Trad Gang
Main Boards => Hunting Knives and Crafters => Topic started by: Wyostikbo on January 06, 2008, 08:27:00 PM
-
I have a concrete saw blade I want to make a knife out of. I tried one and it came out fine, I just don't think the steel is hard enough. I can drill through it without heating it up red hot and letting it slowly cool down.
Can somebody tell me the procedure for hardening steel.
Thanks.
Brent
-
Can't you get it red hot then put it in water.
-
Can't help you unless I know what kind of steel it is. Old saws work best because most of them are L6 tool steel. Alot of the newer saws and files are case hardened and don't make good knives.
Most high carbon steel is heat treated by heating it to 1650 degrees (cherry red) and quenched into oil heated to 120-140 degrees. That is the hardening process. Then the tempering process can be done in a kitchen oven. About 1 hour at 300 degrees. Chad
-
I'd have to guess that the steel in a concrete saw is not good knife steel. Same for all blades that use diamond or carbide for the cutting action.
-
I have some concrete saw blades, but I've noticed they dont rust much. I have concluded they may be or very close to being some kind of Stainless. It's very hard to temper for someone new to working steel. I would search around and find an old sawmill blade (L-6) and I can help you with that. It's a high carbon steel and will be more likely to make you a good knife. Lin
-
How big of blade you looking to make?<><
-
I think you guys are right in thinking the steel isn't good enough for a knife blade. I was just hoping I could harden it somehow.
I'm not looking to build anything big, maybe 7"-8" OAL.
I don't have access to any old saw blades but would be willing to buy one if there are any available.
Thanks.
Brent
-
if i had your address i could send you some. loyd
-
gotta be careful with that one gene. oil hardening steels can rip apart violently if quenched in water...
aren't most concrete saws diamond blades? if so they are relying on the hardness of the diamond powder to cut the conrete, not the steel...they are probably using a lower carbon steel for the blade part so it can stand the temperatures generated in the cutting??? just a guess.
you could do 2 tests...one like Lin said to see if its stainless...get gun blue and see if it blues...if it wipes right off its stainless and would require highly technical hardening/tempering process....if it stains with the bluing do a 'quench test'....cut a small piece off, heat it to red, then quench in oil (used motor oil, transmission fluid, veggie oil) I use canola oil, then clamp one end in a vise and whack it with hammer (donning proper safety attire, goggles gloves, apron, etc)..if it bends over it ain't hard. repeat the heat and this time quench in water....again if it bends it aint hard...no good.
if it snaps or shatters then its pretty hard...probably hard enough to make a knife.
-
I often use concrete cutting saws for the steel in my blades. I only use the saws that are around 2 foot across or bigger and I test the steel before I make anything worth keeping.
It is true that when the saw is doing it's original job it is the diamonds that are doing the cutting, but the saw must be strong enough to be able to take abuse AND stay in one piece while doing some serious RPM, this requires steel of pretty good quality. It might or might not be L6 used these days (it was used in times past for saw blades WITH integral cutting teeth) but either way it is hardening and tempering fine and the tempering recipe (and the knives performance) is close enough to L6 for it to make no difference.
Some blades made with concrete saws
(http://img.photobucket.com/albums/v243/jindydiver/earlyjunebatch2.jpg)
And one didn't like the quench
(http://img.photobucket.com/albums/v243/jindydiver/heattreatdisaster2.jpg)
The test to see how good it will perform
(http://img.photobucket.com/albums/v243/jindydiver/heattreatdisaster3.jpg)
(http://img.photobucket.com/albums/v243/jindydiver/heattreatdisaster4.jpg)
I had this blade over at near 80 degrees before it snapped and the handle sprung back a heap.
I don't ever use those dinky little 12 or 18 inch saws. I had no luck with them earlier and don't believe that the steel is good enough to waste time on.
-
My blade isn't 2 ft. But I think I will try the tests on a small piece and see what comes of it.
Sounds like I may need to find an old saw blade that's made out of real steel.
Thanks.
Brent
-
Not wanting to hijack the thread but I had a question. I have been making a few knives out of 10" table saw blades. They sharpen to a really good edge but I haven't had a chance to give them some use yet to see how well the edge will hold up. I read on another site about doing a brass rod test on the blade to check the hardness. Exactly what it this test? I'm guessing you try cutting or peeling the brass with the edge to see if it will chip or hold it's sharpness. Just wondering. Thanks.
Aaron
-
The Brass Rod Test (as it appeared in BLADE Magazine) by Wayne Goddard
The brass rod test was demonstrated to me in 1959 by an old blacksmith who made knives in the 1930s. Here is my version of the brass rod test which is simple test of heat treating to help determine that a blade will hold up in normal use.
