Crunchy/Chippy edge on a file knife

Q

Quinnshield

Joined
May 9, 2019
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Hey guys, I've recently made a small utility knife from a file, this is the first time I've worked with one. When I got to the sharpening stage I realized the edge was just crunching or chipping away as I sharpen the blade. Production process is as follows: I annealed the file at approximately 1400 deg before forging. After all was done I normalized then heat treated the blade at approx 1500 deg, quenched in canola oil at 160 deg and tempered at 425 to a straw yellow. In short, what the heck did I do wrong and why is this knife chipping away as I sharpen? Is there any way I can fix the problem? " all temperature measurements are in Fahrenheit".
 
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Bigfattyt said:
Any idea what the steel in the file was? Old file, new file?
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It's a newer Nicholson bastard file. No idea what the chemical composition of the file is. I was expecting it to be something similar to O1 but I'm convinced I was wrong.
 
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Quinnshield said:
It's a newer Nicholson basterd file. No idea what the chemical composition of the file is. I was expecting to be something similar to O1 but I'm convinced I was wrong.
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A lot of newer files won't properly harden like a knife.


It would not happen to be made in Mexico??


They are case hardened. The older files, made in the USA are supposed to be better steel.

I've heard a lot of people say they cant make knives out of the new ones.
 
Bigfattyt said:
A lot of newer files won't properly harden like a knife.


It would not happen to be made in Mexico??


They are case hardened. The older files, made in the USA are supposed to be better steel.

I've heard a lot of people say they cant make knives out of the new ones.
Click to expand...
I may have to agree with not being able to make a knife from it! On the file it says " Nicholson made in the USA, Mill Bastard". I googled it before working the steel and according to the info I found it said to treat it like O1, but I can tell you that was definitely wrong. If you give me a few I'll try to post some picture of the remaining portion of the file.
 
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Here is the knife and the remaining portion of the file it was made from.
 
Chippy edges are caused by:
Temper too low - A file knife should be tampered at 450F.
Edge angle too acute - 20° per side is a good starting place. Increase angle 5° if the edge still chips.
Overheated steel - This is a common error with back yard HT. The steel heats up too high and the grain gets large. Chinks fall out in sharpening and use.

As an added note, 160°F is too high for the oil. Try 120-130°F for better hardening.
 
Nicholson files are between 1% and 1.2% carbon. Heat treat between 1425f and 1450f for best results. You will get inconsistent structures (mixes of plate and lath martensite, and retained austenite) with hard and soft spots with 1500f.
 
Thank you guys very much for the information, it's much appreciated! Do you think it would be possible to salvage this knife by re-tempering the blade? Or would it need to be torn completely apart, normalized, then re-heat treated as well?
 
I've had exactly the same experience with a file knife. It was just for play, and works pretty well with that toothy edge, but I wouldn't let it leave for someone else's kitchen. Mine was probably over-annealed.
 
OK I managed to save it! I wrapped the handle in a very wet cloth and re-tempered the blade with a map gas torch to about 450 deg and it's working out perfectly! During sharpening I'm able to develop a wire edge now rather than just chipping away. Hopefully I'll be able to get it shaving sharp after stropping! Thanks again for the great info y'all !!!
 
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Bigfattyt said:
A lot of newer files won't properly harden like a knife.


It would not happen to be made in Mexico??


They are case hardened. The older files, made in the USA are supposed to be better steel.

I've heard a lot of people say they cant make knives out of the new ones.
Click to expand...



I'm pretty sure that the newer Nicholson Files (made in Mexico etc.) are still 1095, but are just hardened to a lower RC so they dull easier. It's apparently the rasps that are case hardened, at least the newer ones, have no idea about older ones. Another problem with them from what I've read in the past, IIRC, is that the quality control is much lower and the teeth aren't cut as consistently, not sure if it's still the case but I know it was recently after they moved to Mexico.


Just found the post I was trying to remember that Aldo made not too long ago, here is what he said concerning the older and newer Nicholson files:

Aldo Bruno said:
The present day Nicholson files are 1095. So are the Black Diamonds. They were a company that Nicholson bought a long time ago. They left the name for the sake of sales. At the time they were using a 1.30 carbon steel that was produced for them by Bethlehem. At one point they came up with new processing,but the 1.30 Carbon steel was cracking with the new process. It was decided to use the 1095 which works fine. The older files were 72/74 RockwellC. The new ones come in at 65RC. If you want to make a knife out of 1095, call me! The time you save alone is worth it! ....unless you have your heart set on making a file knife! Then by all means buy a Nicholson or Black Diamond. Be sure not to use a rasp though! They are made out of CASE HARDENED 1045.
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FWIW, if it's a USA made file, no matter what brand, Black diamond, Nicholson, Kearney & Foot (K&F), Disston, Simonds and so on, I'm pretty sure they are almost always good to use for knives. I have yet to encounter a case hardened file, even the "India" ones I got years ago from HF (at least the ones I got around 2011) would harden. I'm not saying there aren't any case hardened files (probably most of them would be from China), just not as many that I used to think when I first got into knife making.

If in doubt, do a spark test all the way through the thickness of the file and do a quench test to see if it breaks in a vise, then look at the size and "color" of grain all the way through, etching in FC after breaking may help expose any unhardened steel by etching a lighter color. You could even go as far at to grind off a good amount from each side leaving mostly the center of the file and then do a spark and quench test. Just my $0.02 :)

~Paul
My Youtube Channel
... (Just some older videos of some knives I've made in the past)
 
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coldsteelburns said:
I'm pretty sure that the newer Nicholson Files (made in Mexico etc.) are still 1095, but are just hardened to a lower RC so they dull easier. It's apparently the rasps that are case hardened, at least the newer ones, have no idea about older ones. Another problem with them from what I've read in the past, IIRC, is that the quality control is much lower and the teeth aren't cut as consistently, not sure if it's still the case but I know it was recently after they moved to Mexico.


Just found the post I was trying to remember that Aldo made not too long ago, here is what he said concerning the older and newer Nicholson files:





FWIW, if it's a USA made file, no matter what brand, Black diamond, Nicholson, Kearney & Foot (K&F), Disston, Simonds and so on, I'm pretty sure they are almost always good to use for knives. I have yet to encounter a case hardened file, even the "India" ones I got years ago from HF (at least the ones I got around 2011) would harden. I'm not saying there aren't any case hardened files (probably most of them would be from China), just not as many that I used to think when I first got into knife making.

If in doubt, do a spark test all the way through the thickness of the file and do a quench test to see if it breaks in a vise, then look at the size and "color" of grain all the way through, etching in FC after breaking may help expose any unhardened steel by etching a lighter color. You could even go as far at to grind off a good amount from each side leaving mostly the center of the file and then do a spark and quench test. Just my $0.02 :)

~Paul
My Youtube Channel
... (Just some older videos of some knives I've made in the past)
Click to expand...
Oh yes, I always spark and harden test mystery steels, as well as do as much research as possible to find out exactly what kind of steel each particular item I'm working with is lol! I don't keep ferric chloride in my shop, I don't have much use for it yet as I don't have the equipment to make pattern welded steel. As my business grows hopefully I will someday!
 
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