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Timothy Artymko

Heat Treating Throwing knives

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I have been approached by a client asking about some throwing knives, and I am willing to make them, but I need to know the best hardness I should have on a knife like that. I am thinking something like 80CRV2 for the knives. What would be the beat way to go about heart treating/tempering these for the optimum strength as a throwing knife? I was thinking a 2 one hour temper cycles at 400 F, but I don't know if that would be enough.

 

Thanks!

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i had a order for a bunch and ended up in the 55 rockwell range .. i actually had to straighten a couple of them after hardening and tempering... it took a lot to het um straight they were tough...

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80crv2 would be perfect. Don't worry much about tempering throwing knives too soft, between 45RC and 55RC will work just fine. If it were me I'd probably temper at between 450F and 600F for at least six hours total, but seriously don't worry about it too much. ;)

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Good to know about the lower hardness range! I am just in the process of getting the best edge on knives right now, so I really needed outside experience to tell me what to do here. I figured they are probably going to never hold a real good edge, but at least they won't shatter... hopefully!

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I make them out of mild. I don't want them to shatter or spall chips off. It's not as if they are going to get used as cutting tools. If they bend, NP, just bang them straight again. In the end they are all going to get lost in the brush at some point.

 

Another option would be to leave them in an as forged state, normalized, no heat treat.

 

I am in the minority in this, I know, but I'd rather have them bend than chip or break.

 

Geoff

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Throwing knives aren't supposed to be sharp at all, so you really don't have to worry about edge retention. just aim for something that is really springy. I'd probably shoot for a plum color in the temper.

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I'm with Geoff. They're novelty items that will get lost, I wouldn't put much time into 'em. Mild will be fine, if they MUST be extra sturdy you can't do much better than that 80CrV2 in as-forged condition. If you do harden and temper go for a full spring temper, 575 degrees F or so.

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So use something like 1045 is what you guys are saying? And just harden it with a snap temper and call it quits? I really have no idea of this realm of knives, so I would love to get my head wrapped around this :)

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NO, not hardened with a snap temper! :excl: That way lies broken blades and possibly injured owners or bystanders. IF you harden it at all, temper the bejeezus out of it, properly. As-forged and normalized is fine.

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I didn't know 1045 could get that hard... I figured an oil quenched 1045 blade with a snap temper would be around 50 HRC... I stand corrected. Just out of curiosity, how easily will something as-forged and normalized be?

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It may be around 50HRC, but for 1045 that's hard enough to break, especially if the temper is not even, which is sort of the definition of a snap temper. Torch-tempered to a full blue three times would work okay, that's what I do for hawks and axes that need to be tough enough not to chip when they hit a nail. That's using 1084.

 

I'm assuming that last word is "bend," and it depends on the steel. 1045 will be about twice as easy to bend as 80CrV2. Alloys are much tougher than straight carbon steels, even though they all have pretty close to the same modulus of elasticity. The alloys will be harder to move and harder to make stay bent.

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If you want cost-effective use 1/4" mild steel. Chances are nobody will notice the difference for this application.

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Whatever's available and cheapest. These are going to be abused and lost, no point using good steel on them. Unless the customer insists and pays well for it, that is.

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Ok, so just some cheap-ass steel with an as-forged and normalized treatment? I am good with that as long as it will work decently :P Like i said, I ahve no experience in this realm other than my own tinkerings from a few years back when steel types and treatment were nothing to me xD

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This is one of the few times when rebar or RR spikes makes sense (to me at least) as a material. NO HEAT TREAT, at all, none. Forge them if you want to ( I have mine waterjet) and a quick grind to soften the edges. I also grind about a 45 degree bevel, which makes them look kinda knifey. The fact is mine will stick handle first about as well as point first, and I have even had them stick on the "guard" .

 

throwers 1.jpg

 

throwers 2.jpg

 

You can make a good throwing spike out of the big concrete nails, but 1/4 to 1/2 square or round mild steel is also a good choice. Grind or forge a point on each end, you could even do a hot twist to give a good grip. If you put more than about 10 minutes each into them, you've already over priced the market.

 

Now I'm thinking that it would be cool to do some RR spike throwers. A quick forge into a leaf blade, and a quick pass on the grinder, done. Maybe a twist handle. You'd probably need to get $25 a piece for them, but they would be sort of cool.

 

Geoff

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I have 30 throwing spikes and knives stuck in a target near my forge...all are Normalized not hardened!

I once made the mistake of hardening one forged from 5160 and giving it a fairly springy temper above 500f. First throw was minutely off of "perfect" and the wood target refused delivery. The knife rapidly became "return to sender" at nearly the same velocity I threw it!

Most of my early ones are mild steel spikes and leaf blade patterns I made for forge practice and I lean towards that for any I make for myself.

If a customer wants a "better" steel, that is fine, but I will never harden another throwing knife.

James

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So I'm not the only one! That is good to know.

 

I've got a great idea (well maybe not a great idea, but a fun one), RR spike throwing knives and one piece throwing hawks. For the hawk, draw the handle from shank, bend the head over and forge the blade from that. Darn, I don't think I have any RR spikes in the pile!

 

Geoff

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I have about as many spikes as I could wish for! I think I will try that throwing hawk idea! I think it would be awesome!

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