Sawblade sleuthing; makes good blades?

[MarkFromUtah]

Hello fellow bladesmiths. I'm not really a smith technically--I do stock removal knifemaking, but here's a question I need help with. I have a large supply of circular sawblades to use as material for my knives. I realize that all saws are made of different alloys, but all of them tend to be carbon steel at some level. I have an especially large supply of worn out concrete-cutting diamond tip blades (approximately 29" diameter and 3/16" thick). I also have lumber mill blades and others of unknown origin. I am equipped with a 2000 degree oven, so I can do my own heat treating. First question: do the concrete blades make good knives? I've asked around a lot, and sniffed the web to find everything I can about them. One manufacturer told me they use 4130 steel. Knifemaker Ed Caffrey told me they're either 4130 or 4140. That seems to be a fairly low carbon content (maybe .3 to .4 percent), but my tests have turned out pretty good. I've tried normalizing and then triple quenching in water for best results. It makes an extremely tough knife. I haven't done extensive edge testing, but I know that I can bend a finished and tempered blade to 45 degrees (with a lot of effort) and it springs back to true. Newly quenched test pieces break at about a 60 degree bend with a clean grain. I've heard that this steel is best for thick bowies, hatchets or throwers, but I refuse to give up on making general using knives from it--mainly because I have TONS of it. Will multiple quench and temper cycles refine the grain? Am I wasting my time? The other wood-cutting sawblades I have are much harder, and only need a single oil quench and tempering to make a great knife. I think they're probably L6. I'm really curious to understand how much you can evoke the qualities you want from steel with proper heat treatment. I appreciate any and all comments!

Also... is there a place I can send test strips of this metal for analysis to tell me exactly what the alloy is?

 

[Jason Magruder]

www.admiralsteel.com
Buy new steel and know what you have.

 

[MarkFromUtah]

Wow... that's helpful. Any knifemakers out there who are experimenters like me, and understand the true spirit of finding out what makes things tick? I don't do this for a living. David Boye and Wayne Goddard and many others who I respect started out by using recycled materials!

 

[paintfool]

I can't really help you out with this but I do back your experiments 100%...
the way I look at it, if you can find out what it is then why not use it?
one thing I have been told is try to find a makers mark and contact the original supplier, even try asking who it is you got it from if they remember who they got it from and track it down that way.

 

[Stacy E. Apelt - Bladesmith]

About three thermal cycles is all the grain refinement you can do with any increase in grain refinement.More than that and the decarburization will be too much,probably.The 4130 will make a very tough blade,but will need resharpening more often (hence- choppers and such). The L-6 will make a better blade for cutting purpouses.I am also a believer in buying known steel from Admiral or Crucible. BUT,if you have an unlimited supply of the same type of steel,AND,you have tested it thoroughly - WHY NOT USE IT.My complaint is junk steel from unknown sources.

 

[Todd Robbins]

MarkFromUtah

From my personal experience, used circular sawblades that had carbide tips were pretty low in carbon, and the diamond tips are probably the same. If you bring it to nonmagnetic and quench in warm water, it should break like glass when you hit it with a hammer or try to bend it. Anything less is not suitable for knife making, for my uses. You might try looking for Tai Goo's Super Quench recipe that he uses on RR spikes, which seem to have about 40 pt.s of carbon. Tai hangs out in the Outpost on The Custom Knife Directory forums.

The saw blades that I have that don't have brazed-on tips are definitely high in carbon. Most people say L6, but I have never used any steel that I knew was L6, so I can't say for sure. They make great knives, though. Most are forged (at least the edge bevels), and are subject to several thermal cycles there. I normalize them three times, after annealling once. I bring them to nonmagnetic and quench them in 135+/- degree Crisco Shortening, three times. On the first knife blade out of any sawblade I do my first temper at 350 degrees, sharpen, do the brass rod test, and temper accordingly, for a total triple temper (or more, if it takes me that long to pass the brass rod test). Then I test, test, test, test, test, test, test (the first blade, anyway )

Todd

 

[oljoe]

Mark,
I used some concrete sawblade steel to make some blades. It worked well, but I tested it throughly. I did a little research on the sawblades and the only thing that I could find was that they may be 65Mn, a Chinese steel that is equivlent to 1066. This may or may not be the case with the saw blades that you have. Thats the trouble with using junk steel, you realy don't know for sure what you have. About the only way to trust what your using is to test each sawblade throughly. The manufacture may not even have used the same steel in each blade.

Anyway here is the sight.
http://www.scipress.com/0-87849-927-X/233.htm

Joe Foster

 

[peter nap]

First, welcome to the forum Mark. I'd like to begin by saying that there is a very diverse mix on this site including some of the finest knife makers/smiths in this country. There is a general feeling among most that in order to give the customer what he wants and needs, you must start with known quality and content......I agree with this to a large extent and support the makers that do not encourage frontier methods.

For myself, I am an experimenter but I do not try to tell people my knives are anything other than what they are. "Knives made from some unverified steel"

Now on to your question.

The blades will be made from a variety of steel. As already stated, the ones with carbide tips should be saved for idiot Frisbees.
The others should be heat treated until you find a HT package that works with that particular blade.

With the concrete blades, I've found that they can make good knives but I have to harden and temper by color until I find the heat range that works. Some have had to be tempered at 500 F to temper properly. I guess the put Krypyonite in those

If you can find out who makes or distributes them, call, they are generally helpful. The steel name they will give you is almost alway a proprietary steel but it will have properties close to some known type.

Good luck