Drawing back a throwing knife after harden???

DanGraves

DanGraves

Knifemaker / Craftsman / Service Provider
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Mar 5, 2006
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I have a client that has ordered a Damascus throwing knife. I made it out of 1084 and 15n20. I have not hardened it yet and would like to know the best temperature to draw back after harden for a throwing knife. I really want it where it wont break. Will have an edge just not sharp. Any Ideas what it should be? Thanks
 
Hi Dan! I still have great memories of the time Rupert brought me to your shop about a year and a half ago. I made some nice knives with the blackwood you gave me. Thanks!

I believe you could simply temper the knife down to about HRC 50 or even less. I would be surprised if someone would throw one of your knives when he could just as well be throwing a $10 knife though.

IMHO, throwing knives are kind of disposable. You can only straighten them so many times, and they can get lost easily.
 
Dan, I know next to nothing about throwing knives so take all this with a grain of salt but I'm thinking that I would draw it back to just before the edge would roll on the brass rod test. I think those steels at that hardness would be tough enough for throwing but still hold a fairly decent edge. But I may be totally wrong. LOL
 
From what I've read... and I could be wrong, but I don't think they're supposed to have an edge at all, only a tip. I would think mid to low 50's.
 
I don't have the documents on this computer, but from the top of my head, I would temper 1084/15N20 at 600F to get a low 50's hardness.
 
Hey Dan. Damascus throwing knife - Wow! What's the overall length and the thickness at balance point?

I expect a decent 3X step-down normalization (unify and refine grain size) is a key to any forged thrower, but especially after the time your stock billet spent at welding temps. Fine-grained steel is definitely tougher all else being equal.

Are you planning on a full quench in your regular oil brand? If so, I'm betting you will have to approach 650F X 1hr to hit HRc 48 to 52. I suppose the debate is about the appropriate hardness/geometry combo.

I agree with Grizz's last comment FWIW, but the customer is always right (well almost always;)). I got a look at a set of 3-month-old SOG throwers last week hanging in the van of my HVAC guy. Way past "well used" and approaching hammered dog cr@p. Maybe your customer has more experience or better judgement. Suppose you could toss in a few cheapo Chinese throwers to delay the inevitable...

Let's catch up soon!

Andy
 
Andy, I don't think a Damascus throwing knife is any crazier than a Damascus handle broach. By the way, I never got to see a picture of the one you made for Dan.
 
bladsmth said:
I don't have the documents on this computer, but from the top of my head, I would temper 1084/15N20 at 600F to get a low 50's hardness.
Click to expand...

Isn't that temp at the peak of blue-brittle? I would say a spring temper at 700°
 
The temperature is what I am hunting for. I dont have a Rockwell tester and it will not have enough of an edge to do a roll test. It will be about 1/4 inch think and 15 inches long. That is what the client wants but I think it will probably end up being about .200. I want it to be tough and springy. I think I may put a small piece of the same steel in treat it the same way the test the heck out of it. Any one out there made one that has held up?
 
Yes, I have my charts out now, and Rc50 would be about 750°F for 1084. Rc55 would be 650°. At 600° you are in the Rc 57-58 range. 15N20 has a higher range, with Rc55-56 at 700°.

So, 700°F to 725°F sounds like a good temper for a throwing knife in a 1084/15N20 mix.
 
I have a couple of notes from over the years each basically saying the TME range is roughly 500 to 640F for low-alloy carbon steels. That's why I suggested 650F. Have had some 1084fg tool blanks that were just freaky tough - all dead now - cooked at 675F X 2hr. Some sword guys would call BS on those specs. As I understand it there are apparently several forms of tempering-induced embrittlement happening across at least two distinct temp ranges. Dunno???

700F x 2hr sounds really smart for the application.

Jason, better yet why don't you just come to the next hammer in and you can trash Dan's set on some scrap; he says they're about ready for a tune up anyway. Its how they work, not what they look like (still working on saying that with a straight face:D).
 
Stacy and Andy, sounds like it will be 713 degrees for 2 hrs. Then I will test the extra piece I put in there with it.
Andy, what the hell makes you think I would loan my broaches to anybody???? And yes you need to get your a@#%% up here and tune these baby's up. :>).
 
Thanks Karl. Copied that chart and in my files. Will print out and post in my shop.
 
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