Throwing Knife Construction

[dwaterfield]

When friends find out I'm making knives, I get a lot of interesting questions. A recent one was whether I could make a throwing knife. I said "maybe, I need to do some research!"

I am by no means an expert on throwing knives. I've thrown from time to time and taught my sons how to do it. I do know there are some important aspects to the design, such as a handle that easily slides out of your hand during the throw. There are also debates about whether it should be balanced or blade heavy. One thing that surprised me is that I can't so far find a good reference on basics such as metallurgy.

There seem to be several schools of thought. Some talk about using unhardened steel to reduce brittleness. Various sites online are selling knives made out of hardened O1, though. I've even seen everything from mild steel to damascus. There doesn't seem to be much consistency.

To me, a throwing knife would have to be all about function. What will throw well and stick while putting up with the abuse they take?

I'm hoping someone can point me to a good book or other source on the subject.

Thanks!
Doug

 

[DevinT]

When friends find out I'm making knives, I get a lot of interesting questions. A recent one was whether I could make a throwing knife. I said "maybe, I need to do some research!"

I am by no means an expert on throwing knives. I've thrown from time to time and taught my sons how to do it. I do know there are some important aspects to the design, such as a handle that easily slides out of your hand during the throw. There are also debates about whether it should be balanced or blade heavy. One thing that surprised me is that I can't so far find a good reference on basics such as metallurgy.

There seem to be several schools of thought. Some talk about using unhardened steel to reduce brittleness. Various sites online are selling knives made out of hardened O1, though. I've even seen everything from mild steel to damascus. There doesn't seem to be much consistency.

To me, a throwing knife would have to be all about function. What will throw well and stick while putting up with the abuse they take?

I'm hoping someone can point me to a good book or other source on the subject.

Thanks!
Doug

Knife steel nerds toughness testing.

Book: knife engineering also

Hoss

 

[Richard338]

You can buy sets of throwers of various quality quite cheaply. In order to be interesting to make, I would want it fully functional as a knife, and not obviously a thrower. Looking at Larrin's toughness charts, Z-tuff, 3V, and 8670 look like good candidates. Z-tuff and 3V have a little corrosion resistance and edge retention so I'd start there.

ETA Hoss posted while I was typing

 

[Richard338]

Made my first pair of throwing knives

they're not quite finished, but they're at a point where I can finally test them. 8mm thick A2 with epoxied kevlar handle wrap

www.bladeforums.com

 

[Lorien]

to my way of thinking, it might make sense to start out with mild steel and get your design dialed in first. That material works fine for a throwing knife and takes out the energy and time intensive hardening and tempering process so that you can spend your time making more iterations and get the important design aspects nailed down first.

I don't think the material matters all that much, since you'd likely want to temper your knives down into the mid 50s which will make a lot of the regular considerations for knives moot. Edge holding and edge stability isn't really an important consideration. As for stainlessness, you can etch your knives in ferric chloride and wax them or use paint to seal them up.

design-wise, a knife made for no spin throwing might be substantially different than one made for regular throwing.

 

[velegski]

It depends on what customers want. Back yard, rendezvous, or knife throwing league's. Weight and length could be considerations , particularly for league throwers. Generally i shoot for 14-16 ozs.for adults. Handles optional, just tell don't make them part of any guarantee as they get busted up fast. Personally I use mild steel or 5160. The 5160 is usually heat treated as it could be used as a camp knife.
An internet search for rendezvous or competition knives will give you an idea of styles for each
As Lorien stated, no spins are a different bird so I stay away from them.

 

[Forest Ninja]

.

 

[dwaterfield]

Knife steel nerds toughness testing.

Book: knife engineering also

Hoss

Thanks Hoss. I had seen the Knife Nerds site once previously. There is a lot to digest there!
I think a friend of mine has that Knife Engineering book; I'll have to see if he'll let me borrow it.

Made my first pair of throwing knives

they're not quite finished, but they're at a point where I can finally test them. 8mm thick A2 with epoxied kevlar handle wrap

www.bladeforums.com

to my way of thinking, it might make sense to start out with mild steel and get your design dialed in first. That material works fine for a throwing knife and takes out the energy and time intensive hardening and tempering process so that you can spend your time making more iterations and get the important design aspects nailed down first.

I don't think the material matters all that much, since you'd likely want to temper your knives down into the mid 50s which will make a lot of the regular considerations for knives moot. Edge holding and edge stability isn't really an important consideration. As for stainlessness, you can etch your knives in ferric chloride and wax them or use paint to seal them up.

design-wise, a knife made for no spin throwing might be substantially different than one made for regular throwing.

I think the post Richard quoted was from you! I was thinking I should reach out to you, so thanks for responding. Mild steel for testing designs is a great idea. In your thread you mentioned using A2 for that set of knives. How has that worked out for you?

I was not thinking about no-spin. I've not attempted throwing that way in years!

It depends on what customers want. Back yard, rendezvous, or knife throwing league's. Weight and length could be considerations , particularly for league throwers. Generally i shoot for 14-16 ozs.for adults. Handles optional, just tell don't make them part of any guarantee as they get busted up fast. Personally I use mild steel or 5160. The 5160 is usually heat treated as it could be used as a camp knife.
An internet search for rendezvous or competition knives will give you an idea of styles for each
As Lorien stated, no spins are a different bird so I stay away from them.

Thanks for the notes. With mild steel are there any issues with toughness? I had seen 5160 mentioned a couple times. I haven't worked with it much but from what I've read it makes sense to me.

You mentioned handles. I've seen a lot with paracord but they seem to fray and fall apart. I wonder if leather wrapping would make sense.

