Making a German chip carving knife
I quite like German chip carving knives like the one shown here. I bought this one at a wood show, and have never gone out of my way to mail order more. So I thought I'd try to make a knife like this one out of an old saw blade. This one is not even carbide tipped. It was in a circular saw that I bought at a yard sale.
The blade was made of hardened steel, which is harder to work. So I softened it by heating it red hot in the wood stove. I then dumped the red hot pieces into the ash bucket to let them cool very slowly (ash is a good insulator).
Then it occurred to me - what if this steel is actually high speed steel instead of high carbon steel? So I did a spark test on it. I'm sure it's carbon steel, though possibly with not the highest carbon content. At any rate, if it was suitable for cutting in the form of a saw blade, it should be suitable for cutting in the form of a knife too.
A word of caution:
After that, I heated just the blade part of the knife red hot with a propane torch and quenched it in water. The rapid cooling from red hot causes the crystalline structure of the steel to change to get it hard again, whereas a slow cool will cause it to be soft.
Hardening steel like this can cause it to be so hard that it's brittle. I made another crude knife blade and hardened it the same way, then tried to bend it. I was able to bend it nearly 90 degrees before it snapped, so I figured, this steel isn't too hard for a knife, and I didn't temper it. Tempering the hardness is done by heating the steel to a specific temperature (not red hot) then letting it cool slowly. Basically, like softening it, but not all the way.
Mind you, even a soft steel can be sharpened to a very fine edge and it will pass these tests. The big question really is, how long will it keep its edge? Time will tell.
I put the blade in my table saw (the homemade one) and cut a bit off the edge of some wood.
I don't have any dust collection on that sander, so I set it up in front of an air filter. A box fan on the other side of that filter pulls air through it.
Brass pins would have been much more suitable, but I didn't have any handy.
Having had success with this one, made another blade for another knife. This one turned out better than the first, except I made the mistake of cutting the angle on the end of it the wrong way. The point on the right needs to be facing up, not down for it to fit in a blade kerf. So this one is junk. It's less work to make another blade than try to fix this one.
The blade in my first knife had a slight bit of play in the handle. I later made another knife blade and handle. This time I offset the holes in the handle slightly to pull the tang into the wood more, sort of like a drawbored mortise and tenon joint. I also drilled a few extra holes and roughened up the side of the knife, then filled the slot in the handle with epoxy before inserting the blade. I figure the roughening and the extra holes will help the glue hold the blade.
There are a lot of videos on making big fancy knives on YouTube. Daggers, swords, machetes, bush craft knives, etc. But how much do you use a dagger or a machete on a daily basis? How much "bush craft" do you do? What makes this different is that it's a knife I will use often. So this will be a good way to check it's durability.
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