Need to add pin holes after hardening... oops!

Sebspeed

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Need to add pin holes after hardening... help!

I'm making a knife for my father for Christmas, shaped a blade from 440C and hardened & tempered it. Brought it from 21.4hrc to 58.7hrc. And then realized today that I'm not going to get holes in it with my TiN coated bits...

Any suggestions?

I've looked at carbide tipped drills, but would likely have to order them in and that might take too long. I have a TIG welder and considered heating the area I want to drill, but that will ultimately heat the whole knife as well.

Here's a picture in case it helps at all.

pre hardening

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post hardening

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Only option I know of is to anneal drill then re HT either that or carbide bits. Call your supply house and ask the cost of expidited shipping. Or find a local source. Fastenall or Master Craft come to mind
 
Best thing that I can think of is going to some outlet like Carbide Connections and see if they have expidited shipping or sticking the blade in a can of wet sand as a heat sink and taking a propane torch to the tang. You probably won't, and wouldn't want to, austinize the tang but you may be able to reduce the hardness in the steel enough to drill through the tang. I would also replace the bit(s) that you used if there is any chance that you overheated them. Also use some cutting oil when you drill and keep the speed as far down as you can. BTW, you're not the first person to do this. I was austempering a knife that I made from some 52100 and forgot to hold the tang out of the quenchant until the color left it. I was able to use the blade in wet sand trick with a propane torch but I still shot the bit that I was using by the time I drilled both of the holes that I wanted.

Doug
 
No need to get too fancy or complicated. Just go to your local hardware and get some carbide tipped masonry bits.
Add a little cutting fluid, and drill away.

Just start slow and with light pressure so the bit doesn't walk all over the place, and once you make that first little dimple, you'll be good to go.
 
Just keep in mind that a 1/8" masonry bit is going to drill a hole that's slightly bigger than 1/8". Not really a problem if you are drilling your scales with a regular twist bit. I figure this just gives a little more room for epoxy around the pins.

Also, be sure to go slow when exiting through the bottom, or you might have some chip out. Again, not really a big deal, unless your drilling a really narrow secion of steel, as it really just gives more room for epoxy.
 
You can spot anneal. Wrap a wet rag around the blade to act as a heat sink. Heat with a MAPP gas torch and while the spot it still red hot trow it on the drill press and drill with a lot pressure and speed. You can kiss the bit goodbye after a couple of holes but you can drill it that way with a regular bit!
 
I was able to get the holes added. You can pretty much forget drilling this stuff! Lesson learned!!

Now to get this bad boy finished.

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