Clamp a 1/4-inch-diameter brass rod horizontally in a vise with the top half above the jaws. Or glue it to a piece of hardwood. Lay the knife edge on the brass rod at the same angle used for sharpening (about 15 degrees). Have a good light source behind the vise so that you can see the deflection caused by the rod on the edge. Apply enough pressure so that you can see the edge deflect. (When tested on a scale, the pressure works out to 35-40 lbs.) If the edge chips out with moderate pressure on the rod, the edge will most likely chip out in use. If the edge stays bent over in the deflected area, it will bend in use and be too soft to hold an edge. The edge of a superior blade will deflect on the rod and spring back straight.
The test is intended for knives in the hunting knife class. Thin filet knives or thick camp knives will not respond to the test in the same way. The blade that is too hard will chip out in normal use, too soft and the edge will bend. The brass rod test can quickly determine if the blade has a good balance of flexible strength and hardness sufficient to hold an edge.
The brass rod test as I present it is not intended to replace a hardness test to determine that a blade was fully hardened. It only applies to blades that have been tempered. I have worked out my version using it on blades made of alloy and carbon steel types that backyard heat treating methods are adequate for. The brass rod test is only a comparison test to determine what is in my opinion a hardness that will hold up in normal use. I started using is about thirty years ago and still think it is the best non field-use test I've found for testing the suitability of a blade steel and heat treatment for a working knife.
-
Robtattoo, thanks for the quick response. So much good information here.
Aaron
-
re: brass rod test
if you don't have a brass rod handy a croc stick (ceramic rod) will work in a pinch. I like to do it a little differently too...instead of clamping it in a vise, I like to lay the rod on a sturdy table, place the blade edge against it at the appropriate angle and roll the edge (and rod) from choil to point...with enough pressure to actually see the edge deflect, and if it stays bent or warps at all its too soft, if it chips from the pressure...its too hard.
-
Brent i have a small care package made up for you , will try to get it in the mail tomorrow. loyd
-
The other good test for temper and edge holding sharpness is to see how many critters it skins without sharpening. This past Bear Quest, I threw about 10 different knives out and let the guys do what they wanted with them. It was incredible for me to see which designs worked best. Plus I did different tempering to see how well the edge held up. Got more info than any other testing so far...Doc
-
its on its way have fun, i want to see pics. loyd
-
Originally posted by tippit:
The other good test for temper and edge holding sharpness is to see how many critters it skins without sharpening. This past Bear Quest, I threw about 10 different knives out and let the guys do what they wanted with them. It was incredible for me to see which designs worked best. Plus I did different tempering to see how well the edge held up. Got more info than any other testing so far...Doc
I do a similar thing. One knife out of each batch gets given to my hunting buddy (who is notoriously hard on knives) and he tests it for function and performance. He is suitably brutal on me if I have made a dud
(http://img.photobucket.com/albums/v243/jindydiver/2007/mesospiker2.jpg)
-
I’m a frequent visitor to Trad Gang, as well as a professional knifemaker. Please allow me to assist in flattening out your learning curve here a little bit on getting your steel hard.
It can be a rather daunting task to get things all identified and controlled, but with just the simplest of actions, you can make a serviceable blade.
First and foremost, you need to identify your steel type/classification. Different steel types contain different alloys and these effect the manner in which they will harden. Different temperatures and quenching media all come into play.
Here’s a basic procedure:
Heat up a piece of steel until it becomes non-magnetic and then cool quickly.
Simple, right?
At first glance.
One good thing is that all ferrous steel becomes non-magnetic at 1413 degrees. That is easily demonstrated! Heat up a piece of steel until a magnet no longer sticks to it!
That proves that atomically you have changed the condition of the steel. It is at that point that, depending on the steel type, you need to drop it’s temperature in only a few seconds to below 900 degrees.
Some need to make this drop in as little as 1 second, and others take as long as 4 seconds.
Too slow - no cigar.
Too fast - no cigar.
That is where the proper quench oil comes into play.
Firstly, canola oil is for cooking French fries.
Quenching oil is for cooling steel.
It is basically mineral oil, BUT! with special additives that absorb heat at a particular rate for the steel at hand. That is why there are different quenching oils for different steels, due to the rate of cooling necessary for that steel’s alloy content.
Have a known steel, but use the wrong oil, and you will fail.
W1 steel – quench in Water! O1 steel – quench in oil! A2 steel – air quench! And so on.
Then there are different oils for different steels speeds.