 

[Hengelo_77]

Have a look here

Throwing Knives & Knife Throwing

Hosted by Bobby Branton, of The American Knife Throwers Alliance. All aspects of throwing discussed!

www.bladeforums.com

 

[A.McPherson]

You mentioned handles. I've seen a lot with paracord but they seem to fray and fall apart. I wonder if leather wrapping would make sense.

I've seen some with leather "scales" held on with rivets. Seemed to work pretty well. Not that they looked good or anything, but they made the grip wider...

 

[Alex Topfer]

I think V velegski is on the right track: what exactly are they doing with this knife? Sporting competition, decoration they might throw at something in the back yard once or twice?
Throwing knife is a bit like fighting knife; a simple name covers a wide range of possible use cases.
5160 is cheap, tough, and can hold an edge, so a good option if you can't get a useful spec

When this happened to me my solution was to let them use the workshop until they lost interest in the project

 

[velegski]

Handles are nice for occadional throwers. But for the serious they tend to get beat up, chewed up and removed as accuracy improves. FYI, keep a file handy and check for burrs after every throw, even a small burr will rip a chunk out of your hand.
If handles are a must then riveted leather over wood. Wood Knicks, splinters and splits.

 

[Lorien]

Thanks Hoss. I had seen the Knife Nerds site once previously. There is a lot to digest there!
I think a friend of mine has that Knife Engineering book; I'll have to see if he'll let me borrow it.




I think the post Richard quoted was from you! I was thinking I should reach out to you, so thanks for responding. Mild steel for testing designs is a great idea. In your thread you mentioned using A2 for that set of knives. How has that worked out for you?

I was not thinking about no-spin. I've not attempted throwing that way in years!



Thanks for the notes. With mild steel are there any issues with toughness? I had seen 5160 mentioned a couple times. I haven't worked with it much but from what I've read it makes sense to me.

You mentioned handles. I've seen a lot with paracord but they seem to fray and fall apart. I wonder if leather wrapping would make sense.

yup that was me, and for sure feel free to pm me any time. I don't have a ton of experience to share but I'm happy to share what I know and also what I think I know, (hence two cents).
I used A2 for mine because I had a couple drops left over from a previous project that needed to be turned into something. I tempered them down a bit and etched and waxed them for corrosion resistance. They were heavy beasts that hit hard, and they also have edges which can actually cut things. They belong to RayseM now, and he's been throwing them so maybe he'll chime in if he feels so inclined.
I don't think that the material is all that critical, not nearly so much as the heat treatment.

 

[JoeBusic]

Mine are in 420HC@57HRC. No holes, rounded edges and a semi thick tip.
Soft will break it faster. Repeated wiggle and bending will crack it easily. Soft is prone to dents when hit into a hard surface or object.
Hard will keep it's form even with abuse. Hard will endure way more vibrations.
Avoid carbides and round the edges to avoid stress risers.
Design wise, do what you like. There are handle throws, blade throws, no spin and combinations. Best is to make the center of gravity in the middle unless a specific throw style is wanted.

 

[dwaterfield]

I think V velegski is on the right track: what exactly are they doing with this knife? Sporting competition, decoration they might throw at something in the back yard once or twice?
Throwing knife is a bit like fighting knife; a simple name covers a wide range of possible use cases.
5160 is cheap, tough, and can hold an edge, so a good option if you can't get a useful spec

When this happened to me my solution was to let them use the workshop until they lost interest in the project

I've thought it might be faster to teach them how to make their own, so I like the idea of having them use the workshop!

I think my friend has an interest in competition but for now it's just something they like to do occasionally. Their question got me wondering about it though.

Handles are nice for occadional throwers. But for the serious they tend to get beat up, chewed up and removed as accuracy improves. FYI, keep a file handy and check for burrs after every throw, even a small burr will rip a chunk out of your hand.
If handles are a must then riveted leather over wood. Wood Knicks, splinters and splits.

Yeah that's one of my biggest concern. I'm a Scout leader so I've seen the abuse throwing axes go through. I assume it's only worse for knives. Leather over wood is a good thought, should be light but put up with a fair amount of abuse.

yup that was me, and for sure feel free to pm me any time. I don't have a ton of experience to share but I'm happy to share what I know and also what I think I know, (hence two cents).
I used A2 for mine because I had a couple drops left over from a previous project that needed to be turned into something. I tempered them down a bit and etched and waxed them for corrosion resistance. They were heavy beasts that hit hard, and they also have edges which can actually cut things. They belong to RayseM now, and he's been throwing them so maybe he'll chime in if he feels so inclined.
I don't think that the material is all that critical, not nearly so much as the heat treatment.

Thanks Lorien. I like multitaskers so I would generally lean towards something that could be used as a camp knife also, but I wasn't sure what people who buy such knives are looking for.

Mine are in 420HC@57HRC. No holes, rounded edges and a semi thick tip.
Soft will break it faster. Repeated wiggle and bending will crack it easily. Soft is prone to dents when hit into a hard surface or object.
Hard will keep it's form even with abuse. Hard will endure way more vibrations.
Avoid carbides and round the edges to avoid stress risers.
Design wise, do what you like. There are handle throws, blade throws, no spin and combinations. Best is to make the center of gravity in the middle unless a specific throw style is wanted.

Thanks Joe. I see a lot with holes or slots, I assume that is to try and adjust the balance? Seems odd to introduce stress points into something being thrown around though.

It sounds like the consensus is a steel that is under 60 for hardness, and the steel itself doesn't need to be anything exotic. It also seems like something thicker than what I'd normally make for a general use knife is a good idea. I just watched an Alec Steele video where he made some very heavy and thick throwing knives. From what I've read they're probably a lot heavier than people would typically throw but the results were pretty impressive.

Thanks for all the thoughts and references, everyone. I have a lot of reading to do!