given the posts on the troubles with titanium (and the cost), I don't think I'll be making guards out of it anytime soon. Also, after some investigation and drilling a couple of more guard pin holes, I have decided that I bought a batch of bad drill bits (1/8 HSS USA 297). I think they were a bargain? The outside of the cutting edge chips out while drilling my 303 stainless guards and through either D2 or ATS-34. That's when the chucking sound begins and an impending break is near.
Anyone know a reliable vendor of good drill bits?
 
DeWalt Cobalt bits are awesome, I don't use any other bits. Being name brand most hardware stores should have them.
 
Use the holes in the tang.
Get another piece of guard material, not slotted and use the holes in the tang and drill through to the guard material. then finish as usual.
 
Jim Rieck said:
You guys are funny. Given the posts on the troubles with titanium (and the cost), I don't think I'll be making guards out of it anytime soon. Also, after some investigation and drilling a couple of more guard pin holes, I have decided that I bought a batch of bad drill bits (1/8 HSS USA 297). I think they were a bargain? The outside of the cutting edge chips out while drilling my 303 stainless guards and through either D2 or ATS-34. That's when the chucking sound begins and an impending break is near.
Anyone know a reliable vendor of good drill bits?
Click to expand...

I'm going out on a limb here, but are you by chance drilling through the guard and the blade at the same time? I was taught that when you drill two pieces of metal stacked on top of each other, that the difference in stress relief from when you breach the top piece and enter the bottom can cause binding issues which can snap the drill. Might not be an issue, and might be totally common knowledge, but I thought I'd mention it just in case it could help.

As far as which brands I can recommend, I never had any problem with Irwin (Irwin Industrial Tool Company ). They're a little spendy, but I never had one break on me.
 
It's true, I find that if drilling through the guard into the blade, I have bit snapping issues. I try to drill the guard all the way through first, then hold it on the blade to mark the holes with the drill press. I then take the guard of again to finish drilling the holes in the tang.

I usually fit guards after H.T., as I finish sand the blade post-HT and then try-fit/file the guard to fit, then drill the guard holes, then drill the blade. I just use a cobalt bit, keeping it sharp as needed by resharpening, and going slow.

One thing you can do is drill the blade, HT, cut the slot in the guard stock, file to fit the blade, then clamp or temp. super glue the blade on top of the guard, using it as the template marking the guard holes for drilling. I don't do this much, it's a bit of a PITA.
 
My Dad the clokemaker, always stressed that when drilling precise, small holes (usually in a watchmaker's lathe) DO NOT use the "good" HSS drill bits. When you break a drill (not if) you can use a hardened punch to break up the drill bit into fragments that can be extracted from the hole. Unless I am dealing with a tough material, such a questionably annealed steel, etc., I prefer the carbon steel bits, they are cheap enough to throw away as soon as they start to chatter, although they can be resharpened, but I am not sure it makes dollar-sense. I always bought such from MSC.
 
Thank you guys for the input and good advice. The tip about not drilling through the guard and tang at the same time is "NOT" common knowledge. I plan on changing my technique there as a start.
 
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