Here’s what happens – you bring a piece of steel up to that non-magnetic temperature and you have changed the steels condition. If you just let it cool slowly, it RETURNS to the same condition it was in when you started – soft.
You can watch it go black, and with your magnet, check as it slowly returns to a magnetic state.
But, if you heat it up to that non-magnetic condition and then quench it quickly in the appropriate quench media and cool it to below 1000 degrees at the proper rate for THAT steel, you “freeze” the steel atoms in a condition that is hard, because you stopped it from RETURNING to the condition it WANTED to go to – SOFT.
However, you have paid a price. It is really hard, but also brittle. It is not happy here.
So, we “temper” the steel to slightly soften and relieve the hardening stresses that have been induced in the alloy matrix.
Somewhere above I saw the temp of 1650 degrees or something like that. That’s way to high for the simple steels you will normally be using. A high temp for a chromium steel is 1525.
And, the mentioned tempering temp of 300 is way to low. More like 350 – 425 depending on how hard it got and the steel type.
Search you area for a gallon or two of medium speed quenching oil. A gallon can be ordered from Brownelle’s. I guess in a pinch, you would use Vet grade mineral oil from your local feed store. It will work for medium speed steels, but not the high carbon tool steels.
See, some oils remove the heat too slowly for “fast” steels. The steel will actually return to that “soft” state faster than a medium speed oil can remove the heat! Get it?
Some tool steels require the heat to be removed from 1500 degrees or so down to under 1000 degrees in less that 1 second!
Medium speed oils like mineral oil just won’t handle it.
That’s why so many new makers get frustrated by having good quality steel, but are quenching in the wrong media and can’t seem to get the steel hard! The oil is too slow.
Some guys quench in water and the blade cracks! The water is too fast!
Or, they don’t get that steel up to non-magnetic and change the steels condition. In that case, it won’t harden even if you have the correct quench media.
Lot of stuff to consider.
Know your steel.
Have the right quench media.
Get it up just past non-magnetic.
Hold it at the temp as long as you can without going too high.
Quench in the right stuff.
Do your research!
Good luck, guys.
-
Hey Karl! Good to see you here. I heard you were a tradbow hunter. Too bad you cant come to Curtis' place with us.
Guys, Better listen up, cause this guy is one of the best.
Lin
-
Hey, Lin. I'm sorry I can't make it as well. Breaks my heart! I mean that.
I'm knee deep in sweat right now getting ready for my JS applicant knives. Does this mean I'm not gonna sleep for the next 4 months?
Anyway, I read that thread and just had to jump in, give a few basics to start and leave out all the fancy words.
Correct any errors! I make plenty of 'em!
About 1/2 the time I figure if you follow me you'll end up lost anyway.
You guys have fun without me.
I'll expect a full report.
-
Karl, Thanks for posting. Most of us are just hunters trying to make some sharp tools. Nice to have some pros stop by...tippit
-
Hey loyd been making any knives?<><
-
Hey Karl, thanks for the help, like Doc says, it's great getting some Pros on here. First Lin now you, cool! Several of us have been tinkering for years and turn out some decent stuff but there's always plenty to learn! :thumbsup: :thumbsup:
-
Karl,
when you are dealing with old saw blades and files, or even new saw blades and files, how do you figure out what type of steel it is?
-
go up 6 posts , he tells you how. loyd
-
I don't use any un-known steel.
As a professional knifemaker, it's of the utmost importance to me that my heat treating processes are specific to the steel I'm using so I am confident I will achieve the desired results.
Even the non-pro should just use known steel.
You file and grind and beat and bend and cut and drill and sand and sand and sand some more.
Now, you go to heat treat and not know what steel you have? All that work for nothing?
Buying a bar of known steel and using the industry standard method of heat treating is always the simplest way to go.
-
Well said Karl! An 18" length of 1/8"x2" 01 steel really isn't expensive. It's very easy to work & has a HT cycle that is a cinch to do. It makes excellent knives too! :)
-
Thanks for pointing that out, Loyd, but he didn't actually answer my question in that post. He does answers it two posts up that he just doesn't use an unknown steel.
The reason I ask is I am wanting to make my first knife and I will have two old 26" sawmill blades and a new one, plus some new nicholson files. Are there any markings or engravings on the blades that will give you an idea of the type of steel?
If not I guess I just need to experiment and see how hard or soft after heating to demagnetization and cooling.
By the way, thanks for your posts, Karl!
