Cobalt bits won't do it--looking for advice

Fish30114

Fish30114

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Jan 5, 2014
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I recently completed my first knife, and one of my buds like it so much that he has given me a blade he wants handle scales put on. It was one of those knives that had a molded rubber handle, I guess they poured/molded around the blade, but long story short, I cut/ground the rubber off of the blade, but the blade is already hardened, and I cannot seem to drill it at all for the pins for wooden handle scales. I have Norseman magnum (cobalt) buts and they can't make a dent in this stuff, it is marked 440C, but it was a cheapo blade, and I don't really know if that marking is accurate.

Looking for advice on how to get this thing drilled--wanting to use 1/8 pin stock.
 
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I've annealed hardened carbon steel tangs by holding the blade by pinching it between my thumb and finger at the ricasso area. I keep the blade in a bucket of water with the ricasso and tang above the water. Then torch the tang where I need to drill it. When the heat starts to reach my fingers I dip it a little lower in the water to keep the heat away from the blade. I've gotten good results by torching it good and hot, holding it at temp for a bit, then slowly moving the torch farther away so the tang doesn't cool too fast.

Again, this works well for carbon steel, but since I've read that small pieces of 440c will air quench, it my be useless for you...
 
Well thanks Jesse, I was thinking this may be worth a try--can't figure why a cobalt bit won't handle it....
 
if you dont need the hole to be perfectly sized a Masonry bit spun FAST will cut the hardest steel (be warned it WILL destroy the bit also, and don't expect nice tolerances)
 
That is because the bits you have are HSS, not carbide.

The "special" coating on them makes them last longer for regular drilling, but is far below carbide in hardness. They use all sorts of tough sounding words, like "Super" "Special", Magnum" "Premium", etc. to make them sound like they are really superior drills that could drill through diamonds ... but they are just good drill bits, not carbide.

Get a 3/16" carbide bit and it will drill through the hardened 440C.

It is best to put a backer piece of mild steel under the blade when drilling to avoid damaging the fragile carbide bit when it comes through the backside of the tang.
 
Ditto on what Stacey said. I have used locksmith carbide bits very successfully when needing to drill hardened steel. Stacey's suggestion to use a backer under the workpiece to protect the fragile carbide bit is one that I will try from now on as I have snapped a few and they are not inexpensive!
 
Thanks Stacy, I actually edited my first posting, the drill bits I have are Norseman Cobalt bits--I will get a Carbide bit and give that a whirl--I'm rather disappointed, I did a bunch of looking and asking online and these bits were highly recommended--I actually bought two sets of them. :(
 
Great information in this thread, I love my norseman bits but hardened stainless has been an issue for me as well.
 
They're good bits, cobalt is a superior HSS.

They're not good for drilling hardened steels, only carbide is up to that.
 
Fish30114 said:
Thanks Stacy, I actually edited my first posting, the drill bits I have are Norseman Cobalt bits--I will get a Carbide bit and give that a whirl--I'm rather disappointed, I did a bunch of looking and asking online and these bits were highly recommended--I actually bought two sets of them. :(
Click to expand...

Stacey is right. When I first started doing knives I bought similar "cobalt" and carbide tipped drill sets. They wear out fast on hardened steel and eventually all they do is generate heat.

All I use now is carbide bits coated with Altain or TiN. They cut through anything like butter. And carbide likes to be used at a high rpm.

Just make sure they are 100% carbide.
 
i always have a few carbide endmills handle in differnt sizes. then again i have 2 mills and collets sets ballend mill bits are nice for dimpeling parts adn if carbide drilling hardend steel (just make sure they are center cutting)
 
I can get masonry bits cheap at the local hardware, but I find that though fast is good, if I try to lean into them and they heat up, the carbide tip falls off right now- so I kind of peck at it and try to be patient, lifting the bit out so it can cool and only drilling for a second or two at a time, and it goes through pretty quick, though not as quick as I'd like.
Seems like the tips are brazed on, so you can't get them very hot.
Nowadays I just keep a handful of spendy carbide bits on hand in the sizes I need, but those hardware store ones will get the job done.
 
I use carbide bits and go slow with plenty of fluid lube. Be sure to have the piece in a vise that is locked (clamped) down! When the drill point is just breaking through, reverse the blade and finish the hole drilling from the opposite side. Another trick, have a wood block clamped along with your tang where the drill bit is going through. Wood block must be snug against ( under) the tang where the hole is going to be. As the bit goes through the hardened tang, the block will help the bit to not grab. Go slow. The wood block has to be tight against the tang.

On other occasions, I have used mild steel under the intended hole ( in place of a wood block) and it works good. Even with going slow, be aware of getting the bit too hot, hence, the lube.

Some use carbide Dremel bits, as well as carbide mill end bits, as I also have.

What Stephen said works too, and those bits are pretty cheap.
 
Against the heat just drill under water.
I'm using an old frying pan. Have the piece in there slightly covered with water and you can keep drilling away without the piece getting warm or even hot.
Of course you can't clamp it in there too well but even if the piece starts spinning it'll be highly unlikely to penetrate the frying pan's wall.
 
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