Input please

FOG2

FOG2

Joined
Nov 1, 2007
Messages
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I,m doing a passaround in the W&S forum with knives i made from NICHOLSON files. The temper was brought down in my oven and the file,s were NOT annealed and rehardened
Here is a post where one of them bent while being batoned.It did spring back partially and didn,t break so i,m thinking the tempering was ok but could have been better.Or am i expecting to much from just a tempering down of the file?

All input, opinions and ADVISE appreciated ! I would like to make these as good as they can be.

And here is the link:

http://www.bladeforums.com/forums/showpost.php?p=7049702&postcount=57
 
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What temp did you temper at and did you verify the steel type? Also, when grinding the blade, did you ensure to keep the temp down by cooling in water frequently? I would almost think that with the bend that happened that they were tempered down too far....
 
There is no way of knowing how much force that knife withstood. But if I had to guess I'd guess it was probably pretty soft to bend that way.

In my opinion, the primary purpose of tempering a knife down is so the cutting edge won't be brittle and chippy and so it will bend rather than break when abused. The purpose of not tempering a knife down is because Rockwell hardness is so critical to good edge retention.

A better way of putting this, if it held an edge well, it probably wasn't too soft. An experienced user could answer that question pretty quickly with use.

Rather than address gross structural issues with HT, I would look at the cross section and overall design too.
 
That knife is WAY too soft, that's all. You over-heated it in your tempering cycle. There's no way in heck you should be able to deform a good file like that unless it's been seriously over-heated. I'll bet you a free knife it doesn't hold an edge worth a damn. ;) Any good knife should snap before it takes and keeps multiple bends like that, and it should take a lot more abuse than just batonning it through wood to do that.

What temperature did you temper it at? If you aimed for 450-500F on your oven dial, which should be about right, it probably just means your oven is running hotter than the dial says.

This color chart will help you get in the ball-park. A reliable thermometer to put in the oven, so you can find out how hot it's really getting, would be even better.

You're not expecting too much, in my opinion. I've made several knives from Nicholson files just as you described. By tempering them back and grinding them to shape, being careful not to overheat the edge/tip. I started at the low range of temps, and found that two different ovens were both running a lot hotter than the dial said, based on temper color and performance.

Grind the teeth off to get a nice smooth, bright surface so you can judge the color after tempering, and start way low... preheat your oven for 300 degrees, let the file "soak" in there for at least an hour, and see how it looks. Too low a temp or too long of a soak won't hurt anything. It's no biggie to bump the temp up 25 degrees at a time until it starts looking good... nice straw/bronze color. Sand the color (oxide layer) off between steps (it won't take but a few seconds to do that) so you can see what's going on.

The file knives I've made and sold pass the brass rod test, cannot be bent or broken with hand-pressure when vised-up, do not break when I whack the spine HARD against my vise (no anvil here yet :\), and take and keep a very fine edge quite well. I have no qualms about guaranteeing them.

Having said all that, yes you're better off starting with new steel and heat-treating it from the ground up. Or, at least annealing and re-heat-treating your files, for various reasons. But YES it can be done... it's not real difficult to make a file knife as you described, that will far out-perform the majority of factory-made knives you see.

Have fun!
 
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P.S. Stick with Nicholson or Simmonds brand files. I've had really good results with both, once I learned how to temper them close-to-properly. There may be other quality brands I'm not aware of. Don't even play with cheapo India or China files.
 
The recipe in the last paragraph of this post is what i used.

http://www.bladeforums.com/forums/showpost.php?p=3404412&postcount=82

I watched them for color and pulled them out at straw yellow.

*edit* After looking at the color chart they looked more dark yellow/orange which would indicate 480 degrees in the chart. Likely that was the problem ????

When grinding them i did it bare hand and dipped them b4 they got hot so i know i didn,t ruin the temper while grinding.


If we break the knife and look at the grain will that tell us anything ?

As far as holding an edge thats one thing the passaround is designed to find
out.

Thanks for your advise !
 
Some files are not solid hard steel. Some are case hardened mild steel, so they're hard on the outside and soft in the core. If you made a knife out of a case hardened file, it would do exactly what you see there.
 
I have some simmons files that are exactly what Nathan described
do yourself a favor and buy NEW steel from Aldo Bruno or Kelly Cupples and if you can't do your own heat treat (not really that hard if you get 1084) get someone to do it

-Page
 
It looks like your knife almost totaly lost it's quench. Did you use your kitchen oven for the temper?