-
Old sawmill blades are most likely L6. How old are they? If your aiming at a knife to use that will hold a decent edge for hunting them sawmill blades will work great. I love sawmill blades for knives ... they have soul and character.<><
-
Sticshooter,
I have not received them yet. Bought two old ones and a new one off an auction website. Beginning to wonder if i am gonna receive them. When I get them I will take pics and post them. Maybe ya'll can help me figure out if they are L6 or not.
-
Hooked, the only way you'll ever know for certain that you've got L6 steel is if you BUY L6 steel. There are so many different steel compositions out there, you'll never, ever tell by looking what you've got.
If you're serious about making a good, working blade, buy some good quality steel to start with. For price you've paid for the 3 mystery saw-blades, I reckon you could've bought a good amount of 01. A known & trusted carbon steel.
-
http://gbrannon.bizhat.com/old.htm#folders lots of info here. loyd
-
Depending on how serious you are about using this steel, and it appears you are, I just a post on another site where you can get it an analysis for 40 bucks or something like that.
If you want that info, I can probably dig it up for you.
-
Very true only way to be 100% sure is to buy L6 steel. Most old sawmill blades were L6. If they made big sawmill blade to cut timber I just figure it must be some good steel. Now I am talking old blades not new blades like table saws. Kinda hard to believe they would make a sawmill blade out of junk steel. I am no pro but I have some knives here that I made from sawmill blade steel. I chopped all kinds of branchs and hacked on some frozen osage and they are still more then sharp enough to do what they are intended to do.JMHO<><
-
The only thing with using 'junkyard steels' is you have to be willing to sacrifice a knife or two.
If you can harden a test piece like was described earlier, go ahead and make a knife. After you quench it, draw the temper back at around 350 degrees, put an edge on it and abuse the knife. Hack away on a 2x4 and check the edge - if it chipped the blade is still too hard and brittle, if it bent it's too soft. The first problem is easily fixed by tempering at a higher temp (say 400) the latter problem means the knife needs to be normalized, rehardened and tempered at a lower temp.
If there are no problems with the blade after chopping on a 2x4 do the brass rod test Rob described somewhere. On a properly tempered knife the edge will not chip, crack or be permanently deformed. There are some exceptions to that test however (you can get away with a harder edge on a small knife that won't see hard use - like a small caper or a neck knife).
The majority of common steels you'll come across that'll make a decent knife can be quenched in oil - most any oil actually. I've been using 1095 which has a pretty 'hard nose' for a simple steel (you need to drop it's temp quick for it to harden) and if you look at its spec sheet, it's listed as a water-hardening steel. I'm quenching in corn oil and I *know* it's working well. Used motor oil didn't seem to work as well - it still hardened, but the quenched steel didn't seem quite as hard. Water worked extremely well, but if you (being ME) overheated the steel even slightly there was a good chance the blade would crack.
Though I mostly use known steels, I have to agree with Frank. Using reclaimed steels (resurrected :) ) appeals to my, uh, frugal nature and the blades do have something special about them.
Here's a plug for Frank's knives:
I have one of his sawmill knives. The first thing I did with it was put a scary sharp edge on it and hack most of the way through a doug fir 2x4. It still shaved hair after and there was no damage to the edge. The brass rod didn't phase it either. Would it have passed the ABS JS test - well, no, but it certainly wouldn't be due to edge retention. :D
-
I meant to add that where the proper quenching oils that kbaknife mentioned earlier really come into play is in industry where they are heat treating a large mass of steel.
For a relatively thin blade made out of the simple steels (10xx series) and simpler alloys (5160, L6, O1 etc) you can use, and have confidence in, a quenching medium you find at your local grocery store :)
Even the manufacturers of many of the (good) high carbon damascus steels these days are recommending quenching in a veggie oil.
-
Have been watching this thread for a few days. I've got most of my work area set up this weekend, bandsaw, drill press, belt/disc sander, vise, etc set up.
Jeremy has graciously sent me some kiln brick. Propane torch purchased.
I am looking at getting some old saw blades to try. But, after looking at this thread not sure what to do.
So the next question is where does a person get the L6 steel or other types of steel to do this.
Nick
-
Jantz Supply (http://jantzsupply.com/)
Texas Knife (http://www.texasknife.com/)
Texas Knife has O1, 1080, 1095 and 5160.
Jantz has 1095 and O1
All will make a good knife.
-
http://img.photobucket.com/albums/v259/loydlippert/bowieelkhorn.jpg here is an old saw blade- some rust. loyd
-
http://img.photobucket.com/albums/v259/loydlippert/bigkniferago.jpg or this
-
http://img.photobucket.com/albums/v259/loydlippert/bestfilepic.jpg old rasp