Could use some Advice!

I fashioned my Bowie blade from a leaf spring and am drilling holes now for the brass bolster, handle pins, and brass end piece. I drilled the first few starting at the blade end and worked down the tang. The holes drilled without any problem. The next 2 holes will not drill! The blade was only heat-treated down to the ricasso area, so tang was not ever hardened. It was tempered x3 in the oven to straw brown color. The tang is soft to a file. I heated the area around the holes with a torch, as you can see, but it did no good. The drill bit won't go into the metal just for these 2 holes. I tried several different bits, no help. In the picture you can see the remnant bolt hole in the tang from the leaf spring which is now closed, but interestingly the 2 holes I am trying to drill are on either side of this.
Any idea what may be going on? Would appreciate any input. Thanks, Brian
 

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John Wilson

Well-Known Member
if you chuck it up in a vise, you can use a torch to heat the trouble spots to a red heat to anneal the area. the vise will act as a heat sink. the blade will not be affected.
 

Chris Railey

Well-Known Member
A new carbide bit will get through. Next time it may be better to go in this order. Forge—clean up profile—normalize x2–drill holes for tang--grind—Heat Treat. It will not guarantee you will not hit a hard place when drilling your tang but it should lessen the frequency nicely.
 

chrisstaniar

Well-Known Member
Get a cheapo masonry bit. It's carbide and will drill through. Then just throw it out as it will be ruined, but they only cost like a buck or 2.
 
Thanks everyone for the input. I'll try the masonry carbide bit first and see how it goes. The true carbide bits are about $20. Never would have thought there would be isolated hard spots like this, but pretty new at this.....
 

Jon Buescher

Well-Known Member
Thanks everyone for the input. I'll try the masonry carbide bit first and see how it goes. The true carbide bits are about $20. Never would have thought there would be isolated hard spots like this, but pretty new at this.....
I’ve had good luck drilling stuff with Irwin brand cobalt bits Ace hardware specials. Cheaper than cobalt. Don’t buy the set, just get a couple of the size you need
 

One Armed

Well-Known Member
I know this is kinda old, but I typically buy ONLY M42 Cobalt bits. Amazon, you can find whatever size you need.... usually in singles or 5-6 packs for pretty cheap. M42 is nice because it will go through nearly anything, but still pretty easy to sharpen. And on that not. If you haven’t, learn to sharpen. I taught myself to “Correctly” sharpen a drill bet a few years ago. I used to think I knew how to sharpen....until I learned my current technique.

Here’s an M42 bit that was dull as a butter knife. I sharpened it, & now it’s like a laser scalpel! You can see my technique leaves a proud bevel apart from the relief angle.


What size did you need? I may have a spare M42 bit with my sharpening, I can drop in an envelope and mail ya. Let me know?
 

Alden Cole

Well-Known Member
I know this is kinda old, but I typically buy ONLY M42 Cobalt bits. Amazon, you can find whatever size you need.... usually in singles or 5-6 packs for pretty cheap. M42 is nice because it will go through nearly anything, but still pretty easy to sharpen. And on that not. If you haven’t, learn to sharpen. I taught myself to “Correctly” sharpen a drill bet a few years ago. I used to think I knew how to sharpen....until I learned my current technique.

Here’s an M42 bit that was dull as a butter knife. I sharpened it, & now it’s like a laser scalpel! You can see my technique leaves a proud bevel apart from the relief angle.


What size did you need? I may have a spare M42 bit with my sharpening, I can drop in an envelope and mail ya. Let me know?
Not to hijack the thread, but would you mind sharing how you sharpen your drill bits? Thanks
 

One Armed

Well-Known Member
Not to hijack the thread, but would you mind sharing how you sharpen your drill bits? Thanks

I can, it’s just difficult to explain in text. I’ll try to put together a video and link it here, if no objections? Or I’ll just PM you.

:Edit: I found the main video that I learned this technique. Let me know if you don’t understand. Fast forward to 11 minutes into the video for the procedure.
 
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One Armed

Well-Known Member
Right on brother! Glad to hear it. Yes, as I had said I “thought” I knew how to sharpen bits pretty good....that I saw that video & it was quite an eye opener. I’ve taken that basic technique and modified it just a bit to my own. I’m sure you’ll do the same. Just so nice to always have a super sharp bit. I used to spend a small fortune on replacement bits. Now I buy the size I need as I need it, in M42 Cobalt. And I have it forever. Good stuff.
 
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