Next step in knife from file

hughewil

hughewil

Joined
Apr 12, 2011
Messages
943
I have a old 12 inch Heller nucut file I picked up for a $1 at a thrift store.

I anneled it (pretty sure that worked since ir wasn't to hard to cut with ahacksaw)
cut it down with a hacksaw
shaped it and started a grind with a bench grinder
finished off the bevel edge with a hand file

now i need to finish it up. How do i heat treat and temper it?

I think I heat it like I did ti anneal then quecnh it in conalla oil
then heat the oven to 450 and put it in for an hour, take it out and let it cool.Do this three times.

Is that corect?

This is my first knife, but doubt it will be my last. I can get old used files pretty cheap. I figure i cna make some knive sfor myself, my father in law, friends, etc.
 
First question, what is your heat source? did you do a heat/quench/break test to make sure it is actually hardenable?
You should put your city in your profile location rather than the model number of a knife blank design you like just in case there is an experienced smith living next door to you who might offer to help you (Hell you could be living across the street from me)

-Page
 
updated my profile.

As for heat source just a firepit in the backyard. I built a fire, stuck the file in the coals and when it started glowing I put rocks over the top to insulate and let it sit and cool slow overnight. I don't know what the test you mentioned is so no I didn't do one.
 
Take a small piece of the file you cut off and heat it up past the point where a magnet will not stick and quickly plunge it in the canola oil. Then put it in a vise and while wearing safety glasses stick it in a vise and hit it with a hammer. It should break like glass. You are going to have a hard time getting a good heat treat with a backyard fire pit. You actually need to be about 50 to 75f above non magnetic. If you are to cold, you not convert all the steel to the right structure, to hot and you get grain growth and a brittle blade. Do you have access to a propane torch? If so grind the file marks off a piece of cut off, grind and sand smooth and heat to non magnetic with the torch in a dim lit area, watch the steel as it changes a couple shades of red, quench and break. Should shatter and the grain be very similar to the grain of a broken file. Try it on a few pieces then do it to your knife. With the knife keep the flames off the edge and tip as they are thin and will heat way faster. keep the flame moving near length of the spine and let the heat flow to the thin areas. When you are above non magnetic quench to cool enough to touch. Go straight into the oil and move it in a cutting motion. Then immediately temper in an oven at 425 for 2 hours cool, then 450 for 2 hours then cool. You need to have about a dimes thickness at the edge when you do the HT and then use sand paper backed by a bar of steel to remove the layer of decaronized steel that will form from the HT. Work from 120 grit (220 if you had a better finish before HT) to a finish you like. It will sand faster if you clamp a stiff bar of steel behind the blade so you can put some pressure on it will sanding.

There has been a ton written on this. Good files are 1095 or W2 and have an excess of carbon. (Hypereutectoid steel) This makes the HT temp higher and more critical than a steel like 1085 which is better for backyard HT as it converts right at non magnetic. I write this because you are where I once was and I want you to experience the satisfaction of making your own knife. If you really want to get into it and make the best you can make you really need to read the stickies at the top. You knowledge will be increased by a huge amount faster than any other way i can think of. See Kevin Cashen's threads post #8 in the stickies about your steel.

Enjoy and good luck
 
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Your first concern is whether the file is hardenable (high carbon steel throughout) or case hardened (thin layer a few thousandths thick surrounding mild steel) which is why Jim suggested you cut off a small piece and do the quench and break test. My first knife was made from a Nicholson file 31 years ago http://www.sunshadowdesign.com/knives/596.jpg

but that does not make it a good idea. I was 14 working in the basement after my parents went to sleep using instructions in the Popular Mechanics Do It Yourself Encyclopedia, I annealed the file with a propane torch and filed it seemingly forever. I finished several other knives before I finished this one, finally while I was in college where a metals grad student taught me heat treating and got me access to the lab kiln. Your first issue is that you do not have a controllable heat source, the second issue is that you have no idea what steel you are working with, so you have no idea how you are supposed to heat treat it (or if you will be able to heat treat it at all)

My first bit of advice is forget files, if they are good steel (most are not these days) you are going to have to get below the teeth and the stresses under the teeth. Get some 1084 from Aldo http://www.njsteelbaron.com which can easily be heat treated even with a backyard firepit. You will not be limited by the geometry of the file, and you will not have to undo all the work that went into making the metal a file. You can tell when a simple steel like 1084 gets to the critical temperature of Austentite formation (Af phase change) not by feeling for it with a magnet (All steels lose magnetism at 1414 f regardless of when actual Af happens which is about 50 degrees short of what you need for the lowest temperature transforming steel, and several hundred below high alloy steels) by looking for the bright/shadow line of decoalescence and recoalescence. When you bring the steel up to Af (the beginning of "critical") the phase change takes a bit of energy to kick off, so just before the transformation the glow dims just a little (visable in dim light) and as the steel comes back through Af (recoalescence) the transition gives off that little bit of energy and there is a little flicker of brightness at the transformation line

-Page
 
Thanks guys for the info.


What does it mean when the metal gets super hot and changes color (gets darker) and becomes brittle? Doess that mean its good for heat treat?

I might try some of the 1084 steel, but it look slike they come in long bars. I saw 01 bars on texas knife makers websire that were smaller. does 01 work well?
 
you can use your hacksaw to cut up the large bars. 1084 is awesome, and is much more predictable than files. go for it. 01 is hard to heat treat in comparison.
 
