Squaring Grind Shoulders, and a HT Question

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me2

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Oct 11, 2003
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I just finished grinding my first blade, a small wharncliffe, out of O1. One of the shoulders got off line and I'm trying to figure out how to even them up. Also, what is the easiest way to heat treat this steel? I was going to use a propane and fire brick forge, but havent bought them yet. I also thought of just using a torch, since the edge seems to heat up quite quickly. I'm not going for super quality yet, just want to harden the edge if possible. Thanks for the help.
 
I won't speak on the shoulders since I'm not the best at that myself yet. For hardening you could use just the torch if the blade is small enough. You need to be able to get at least the entire edge up tp temp, the entire blade if you want a full harden. You'll need a magnet, a file, and some oil. Almost any oil works though alot of people will reccomend their favorite. Heat the blade until the edge or whole blade is non-magnetic, heat it a little bit more, dunk in oil as fast as possible once you remove the heat. Take your file and scrape it across the edge, if it bites then you need to do it again and change something. Maybe quench it faster, or let it soak at temp a little longer or shorter. If the file skates across the edge without biting, then it's good to go and time to move on to tempering. I'm not sure if you know how that works since you didn't ask, so I'll assume you do unless you do ask.
 
Thanks about the heating. The blade is only 2" long, and I may have ground it too thin at the edge, but we'll see. Ed Fowler used a torch to treat his blades, and some of them are >5". Does he use a heat trap of some type? My ideal setup would be the One Brick Forge from $50 Knife Shop, by Wayne Goddard, with a Mapp gas heating torch. My limit for blade length right now is about 4 inches, enough for some utility fixed blades and a friction folder or 2. I'm only planning on hardening the edge. I have access to a hardness tester, so the file wont really be neccesary. The tempering instructions are on the package from the steel, and I think I can do it in the oven. Does O1 benefit from a double temper? I thought I read that some steels it doesnt really seem to help, but I dont remember specifically.
 
All steel benefits from a double temper (except for the exceptions of course). When you quench, some of the austenite is left over and tempering helps it transform to martinsite. Unfortunately this new martinsite hasn't been tempered since it's new, so you need to temper again to get the new stuff.
 
When plunge lines do not match, the easiest way is to look at the edge, which side is longer?, turn your belt around so the side that ground the long part is now on the short side and you should be able to match them up.

This happens because both sides of the belt (edges) are not always exactly the same, the solution is to use the same side to equal it up.

A torch is my heat source of choice, I practiced on mild steel for a long time to get it the way I wanted it. The torch permitts a lot of freedom when you seek to do it your way.

Use the proper oil at the correct temperature, a search will reveal my thoughts on oil etc.

Good Luck
 
Ed do you prefer a plain propane torch, or the Oxy torch?

I have 2 propane torches already, but if I didn't have them, I would move directly to a 1/2 or 3/4 burner, unless I was doing only a piece or two as I have in the past, it's cheaper for me to set up off the BBQ propane, and I have a hybrid burner that should do everything from 1 brick forges to 3/4" burner of trad. construction. Not quite there yet, won't know until I get back to the shop in September whether this new small burner will be the ideal small to medium setup, and I could be wrong.
 
I just purchased a kukri from atlanta cutlery. It is thier new military issue knife . It seens like a well made knife though it was very very dull on arrival. Could anyone tell me what steel is used in this Kukri, and do you consider it a good knife ? Is an HI Kukri a better blade and lastly what sharpening techniqes do you use?
Thank you for any help you can give.
 
Protatical: I have never used a propane torch to harden blades, I use an oxy-acet set up and a Victor 3-w tip on larger blades, smaller tips on small stuff. A soft flame, 2x keeps from burning the steel or hot spots. I believe that the propane torch would work well.

The main ingredient is practice and tincture of time. Always check with a magnet, always!! Once nonmagnetic get to the oil immediately. Checking steel cooling from non magnetic, as indicated on the way up, can cool below the hardening temp and still remain non magnetic. On the way up the magnet is an accurate predictor.

If I were hardening my first blade, I would grind one simialr out of any scrap steel and practice hardening it many times before I went to the real blade. On a small blade, I would slowly heat the spine, playing the flame to the middle letting the edge come to non magnetic, being thinnner should get there before the spine, then quench.

Be sure to polish out all scratches above 220 before hardening. Small scratches can encourage faults in the finshed blade that extend below the depth of the scratch.

Differential hardening is an art, you will never cease to learn her secrets. Once you have found her secrets, you will never wish to let her go. Like many of man's dreams, getting there is what makes the goal memorable.
 
Ok, lunch break. Ed, I was thinking the same thing myself. The edge is really thin, so I was going to heat the side and let the edge heat up from there. I have a tendency to do things right the first time, but the second time gets screwed up. I figure I have one time to harden the blade, then I'll have to practice to figure out how I did it. As an example, I ground the first side exactly how I wanted, but the second side was off. How large a blade can be hardened with a torch using the methods in your book? I'm still limited to about 4 inches, due to my grinder set up, but I'm curious. Thanks for all the advice everyone.
 
Me2:
I have hardened blades up to 10 inches with my torch. I have found that slowly bringing the blade up to critical is beneficial, heat uniformly - one side then the other keeping the heat uniform. I love to watch and nurture the magic moment as critical temp is achieved.
 
I don't think a propane torch could do a knife that long though since it doesn't get as hot as the oxy/acet does.
 
Years ago, (the dark ages) it was widely believed that it was impossible to make Damascus steel with a propane forge. I remember using an O2 boost on my forge. Then I started to learn how to adjust the gas - air mixture and steel started welding up for me. We normally think of the little propane outfits, but it can be used to attain high heats for large volums.

Wayne Goddard related an incident when several men hardened a 200 pound anvil using propane weed burners, fire brick and the McKensey river for a quench tank.

If you don't believe that propane can get hot watch the glass blowers, they really know how to get the most out of propane and air.
 
Oh, I definately know propane can get hot enough, my GF blows glass. Just not one little torch without any sort of shell. I've had a hard enough time getting a shorter blade up to heat with a torch in open air.
 
Well, it appears I need more practice at grinding than anything else. I took of too much with the 80 grit belt, and when I tried to polish down to a 220, the edge got sharp and then kinda jagged. The knife has a slightly different shape now, but it should be fine. I did manage to even up the shoulders a little, but I had to use a file. The plunge grinds go a little into the spine as well, but not enough to hurt my feelings. I think I'm gonna go with the propane and one brick forge/furnace. I ran out of daylight, but I'll propbably get some brick and the torch tomorrow, final polish and harden on Thursday. Thanks for all the help. BTW, is it just me, or are wharnecliffe blades easier to grind than ones with a belly?
 
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