I called Paul Bos: Diff. Heat Treat on ATS-34

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Sep 23, 1999
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Hello! I called Paul tonight and asked him the recipe. Here goes:

1 cup of sugar, 3 eggs, 1 and a half cups of cocoa, ... oh wait, that was Mrs. Bos' recipe! Never mind that one.

O.K., here's the recipe for steel:

A local knife maker guy and Paul worked on this together. The knife maker guy (herein referred to as 'dude') made knives up to 14" long using this method, and then made some swords, so it should work for your ATS-34 project.

So, here's what you do. Take some 3/4" water pipe and grind in a 1/4" split down one side. You wil place your knife in the slpit edge down. On one ond of the pipe, braze on a water hose bib. On the other end of the pipe, attach a plug (braze, weld, I don't know. Jut make it stick) and drill 4 3/16" holes. Finally, lay the rig so that when you turn on the water, it flows downhill.

The idea is that you turn on the water so that it cools the edge. The plug with the holes in it is to restrict the water flow. You want to adjust the water until it is flowing up 1/2" on the blade.

Take 2 rose buds (Oxy/acetylene torches, excuse the spelling) and heat both sides of the spine.

This method works for ATS-34, 154-CM and BG-42.

Heat the back of the blade until it turns just over a dull red color in dark light. if the blade turns bright red, you have gone too far. When parts of the blade start to turn dull red, you are at about 1000 degrees. When the whoel blade is a dull red, youa re at about 1300 degrees. 1300 degrees is where you are aiming for. You have to go over 1000 degrees to get the spine to drop below 59-58 degrees.

As soon as you get that even dull red, turn off the heat and let the water run until your blade is cool.

If you get things just right, the spine will Rockwell at about 50.

Originally, Paul and Dude did 10 blades and the first ones didn't get below 55 Rockwell. But with practice they consistently got down to 48-50 Rockwell.

The Dude has since made some swords and diff. heat treated them and they'll whack through 4" saplings with no damage to the edge at all. Pretty cool!

If you want to do this with 440-C, you need to back down on the themperature a bit. You want it at 1100-1150 degrees, not quite at a red color in a dimly lit room.

Paul said that with practice you can get it just right.

I had a fun time talking with Paul about heat treating and his history. He's been doing heat treating since the time when he was IN highschool! He knows his stuff! unfortunately I caught him when he was gettign ready to turn in for the night. Paul was very pleasant to talk to. I will definitely call him up again!

Good luck to all fo you knuts who are going to try this
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"Come What May..."
 
Crayola, Thats very interesting. Thanks for posting it. That is just what the big ATS Work knifes need I think. Does it show the temper line like straight carbon steel does? Bruce B
 
you know Bruce, that is one question I didn't ask! Next phone call I guess.

Diff. Heat treated ATS-34 would make a kick butt blade. And if it gets a temper line? COOL!!!

I'm not sure if it would get such a lien though. Clay treatments or edge quenching is quite different from this set-up. Try and see, or call Paul I guess!

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"Come What May..."
 
Boy am I gonna show my ignorance on this one but, if you temper the spine to the point where it becomes more flexible than the edge, won't there more stress put on the harder edge and it be more likely to break??


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Take care!! Michael
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Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!
I currently don't have a web site but am working on one.
Buzzards gotta eat, same as worms!!!
 
Differential Stainless, pretty cool. My understanding is that a differential temper on a large blade will allow the blade to take more shock without breaking in two. The harder edge may chip but the knife won't be in two. The stress on the edge is the same. You can repair a damaged edge, if ain't two bad but a knife in two, well...
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sing
AKTI #A000356
 
There is no stress on the edge. The only thing that has changed is now it has a soft back and spring temper somewhere in between the two. I made a fillet knife that came out of the niquid nitrogen bent a bit. I had to bend it to at lest 45 degrees to straighten it. It was at 58-59 rc hardness. ATS is very nice steel for flexing anyway.
 
Very cool! And, way over my head, hehe. I have decided to send my first blade to Paul Bos for heat treat, does he have a web site?

Anyone know about where his prices run? (9" OAL, 4 1/4 blade ATS-34)

Thanks,
Troy
 

Rest assured, Paul is DA MAN when it comes to knowing about heat treating. He has been doing HT all of his life, and sounds very dedicated to knife makers.

Give Paul a call and ask him his prices on HT.


(Edited to eliminate incorrect pricing information!)
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"Come What May..."


[This message has been edited by Crayola (edited 05-04-2001).]
 
Paul charges $60 for up to 20 blades. After that I am pretty sure its just $3 per. And that includes cryo.

R.W.Clark
 
Paul did this on a couple of my ATS-34 swords and it worked very well. Both blades were about 21" long and could easily be bent about 3" by hand. The thing to remember there is that the edge is at about Rc57-58 and is also bending 3". ATS-34/154CM is only brittle if it is not properly heat treated.

You could just make out the differential temper in the intensity of the brushed lines in the finish.

Paul did say it wasn't something he wanted to do very often, however.

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Jerry Hossom
www.hossom.com
The New Tom & Jerry Show
 
Troy : I will do single blades of stainless for $12.00 each plus shipping & handling, Am not doing the Diff. H. T., I just dont have the time.Paul.
 
Thanks, Paul! I wasn't thinking differential heat treat on this one, just normal.

The Diff. heat treating question was my thinking it worked like carbon steels, to which the answer was a resounding "NO! Heat treating more complicated than you think, get someone you can trust to do it for you."

Hehe, glad I figured that out before I screwed the thing up by trying it myself.

Paul, sending off an email to you, thanks again. :)
 
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