knives from leaf springs

A.McPherson

A.McPherson

Knifemaker / Craftsman / Service Provider
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Jan 27, 2012
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Well folks, after thoroughly hijacking someone else's thread, I decided to start my own! I raised the question if using an old leaf spring for blades is a good idea. Most folks advised me to forget it and just buy some stock and start there. I got the idea from another member to just try to harden a sample and see if it breaks easily.
I'm pleased to announce that it works! Wooo! Pretty awesome huh? Well I think it is! Yes I know, there is still the micro fractures to deal with, as well as the sheer size of the material(its .25 inches thick). But it gives me hope. I made a pair of knives one for my girlfriend and her Dad already, so I'm really glad to find out that the heat treatment that I did on them might actually have worked!
I'll post a pic on here once I figure it out!
 
Glad it worked for you.

The issues are:
1) Unknown steel...it could be 9260 or any of a dozen other alloys, but it is unlikely to be 5160.
2) Former life trail.....The thousands to millions of flexes the spring took may have induced micro-fractures or other structural defects.
3) Defects in the steel... The steel used for leaf springs is not necessarily the highest grade steel. It often has inclusions and other alloy defects.
4) Size.....The leaves come in sizes from about 1/4" to over 1/2". This requires heavy reduction.
5) Shape....The spring is curved, and well set in that shape. This requires full annealing and straightening. Just sticking it in a fire pit and leaving it overnight is not a good way to anneal it.

All this can be avoided by using a known steel.....1084 being the best candidate for a first knife.
 
bladsmth said:
Glad it worked for you.

The issues are:
1) Unknown steel...it could be 9260 or any of a dozen other alloys, but it is unlikely to be 5160.
2) Former life trail.....The thousands to millions of flexes the spring took may have induced micro-fractures or other structural defects.
3) Defects in the steel... The steel used for leaf springs is not necessarily the highest grade steel. It often has inclusions and other alloy defects.
4) Size.....The leaves come in sizes from about 1/4" to over 1/2". This requires heavy reduction.
5) Shape....The spring is curved, and well set in that shape. This requires full annealing and straightening. Just sticking it in a fire pit and leaving it overnight is not a good way to anneal it.

All this can be avoided by using a known steel.....1084 being the best candidate for a first knife.
Click to expand...


Yes use a known steel, old springs can be full of micro cracks as Stacy said, so why even waste the time, 1084,1084 1084, oh did I mention 1084?
Cheap
Known Steel
Now that you know the steel, you can heat treat it properly,
Easy to work
Time spent will be rewarded
End product has potential for being fantastic!
 
Why waste the time and energy? I thought about that one for a while and came up with the following answer. Mostly cause I'm really to stubborn for my own good. Rest assured that I will be buying some 1084 and making some knives the non cheap-'ol-bastard way. In fact I have some on the way from NJSB now, but for some reason I get a lot of satisfaction making something out of what most would view as trash! I know, I know! I'm digging myself a hole that I'm just going to be throwing time and money into... I know!

here's a link to the knife I made from my girlfriend and her dad. alas there's only one of them, but they are twins! I swear!

http://www.flickr.com/photos/40620963@N02/8572422248/

The handle is made of bone and walnut.

for those who have worked with bone before, how do you finish it so that it is smooth? I sanded it and buffed it, but it is slightly dimpled and has black streaks in it where the buffing compound got jamed into the pores in the bone. I tried alcohol and acetone to get it out but had no luck, any input?
 
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Try mineral spirits, or toulene, but I doubt that you will get all of it out. With time and use, that would probably have happened anyway.
 
Bit of an old thread I know

I'm not very experienced at knife making but I do like leaf springs for heavy use knives. I made two "hunting/survival" type knives from leaf springs of roughly the same dimensions, one for my buddy and one for myself. Mine is 7mm thick and my buddy's is 5mm thick. They are good tools. I get mine hair shaving sharp with no problem and it keeps its edge relatively well. I enjoy using it mainly to butcher chicken and other meat. Chopping through bones and cutting through cartilage with that weighty knife is dead easy! I've chopped wood with it but it has a 4.5" blade so it would be better to use the correct tool anyway like a heavy machete or axe. I think leaf springs would make good, tough, useable knives. Sure the steel might be unknown and might not hold the best edge, but its fun making knives out of them

Make a knife from one. If it comes out a dud, well then so what? No big deal. But how awesome will it be if it comes out great? Knowing that it used to be scrap

That's my opinion
 
I don't know the sources for steel in South Africa, but spring shops and machine shops usually carry new 5160.
I understand that in some parts of the world you just have to use what is available. If possible get the newest springs you can find. The longer they have been flexed, the more internal damage is done.

In the USA, ....brand new, perfect condition 5160 from Aldo in 6.5mmX50mmX1.25m is 240 SA Rand ( $26.50 US). You could get three monster 400mm choppers from that, and would only have about 80 SA Rand each in it ($8.25 US).
 
i have read alot that katanas and other swords are made from 5160 steel as well as 1095. but that the spring steel gives the swords nice flex. some of the most amazing swords i have seen (in person) are Dawson swords (and their knives too!)

http://www.dawsonknives.com/dawson-swords.html

almost all of their swords are made from 5160. although i totally get that the leaf springs could have micro cracks or other damage to them.
 
Flex is determined by thickness more than steel type or HT.
while years ago most leaf springs were 5160 or 9260 today they may be made of variations of those or other alloys !
 
Dear H20oni
on the bone super glue it on the last stage on the finale grind at 600 that way you can buff it
 
Zombie,
I can't speak for all the other sword makers, but 1095 and 5160 aren't the steels I make katana from....and not the steel most I know use. 1060-1070 is a much better choice. 5160 will work, but a hamon is not really possible. While possible, yaki-ire on a 36" long katana in 1095 is not a pleasant thought.
The flex on a sword or knife is related to the thickness of the blade, the length, and the geometry of the cross section. It isn't a factor of steel type or hardness.

As mete said, "leaf spring" and 5160 are not synonymous. I would never forge a katana from a mystery steel...it would just add a really bad ingredient to an already complex recipe.
 
Wow, h20oni. Your spring steel knife looks awesome. To be honest, I used to make a knife off of a scrap spring, but it's well heat treated and was able to chop and butcher big leftover live oak and meat with it. It's a little sad to say farewell to it as I sell it sooner or later, but I really want to buy Aldo's steel somehow.
 
I started with scrap steel, but quickly moved on to known steels. I know many scrap steels are perfectly fine for making a knife, but to make a great knife, not a "fine" knife you need to heat treat it properly. If you don't know what the steel is, how do you decide the temp, soak time, and quenching medium? That is a lot of guessing.
 
I had a buddy of mine who was showing me a very cool knife someone made for him out of some kind of truck leaf spring, I said hey you wont me to check the Rockwell hardness, checked it with my tester ( yep its a nice bench model that's been checked with 3 hardness test blocks, its dead on ) and it came out to 42 Rockwell ........ unknown steel is just that unknown....but there have been many makers that have used unknown steels to make very good blades, I guess its like rolling the dice, at least one will get experience with working the steel even if you can't get it as hard as you would like........
 
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