I Feel like an idiot

Matt Rochester

Matt Rochester

Joined
Nov 28, 2014
Messages
1,864
So, just HT'd a batch of 7 knives in CPM 154. Everything went great. After cooling them off after the first round of tempering, it hit me. I forgot to drill my holes in the tang. I feel like such a rookie. Wait, I am a rookie. Anyway, what now? Should I anneal, drill and redo my ht? Is it worth trying to spot anneal? Order some carbide bits? They are at about 60rc.
 
I'm sure it happens to everyone at some point. Happened to me. Probably will again.

Something I didn't try that I thought would be pretty slick is chucking a metal rod in your drill press and using that to heat up and anneal the areas you want to drill for pins. Should get red hot and I imagine you could control the heat from spreading fairly easy.

I tried the masonry bits and in my experience I might as well have chucked a metal rod and saved the money on the bit.

In the end I ordered a spade tip solid carbit bit with no flutes and used it at a high rpm, maybe 2000, with no cutting oil. It cut through hardened AEB very easily. I think I paid $15 on amazon for it.

-Clint
 
You won't anneal CPM-154 by getting it hot and letting it cool - it is an air hardening steel. It is fairly difficult to anneal well without a good HT oven and long programs.

What you need is a carbide drill bit. The standard ones are expensive, and fragile, but every knife shop needs them. A 1/4" carbide bit is pretty much a necessity. What works in a pinch, and is much cheaper is a carbide masonry bit. It is slower, and will heat up the tang a lot, but works. The best way to use one is to clamp the blade in the drill press vise, and make a dam of putty or clay around the hole to be drilled. Put some cutting fluid or water in the pond made by the dam. Drill on low to medium speed with lots of downward pressure. Use a pecking motion of down 2,3,4,5,6 - up 2-3 - down 2,3,4,5,6...etc.
 
I have some masonry bits I have used on other knives but never ones this hard. I had a carbide bit but it broke the second I tried to use it on some 440c. I guess I have a little play in my drill press.
 
I've had good luck with the carbide tipped masonry bits on high carbon blades. Just understand that they'll likely leave you with a slightly larger hole than 1/4", not that it will be a big deal for tang holes.
 
If you find yourself up in the Mooresville, NC area you can drop by and drill them on a big mill. I have a 1/4" carbide drill you could borrow for it.
 
Nathan the Machinist said:
If you find yourself up in the Mooresville, NC area you can drop by and drill them on a big mill. I have a 1/4" carbide drill you could borrow for it.
Click to expand...

I have a buddy that's going to take them to work and give it a go. If he cant do it I will let you know. Im in Charlotte everyday through Thursday. Thanks for the offer Nathan. I wouldn't mind checking out your outfit anyway!
 
I have had good luck spot annealing hardened blade handles before. Steps should be taken as mentioned above to keep the rest of the blade from heating up too much. The way I did it was at a higher speed with an old masonry bit. The spot would get bright red and it seemed that when it was at that temperature the metal was pretty soft. You could just go all the way through twitch the mounted bit but it might not give you a clean hole. Once spot annealed I switched back to a regular bit and was able to easily drill through the spot. I don't know what type of stainless steel that was though so I am not sure if the spot annealing would work on all steels.

It worked on this 5 bladed cleaver.
katsuknife4.jpg
 
On a stainless steel, like CPM-154, the steel will re-harden every time it cools back down from red. It might be at a softer temper, but it is still too hard to drill with a regular bit.
 
I just use carbide bits for the stainless blades when I need another hole. They usually work real well.
Frank
 
For hardened steel, I really like 140 deg notched point straight flute carbide drills. They're more rigid than the spiral flute, they drill more concentric and accurate, and spot their own holes. Which is a big plus when you're dealing with hardened steel that you can't easily center-punch, let alone run a spotting drill on.


Bite the bullet, buy one in the size you need, and have the peace of mind that you're using the right tool for the job and not likely to screw anything up. I drill holes in 62 RC stainless all the time with them down to 0.045"


Remember, small diameter carbide needs to run fast, not slow as you're always told for steel, and no violent "pecking".

Ebay is a good source, just search for "straight flute carbide drill" in size X. Most domestic carbide is good quality. I can highly recommend the "Best Carbide" brand, you'll likely see in search results. I buy most of my small diameter end mills from them. Super sharp, I like their AlTin coated tooling.

Here's a link to a 1/4" drill for $18+shipping: http://www.ebay.com/itm/1-4-2500-SO...ILL-BIT-NEW-/301570893105?hash=item463706a531
 
Ok, you can't post something like this, without the story behind it.

Is there a link somewhere on BF about it?

eyeeatingfish said:
I have had good luck spot annealing hardened blade handles before. Steps should be taken as mentioned above to keep the rest of the blade from heating up too much. The way I did it was at a higher speed with an old masonry bit. The spot would get bright red and it seemed that when it was at that temperature the metal was pretty soft. You could just go all the way through twitch the mounted bit but it might not give you a clean hole. Once spot annealed I switched back to a regular bit and was able to easily drill through the spot. I don't know what type of stainless steel that was though so I am not sure if the spot annealing would work on all steels.

It worked on this 5 bladed cleaver.
katsuknife4.jpg
Click to expand...
 
javand said:
For hardened steel, I really like 140 deg notched point straight flute carbide drills. They're more rigid than the spiral flute, they drill more concentric and accurate, and spot their own holes. Which is a big plus when you're dealing with hardened steel that you can't easily center-punch, let alone run a spotting drill on.


Bite the bullet, buy one in the size you need, and have the peace of mind that you're using the right tool for the job and not likely to screw anything up. I drill holes in 62 RC stainless all the time with them down to 0.045"


Remember, small diameter carbide needs to run fast, not slow as you're always told for steel, and no violent "pecking".

Ebay is a good source, just search for "straight flute carbide drill" in size X. Most domestic carbide is good quality. I can highly recommend the "Best Carbide" brand, you'll likely see in search results. I buy most of my small diameter end mills from them. Super sharp, I like their AlTin coated tooling.

Here's a link to a 1/4" drill for $18+shipping: http://www.ebay.com/itm/1-4-2500-SO...ILL-BIT-NEW-/301570893105?hash=item463706a531
Click to expand...

Hmmm? Ive always run the carbide at about 220 r or whatever the slowest on the drill is, With a drop of cutting oil every 20 seconds or so.
You say fast works better with carbide on hardened steel?

What speed do you run them at?
 
I run 1/16 carbide drills at like 4500 rpm, without coolant, and gentle pecking to clear chips if the hole is deep enough to warrant.

AlTin coated carbide is designed to be run dry, and carbide doesn't appreciate intermittent cooling, it's better for it to run hot.
 
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