Hardening knife blades

backpackin

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I'm lookin for someone who hardens and tempers knife blades professionally in and around the Salt Lake City area of Utah. I have made a couple of knife blades and I'm guessing they need to be hardened to hold a nice edge. I used a cement saw cutting blade to make the knives, from what I have read, this metal is called L6, have any of you guys out there made and used knife blades out of this material? How did the edge hold up?
 
L-6 is a high carbon steel that is used a lot in saw blades. If heat treated right it will harden to around 60RC and will hold a very good edge. Only problem with it, is that it will rust or stain very easly if not cared for.

The hardening process is diffiernt from stainless steel. It will have to be heated to around 1500-1550 degrees and oil quenched. If it would have been a stainless steel, I would have have told you to send it to Texas knife supply and they would have heat treated it for you for under 10 bucks a blade. I do not think they do heat treating for high carbon steel such as L-6.

After hardening, it also has to be tempered at leaset once at a temp around 400 degrees for 1-2 hours to get the desired hardness. After coming out of the oil quench it will be as hard as a file and too brittle for knife use.

You may need to check your phone directory for knife makers that forged their blades and they should be able to harden and temper the knife for you if they are willing to take on your blades.

RELH
 
Hey thanks RELH I appreciate the help, I'll keep looking for knife makers in the area. What kind of an edge would it hold without going through the hardening and tempering? If I could gut a deer or elk a couple times a year I would be happy.
 
RELH is right on. L6 will rust but over time the blade will take on a nice patina if you take care of them.

There is a wide range of acceptable additions of alloying elements for L6 depending on who made it. If it is on the higher side in manganese and has additions of moly, it will air harden. If is is lower in manganese and higher in nickel without the addition of moly, then it is oil hardening. I would save any scrap pieces of the saw blade for whoever does the heat treating so they can work up a heat treatment schedule with the scraps and not on your finished knife blades.

L6 will hold a good edge and is really tough when properly heat treated. The resulting microstructure is made up of tempered martensite and bainite. Martensite is responsible for the hardness and ability to hold an edge. Bainite is responsible for the toughness and impact resistance of the blade. Bainite is the microstructure found in things like lawn mower blades.

Hope they turn out well for you and be sure and post up some pics of the finished blades. A field evaluation would also be in order.
 
It will need to be heat treated for any good edge retention. You used a cement saw to profile the blades out. By doing that you heated the metal up to over 400 degrees near the edges you cut. I would not be surprised if you saw some of the edges turn blue where you made the cuts. That blue color means the steel reached a temp of over 600 degrees and that soften the steel to a RC that will not hold a decent edge.

RELH
 
To the best of my recollection, typical saw blade steel has a rockwell hardness of 42-44. I custom ordered some round saws once with rockwell of 50-52. I was hoping that they would stay more flat from abuse in an edger. They did hold up better, but when they got bent it took some pretty hard blows to straighten them out. The saw company also warned that they could break and fly into pieces (more brittle). They were also a pain to roll tension into, so we eventually abandoned the idea.

Eel
 
Somebody get a hold of GERBER!

I've got a GERBER Folding Lockblade that nobody can Sharpen!

I think they over done it on this knife?

You know anything on this RELH?

I have experimented & found if you go to a 30 degree angle you can sharpen it a little bit!




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Hot Dog,Hot Damn,I love this Ameri-can
 
Bobcat, awhile back a guy brought me a fixed blade Buck knife. He said nobody could sharpen it. I took it home and tried. He was right. I couldn't begin to put an edge on it. That sucker is hard!

I took it to work and put it on the power diamond wheel we use to sharpen carbide. Now he can shave with it. I don't know the angle because I just free handed it.

Wish I had your Gerber here.

The Mexicans at work saw me do it once and now they all bring their knives in to sharpen. I let them do it and they always burn the temper out because they let it get hot. I would esplain but they don't speak much english.:)

Eel
 
STTM, I too have a Gerber that is tough to sharpen. Finally gave up and use it for a work knife. Eel, send me some info in a PM. I would like this knife with a razor edge. Worked it on many stones for hours and damn, it holds the edge for quite a long time but you wear out a good stone trying to sharpen the bastage!!
 
LAST EDITED ON Mar-29-12 AT 12:35PM (MST)[p]You guys with hard to sharpen knives. If you have a powered belt sander it is easy if you follow some simple rules. You will need several new sanding belts. 100 grit, 220 grit, 400, 600-800 grit.
Start with 100 grit to establish a 20 degree angle on both side until you get a burr edge. Use light pressure to prevent overheating and becareful at the tip that you do not remove too much metal due to heavy pressure.

Work you way up to the 600 or 800 grit and sand both sides until you get that burr edge. You should be able to see and feel the burr edge. On my knives I use 6 different belts all the way to a 1200 grit before I polish the burr off with a well used crotus belt loaded with Jackson white polish compound for a edge that is as sharp as a straight razor, but stronger due to the convex edge I get from a slack belt on the grinder.

Use a strip of leather with polishing compound to remove the burr edge and you should be able to shave with it. I believe there is several videos on using a belt sander to sharpen on Youtube that you can watch. Just be careful and watch one that the guy appears to know what he is doing. using fresh belts and light pressure should not produce excessive heat on the blade.

Your big problem will be keeping a consistant angle while free hand grinding. So go slow and remove equal amounts of metal from both sides of the blade.

If you are scared to risk your knife, send it to Eel and he will fix you up for a fee that I will get a kickback on.

RELH

P.S. If your knife has a semi-sharp edge to it, start with the 220 grit belt instead of the 100 grit. I start with 100 grit due to it being a new knife without any angle and 30 thousand thick.

After you get it sharp and it starts to dull down the line, you should be able to touch it up by starting with a 400 or 600 grit and this way you are not removing too much metal everytime you resharpen.
 
yes I can as I use the same 2X48 belts on my grinder used for sharpening knives. Go to web site Supergrit.com and you will find those belts. They have been the most reasonable in price I have found in the past few years. They may even have a wool or felt belt in that size that can be used with the polishing compound to remove the burr and put that razor edge on your knives.

Be careful about letting your wife and friends know about this as you will be kept busy sharpening their kitchen knives. But again that would be good practice before you start on your good hunting knives.

RELH
 
Got me a new Buck Lock Blade 2 days ago & broke the Tip off it the first day I had it!




[font color=red size=redsize=18"face"]SHOW THEM TO ME![/font]
If You Love Your Country,SHOW THEM TO ME!




Hot Dog,Hot Damn,I love this Ameri-can
 
>Somebody get a hold of GERBER!
>
>
>I've got a GERBER Folding Lockblade
>that nobody can Sharpen!
>


Turn it over bess...


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Gonna send it to you Snort!

Maybe you can sharpen it on a Bear Rib?:D




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If You Love Your Country,SHOW THEM TO ME!




Hot Dog,Hot Damn,I love this Ameri-can
 
Dingo, They aren't finished yet, and still need a lot of work but I thought I'd post a couple of pics so you could see them. This first knife I wanted a rugged hunting look, so I used a doupble eye guard deer antler base which actually makes a perfect spot to put the thumb when I grab hold of it. Plus I never have had a gut hook before so I thought I would make my own.
8418knife_4.jpg


9681knife_3.jpg


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Then this little guy is supposed to be a skinning knife.
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8627knife_6.jpg
 
Hey backpackin, those are turning out great. That antler looks like it fits your hand really well. It is rewarding to make gear that fits you and your needs. Thanks for sharing the pics.
 

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