how to make a file knife?

[irishtoo]

a friend gave me an old very old file, 1/4 inch thick, 1 1/8 inch wide, with tang 15 inches long, without 12 inches long. its marked disston on one side and flat bastard on the other. i dont have assess to a forge. i do have a acetylene torch. what i want to make a riflemen knife. suggestions? thank you irishtoo

 

[Billnpatti]

Heat the file until a magnet will not stick to it. It will be glowing a bright red. Then pack it in ashes and let it slowly cool over night. The next day, it will be soft enough for you to file or grind to the shape you want. When you have it to the shape you want and are ready to re-harden it, heat it to a glowing red (magnet won't stick) and plunge into an oil bath. Motor oil will work fine. Then heat it in your home oven at 400 deg. for three hours. Turn off the oven and let it cool with the door closed. Once it has cooled, your knife should now be tempered to where it is hard enough to hold a good edge yet not brittle. Now you can polish it and sharpen it.

 

[Robert Egler]

Just don't do the motor oil quench in your garage if its attached to your house. Especially if the door to the kitchen is open. Trust me on this one. :redface:

 

[BEP]

Just don't do the motor oil quench in your garage if its attached to your house. Especially if the door to the kitchen is open. Trust me on this one. :redface:

Or if you're married. And wish to stay that way.

 

[Darkgael]

My knife kit:

Finished with temper colors left:

Pete

 

[LRB]

I don't think that is a suitable file unless you can forge shape it. How do you intend to shape it? At 1/4" thick, you have a lot of steel to remove if you intend to file it. An angle grinder will do the job, but will be nasty work. Motor oil for hardening steel is a very poor choice for more reasons than one, beginning with the fumes are quite toxic. Beyond that it will not harden the steel to the condition it really needs. Use a vege cooking oil, canola being the best of them. Heat the oil to about 125° before quenching the blade. My advice before you do any work on that file would be to lock it in a vise with about 3/4" of the end above the jaws, and hit with a hammer to see if you can break the tip off. If you can't break it, it is case hardened and not suitable for a knife. I would think a Disston would be good steel, but it will only cost you an inch of length to be sure. As to using a magnet to tell you when to quench, NO. A magnet can only tell you that you need more heat. About one or two shades of red above non-magnetic. You need to be in the heat range of getting into red-orange in very dim light conditions. Non-magnetic is 1414°. Your target heat would be around 1475°. Then quench. Temper at 425/450 degrees for two hours, twice. Use a separate oven thermometer to get a more correct temp. let cool to ambient in between heats, or water quench between. As far as softening the file to work on it, you can heat it to red 3 or 4 times letting it air cool between, and it should be soft enough to work. A long slow cool down should only be used only as a last option because of the amount of extra carbon in file steel. I wish you luck. You are going to need it.

 

[redneck]

use a barb q grill beaary it in a pile of wood charcoal. not brqets. start it and let it set till all are out and it is cold. no fuss no muss

 

no reason to turn it red or orange to fully anneal it so that it can be worked easily

just heat it slowly with your torch until it is fully dark blue and it will be a soft as it will ever get.

then grind it to shape by whatever means you have at your disposal, yes it will take a while but an angle grinder and the blade clamped down on a saw horse will make a much easier project of it.

after you get it to the shape you want, (make that 99%+ ) then it is time to reharden and temper the blade

you will need to bring it up to red, not orange
and by red that is in a relatively dark area, not out in the sun, if you are outside put the blade in a covered area like a 5 gallon bucket to shade it enough to see the color.

once red immediately dip it in motor oil, wearing gloves of course and hold it still, when i say dip it, i mean plunge it in point first and hold it there for a minute or better.

from there pull it out and further cool it in a bucket of water, to make it handy again.

now the blade will be as hard as glass and have a nice frosted grey appearance.

now time to temper it.

wait till momma has gone shopping and lay it on a piece of aluminum foil, on a cookie sheet in the oven.

i would bake the blade to 450F for an hour.

if you have not dipped the handle in the motor oil
it will be relatively soft and not likely to break during use.

if you have polished or shined up the blade prior to tempering in the oven you will be able to see the blade change colors, it should come out a very dark straw yellow to almost brown color.

i like my knives to be on the harder side, so if you want a tougher and less likely to break blade you can temper to a higher degree to where the color is more purplish.

there are a number of good books on handmade knives and blacksmithing at your local library, check out one and read up before you start... this will be a good project and if done right will last forever.

good luck
bob g

 

[LRB]

With all due respect, bringing hardened steel to dark blue will only give a spring temper. Not near as soft as it could ever be. It will be in the upper 40's to lower 50's in Rc hardness. Give or take some. Good files are usually best treated as 1095 steel, and require a fast cool in the quench. Motor oil will not do it as fast as it needs, and hardly even close. Canola oil heated to 125° will. A red heat may, or may not work well, but getting just into red-orange will, but not everyone sees colors the same. 1 or 2 shades of red past non-magnetic will do the job quite well. Considering what irishtoo has available for heat, he may be better off just trying to heat the edge area to quench temp. That would leave the upper area relatively soft and tough, then temper at least twice in the oven. The colors you get in a kitchen oven cannot be trusted. Unless the oven has never been used, there will be residual matter from cooking foods that will contaminate the atmosphere and produce their own colors regardless of how clean the blade is

 

[BillinOregon]

Wick, when are you going to write that book? I'll proudly be a charter subscriber to the first edition.

:wink:

 

[LRB]

There are already a lot of books out there. Both good and poor, and in some cases even bad. Even bad ones often have some good info, but one has to read enough to learn to separate the wheat from the chaff, plus talk to those who have already done it. We have a real metallurgist in our midst, or we did, but he seldom posts anything. James Kelly. Let me look and I'll see what I can find as to his advice on making a file knife. I have it somewhere. He posted on another forum for anyone to read.

 

[44-henry]

There was an article in the Machinist Workshop some years back that dealt with making a small knife from a file. It was well done and very basic.

I used to let students make some knives from files in our manufacturing processes class at UND. At the time I had a large quantity of files that were quite old and most were decent steel. Today I really wouldn't waste my time with this material. The material itself is generally in question meaning the proper heat treatment can be illusive, add to that the shape is generally not ideal and the file needs to be annealed or normalized to do any work with it. Also, there are far too many files on the market today that are casehardened and proceeding with one of these is pretty much disastrous.

That being said you can learn a lot making a knife from a file, mostly that there are a lot cheaper sources of good steal with known qualities that is much easier to work with. I like to play with odd materials as much as the next person, hence my recent blister steel escapade, however, there are much more practical ways to proceed with making a knife.

 

[Darkgael]

Wish that I had known a ot of this stuff when I was making that knife and the couple of others that went to my sons.
Nice info.
Pete

 

[LRB]

All very true, but, a good quality file, such as Nicholson has the potential to be a great knife for a determined beginer with a lot patience and few tools. The grain condition in a file is as good as it gets, and is often used as a standard to compare to. If one tempers the file as a first step, then is able to grind it to a blade (WITHOUT OVERHEATING IT), it will make a fine knife. But that takes a lot of time and more patience than most will have.