Could laser cutting O1 somehow harden it?

Y

yessahmassah

Joined
Sep 22, 2015
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A friend of my grandfathers has a computer controlled laser cutter, so I just got him to cut my blanks out for me, and Im having a real hard time filing it down on my bevel jig. It almost feels like the files are just skating off. Ive made a little progress, and when I say a little, I mean a little.
 
This stuff is definitely hardened. I filed for like 15 minutes and all it did was scratch the surface. I thought maybe the file was worn out, so I used a fresh one. Same thing. I sent an email to the people I got it from to see if it was shipped in the hardened state. Im planning on annealing it.
 
That's to bad sometime if I don't drill my holes before I flatten any steel it takes a lot more effort to drill.. Work hardened or case hardened .
 
Marko3 said:
That's to bad sometime if I don't drill my holes before I flatten any steel it takes a lot more effort to drill.. Work hardened or case hardened .
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Yea. Definitely an extra pain I should have to do, but oh well. Im going to guess the metal was hardened from where I got it. I don't really see how laser cutting could harden it.
Atleast I hope its not the laser cutting. Its SO much easier than using an angle grinder or a hack saw. And they come out with almost no profiling needed.

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Yes, there is a heat affected zone next to the cut that will harden. Heat blades to 1250f for 4 hours and you're good to go.

Hoss
 
DevinT said:
Yes, there is a heat affected zone next to the cut that will harden. Heat blades to 1250f for 4 hours and you're good to go.

Hoss
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Wouldn't it be a very very thin section? Like something I could get through pretty quickly with a grinder? Think I could just take a little off with my belt sander then be able to file? I don't mind having to anneal it, but if I can avoid it, then Ill save a few hours.

And I thought you had to heat it to 1450* then let it cool very slowly to anneal O1? No way my paint can forge will be able to stay that hot that long. Especially if I have to do 4 blanks. Haha
 
It's a sub critical anneal. Grind through the heat affected zone and you'll be good to go.

Hoss
 
Yes, absolutely, laser will harden the steel in the vicinity of the cut, usually 0.010" to 0.020" wide.

Any kind of softening heat treat (temper, stress relief, or anneal) will improve it.

My knives have a laser-cut lanyard hole. It is easier to chamfer that hole at final hardness (50 RC) than it is when the knives are fresh off the laser cutter. Even non martensitic stainless such as 304 will have a rock hard heat-affected zone from laser cutting.
 
P.Brewster said:
Yes, absolutely, laser will harden the steel in the vicinity of the cut, usually 0.010" to 0.020" wide.

Any kind of softening heat treat (temper, stress relief, or anneal) will improve it.

My knives have a laser-cut lanyard hole. It is easier to chamfer that hole at final hardness (50 RC) than it is when the knives are fresh off the laser cutter. Even non martensitic stainless such as 304 will have a rock hard heat-affected zone from laser cutting.
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Thanks. Ive got them tempering now, and Ill see how that does it. Crazy how hard it is. I wore out a file pretty quickly. It was a cheap file, but still. I wish I could test the hardness to see just how hard it is.

Nathan the Machinist said:
This is why we use waterjet for roughing out blanks
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If I had access to that, Id definitely use it. But if the tempering works and softens them up enough, then Ill probably continue to get them laser cut.
 
Yeah, O1 will air harden a good bit if cooled fast enough.
Even 1084 will do it off a laser, let alone the regular air-hardening steels. The thin bits near the laser cool fast enough due to convection into the rest of the piece (I think) to simulate air or oil-quenching of the whole piece.
 
check out laser hardening for tool steels, apparently its a new cool kid in the hardening methodologies Block
 
I find the HAZ on knife steels is about .10"wide. This is because that area was taken to above 1400F during the cutting. I just grind it off, but if it was a batch of blades, I would do the sub-critical anneal Devin recommended.

Typo - that was suposed to be .010"
 
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I saw a guy on youtube testing for hardened parts of an axe head with a hand held automatic centre punch the gold type everybody normally has, on the head of the axe a large hole was left, but on the axe edge it did not leave a mark at all as that part gets hardened.

see if you can make a mark on the unseen handle part of your knife blanks, if it leaves no make then it`s hardened.
 
Stacy E. Apelt - Bladesmith said:
I find the HAZ on knife steels is about .10"wide. This is because that area was taken to above 1400F during the cutting. I just grind it off, but if it was a batch of blades, I would do the sub-critical anneal Devin recommended.
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That would be extremely poor cutting conditions for laser. When I do it it's never more than .010" and generally closer to .005".
 
kuraki said:
That would be extremely poor cutting conditions for laser. When I do it it's never more than .010" and generally closer to .005".
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I can vouch for this. He cut a bunch of blades for me and thy have very little HAZ.
 
kuraki said:
What did you eventually end up doing for all the holes JTknives JTknives ?
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I used a carbide bur in a trim router and blasted right through the tabs and HAZ. Then wrapped A300 gator around a spindle and finished it. I used the harbor fright router and I am HIGHLY disappointed in it. Speed was fine but there collet and concentricity is terrible. But I had to get it done. DO NOT BUY one from harbor fright. You could see the bur wobble. I ended up shiming the collet with paper and used a dial indicator to tap it in. It worked ok and convinced me to buy a good brand. Been swimming in knives lately so I have not had a chance to research routers further to find a good one.

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