Knife from file/rasp help

T

trains are bad

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Jan 29, 2004
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My GF's dad gave me a worn out rasp, the double-ended kind that they use on horse hooves. It's pretty big and course.

He gave me an internet article that says that one can make a knife out of a file, it instructs one to heat it red hot and let it cool slowly to anneal it, then shape the knife by grinding.

I've always heard about making a knife from a file and always wanted to try it. I'd like to know if it's possible to get good results from this type of file (which was surely chosen just because it was worn out), and whether the methods are on the right track. Is it a pointless endeavor? Maybe you know of some articles? Some resources on this site?

I have an acetylene torch, one huge industrial angle grinder, a 4 inch angle grinder, and a 3" beltsander. What belts should I get?

Also, taking suggestions on blade shapes. Neo-tanto would probably be the cop-out for the newbie knifemaker.

I want to do this, because it seems like a sort of man-test from him to me, and I might need to talk to him soon about marrying his daughter. So help!
 
If the only reason you want to do this is to prove something to someone else, I hope that in doing so the the bug catches you and you choose to carry on for your own fulfilment!

I think most of the older, better quality files etc were made of good high carbon steel roughly equivalent to 1095. This is a good steel for knives so the reason for using files is more about materials than it is about finding a use for old scrap!.

Good luck

When you anneal it you should leave it in the furnace/ fire to cool down very slowly as the furnace/coals cool down.
 
Oh I've made and worked on knives myself anyway. I've just never used a file. I also don't have a forge, but I forgot to mention I have a bench grinder and a dremel too.
 
trains are bad said:
Oh I've made and worked on knives myself anyway. I've just never used a file. I also don't have a forge, but I forgot to mention I have a bench grinder and a dremel too.
Click to expand...

You can make a quicky forge using your acetylene torch. Get a refractory brick from a local supplier. Hollow out a hole through the length of it that is large enough to accept your file. If you need it larger, use more bricks to make a round opening in the center (basically half circles out of two bricks and then mate them together. In one of the bricks make a hole coming in from the side to put your acetylene torch tip through. This will hold the heat in very well. Heat the file up until it no longer draws a magnet, then stuff it down into a bucket of vermiculite. You can get vermiculite at your local garden center or a nursery. This will allow the file to slow cool and you'll have a very nice soft piece of steel to cut, grind, shape, etc.

When you're ready to harden it, put it back into your make shift forge. Bring it up to non-magnetic and then pull it out and let it cool in still air. This is called normalizing and will assure that you don't have any stresses in the now knife shaped object. When it is cool to the touch, put it back into your makeshift forge, once again bringing it back up to non-magnetic. Hold it at that temperature for about a minute, then quench it in preheated (120 degree) mineral oil or transmission fluid. As you progress, you'll want to use a good quenching oil that is made for hardening knives, but for now the mineral oil or transmission oil will do a good enough job to impress you future father in law. Run a file along the cutting edge to see if a file skates off of it. This will show you if you got the steel hard. By the way, if you use mineral oil it won't stink up the kitchen as badly as transmission fluid would.

As soon as the knifeshaped object has cooled in the quench to the point that you can touch it and you've proven to yourself that it is hard with your file test, put it into your kitchen oven at about 375 degrees F. for about an hour and a half, then let it air cool to room temperature. Run a file on it again to see if it is any softer. You can also place some brass rods and your knife in your vice, two brass rods on one side of the blade and a third on the other side. Slowly and carefully tighten the vice to flex the edge of the blade slightly. If it chips the edge, put it back into your kitchen oven at 400 degrees F. for about another hour and a half, letting it air cool to room temperature again. Do you flex test again. What you're trying to create is a steel crystalline structure that is hard, yet tough. Once your knife passes your flex test, finish it out and sharpen it.

You'll impress dear Mr. future father in law when you challenge him to a cutting competition. Let him use his favorite knife and see which one of you can cut the most slices through one inch rope before needing to touch up the cutting edge. Unless he has a custom made blade, the odds are that you'll easily outcut him. After you whoop him in the cutting competition, say respectfully, "Sir, you've inspired me to make this, and I want you to have it as a show of my gratitude."

His daughter will be yours, and the knife will have done it's job.

Go get em Tiger!

Ickie
 
Well I cut it out with the torch, then heated the blank up to dull red. It was pretty hard to get the whole thing dull red at once so I pretty much went up and down it for a while and let it air cool. I think it's still too hard because it's grinding really hard, I have an industrial like 7 inch angle grinder and I have it clamped down to a sawhorse and am roughing the shape. Slow going because I have to douse it with water every 30 seconds. I wish I had an anvil to put it on. It's starting to look like a knife, though, so that's exciting. I pretty much have one side ground down to the center point at the edge and just flipped it over. I don't know whether to just keep grinding at it and try to finish it with no further HT, or attempt to anneal it.

BTW I was thinking about shaping the tang to take two .45 grips as scales, since I have a bunch of them lying around.
 
trains are bad said:
Well I cut it out with the torch, then heated the blank up to dull red. It was pretty hard to get the whole thing dull red at once so I pretty much went up and down it for a while and let it air cool. I think it's still too hard because it's grinding really hard, I have an industrial like 7 inch angle grinder and I have it clamped down to a sawhorse and am roughing the shape. Slow going because I have to douse it with water every 30 seconds. I wish I had an anvil to put it on. It's starting to look like a knife, though, so that's exciting. I pretty much have one side ground down to the center point at the edge and just flipped it over. I don't know whether to just keep grinding at it and try to finish it with no further HT, or attempt to anneal it.

BTW I was thinking about shaping the tang to take two .45 grips as scales, since I have a bunch of them lying around.
Click to expand...

Since you heated it to a dull red, you'll need to heat treat it properly.
 
If you anneal it properly it will make it much easier when you start trying to do the hand finishing.

If you been doing knifemaking for a while with better steel... Trash the file (dont tell the dad)steel, buy some proper steel (dont tell the dad), make a nice knife, win the father, win the girl... nothing like a relationship built on a lie!..

Thats tongue in cheek by the way!
 
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