Read this thread
http://www.bladeforums.com/forums/s...rst-blade-(newbie-perspective)-Please-Critiqu

On the colors the forging color chart is for a dim light while the steel is hot. The tempering one is about the color the shiny steel will turn to as it is heated too. I wouldn't trust the tempering color as different steels look different and a bit of oil or something can effect this color.

If your steel gets brittle it will harden. But, define super hot. Above 1500 file steel will get grain growth and become even more brittle no mater how you temper it.

READ
 
Page - I am absolutely in agreement with you, theoretically speaking. I have a practical concern (one of my favorite steels is low manganese 1075 which is at the very low end of heating and easy to treat by using magnet and going a few seconds more and making things even and then quenching). But, my other is W2, where really watching for the transition and attempting to soak for a period just at or above transition temps is quite important. OK, now the real issue: I can easily see when the transition happens on a falling heat because I have the steel out of the forge in a dark garage, but I cant readily see the transition happening inside the forge. The best I can do is to take the blade from the forge periodically and look while on the rise. Since I have a propane forge with no pyrometer, this is also a good way to slow the heating, as well as keep the steel just above transformation for a period without letting it get to hot. Not as good as a real constant soak, but better than not doing it at all. Usually, I can see when parts of the edge are crossing through the transformation by the shadows (often, much of the blade is covered by clay, too).

So, any suggestions to help the practical application of the technique (besides buy a pyrometer)?

kc
 
kevin -the professor said:
Page - I am absolutely in agreement with you, theoretically speaking. I have a practical concern (one of my favorite steels is low manganese 1075 which is at the very low end of heating and easy to treat by using magnet and going a few seconds more and making things even and then quenching). But, my other is W2, where really watching for the transition and attempting to soak for a period just at or above transition temps is quite important. OK, now the real issue: I can easily see when the transition happens on a falling heat because I have the steel out of the forge in a dark garage, but I cant readily see the transition happening inside the forge. The best I can do is to take the blade from the forge periodically and look while on the rise. Since I have a propane forge with no pyrometer, this is also a good way to slow the heating, as well as keep the steel just above transformation for a period without letting it get to hot. Not as good as a real constant soak, but better than not doing it at all. Usually, I can see when parts of the edge are crossing through the transformation by the shadows (often, much of the blade is covered by clay, too).

So, any suggestions to help the practical application of the technique (besides buy a pyrometer)?

kc
Click to expand...

Yes, if you can keep your lighting the same you can memorize the color just above where the shadows start and you will have an idea what the color is that the transition happens at. You have the transformation temperature for your steel even if you don't know what the number is. The fun thing about "Blackbody radiation" is that the color radiated is the same regardless of whether you are looking at steel or insulation if the item you are looking at is the same temperature and not having the energy it is radiating overpowered by another illuminant. If you keep your forge at or slightly above the color you observe just before the shadows start when you are heat treating, you are going to be in the ballpark. If you pull an "indicator piece" that is sitting next to your blade made out of the same steel out and within a few seconds you see the slight bright band followed by the shadows traveling across it you know you are just above Af with the blade, let it sit for a few minutes (being sure to try to keep the observed color of the forge constant at the color just above the transition temp color) then quench it.

If you understand what is going on metallurgically in the steel and how to read what is going on, the numbers you get from sophisticated equipment are useful, but with simple steels you can read the steel and get by without them. You are more likely to be consistant with the fancy equipment (and ultimately being able to consistantly get the best results the steel can give you makes getting all of the fancy equipment relevant) but you can get a good baseline by observing carefully
 
thanks, Page. That is basically what I am trying to do. With short blades, I should get pretty good at it. With longer ones, where I have to keep the blade moving to keep the temp even... well, lets just say I try to make a lot of those out of the low mang 1075 so the magnet is a very close guide.

I will try to run one piece through in a warm up, and then try to get the forge to hold at the color about where that piece (same steel, sim cross section) changed. I.e., trying to get the forge just over the transformation temp to get the carbon dissolved and inside the molecular structure to give me martensite, and then hold. I did this once with a blade of L6 so I could soak well, and it worked (apparently, given my level of testing equip, I won't say with too much confidence).

I don't normally stray from the 15n20, 1075, w2 grouping because I don't have sophisticated equip.

thanks for the advice. Much appreciated.

Hugh (I guess, forgive me if your name isn't Hugh) - all of this worrying shows why we are suggesting getting a known bar of steel. Aldo or Mcmaster-carr or online metals will ship one to you in a couple of days. Aldo is best about regulating and telling you the actual composition of the steel you buy, which is wonderful (plus, he is a hell of a guy).

If you do harden a piece of your file, and it gets harder than other files and then breaks, you are likely ok. Nicholson has used either w1 or 1095 for many years, and if you have one of their files and it passes this test you are ok. These two steels are essentially the same thing, and make good knives (and good hamons if you clay heat treat them). I recycle my old Nicholson (read used - they are new, I break out a brand new set of 2 files every time I start a new sword, so I have a lot of barely used files laying around). These become hunting knives with hamons for friends and family. They do heat treat easily, compared to the high alloy stuff which is beyond my level of sophistication.

have fun, that is the most important part!
kc

kc
 
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