Something strange like that happened to a friend of mine. He got a file he wanted to anneal in his coal forge. He have a good experience with it, he's been forging for tfour years now, and knows how simple carbon steel behaves. But this time, though he did everything alright, the blade just did not take quench. We suppose it have been totally decarboned, but it still extremely strange, as file are generally about 1.3% C (up to 1.7% i believe), and it just can't be lost that easily.

Maybe there is something with carbon in your case too. Some combustions "drains" carbon out of the blade, that's precisely what is done when refining raw cast-iron from blast furnace into steel... but that's at liquid state of matter. You should try to anneal your blade, re-quench it, and re-temper it. And don't try to hard to understand what happened, sometimes we just can't find the answer... maybe it's just a message from Ephaestus: "Do it again, boy!".
 
Folks, please read some of the threads in the NEWBIES GOOD INFO HERE stickies
first, chances in this day and age that your file is actually "file steel" are slim
it is likely mild steel that has been case-hardened, much simpler and cheaper, and that is what the game is all about these days.

-Page
 
FOG2 said:
The recipe in the last paragraph of this post is what i used.

http://www.bladeforums.com/forums/showpost.php?p=3404412&postcount=82

I watched them for color and pulled them out at straw yellow.

*edit* After looking at the color chart they looked more dark yellow/orange which would indicate 480 degrees in the chart. Likely that was the problem ????

When grinding them i did it bare hand and dipped them b4 they got hot so i know i didn,t ruin the temper while grinding.


If we break the knife and look at the grain will that tell us anything ?

As far as holding an edge thats one thing the passaround is designed to find
out.

Thanks for your advise !
Click to expand...

I wouldn't rely on any color charts for tempering any knife, after the results I got with my oven muffle.

After a controlled 2.5 hour temper +/- 5° the colors I got were way off the charts according to the the temper color charts. 400° temper after 2.5 hours reveals a deep bronze color which, according to the chart would be around 500° and 420° @ 2.5 hours showed a full blue color which the chart indicates is about 560°.
 
To clarify as seen in my 1st post it was a NICHOLSON file, and yes i understand
about using new known steel( i have made several cpm154,ats34 knives,1095 etc.) BUT FILE knives interest me so i want to learn to do them AS BEST AS I CAN. Hence this thread and the passaround.

Yes the temper was done in my kitchen oven. Im thinking i need to get a good THERMOMETER so i don,t have to rely on colors.

Will BREAKING that knife and looking at the GRAIN tell us anything more ?

Any more advise anyone can give on making knives from NICHOLSON files is greatly appreciated as are the answers i,ve received.
 
FOG2 said:
Will BREAKING that knife and looking at the GRAIN tell us anything more?
Click to expand...

That's an interesting question, and I look forward to the more experienced guys answering it. All I can say is that well-hardened steel I've broken on purpose hardly shows a "grain" on the break; it looks almost milky grey and smooth. On the other hand, machine parts that I've had fail prematurely showed a definite large "grain" at the break.

Maybe you could find a machine shop nearby that would Rockwell-C test the blade for you? I'm also looking forward to any recommendations on thermometers; I need one for the same reason. Is a regular dept. store oven thermometer accurate enough for our purposes guys?

I'm like you; I mostly work with new, known steel to help me get the best, most consistent results... but I also like file knives. There's just something cool about them. :) But you have to fiddle with them a bit and test thoroughly to make sure what you're dealing with. I'm glad to see you're willing to test them hard. :thumbup:

The comments above about not completely trusting color charts are very true. Like the brass-rod test, it's only a guide-line! I didn't mean to imply that a color chart is any kind of carved-in-stone rule. There's just too many variables involved.
 
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Just a different angle on this...

You could always make the tools and then cut file teeth into new (known) steel BEFORE you grind your knife.
 
FOG2 said:
To clarify as seen in my 1st post
Yes the temper was done in my kitchen oven. Im thinking i need to get a good THERMOMETER so i don,t have to rely on colors.

Will BREAKING that knife and looking at the GRAIN tell us anything more ?
Click to expand...
IMO, breaking your knife to see the grain won't give you any information. Sorry to say this, but it's already like chocolate, no properly heat treated steels (at least for a knife) would take and keep such angles. Grain size is involved mostly when toughness is abnormaly low, as longer grain joints/borders caused of bigger grain size weakens the blade (maybe that's something like: the fracture have to do less direction changes to propagate... as electric arcs take less electric power to form in lower pressure or in vaccum than in normal air). Here, your blade just doesn't break, but bend.

And instead of a thermometer, i thought to something. This temp/color scale is for basic steel, so may be wrong for these file. But, you could use a blanked or polished mild steel or 1084-like steel to use as witness of the temperature. Between each temper, a small sanding paper pass to make it clean again, and you go. And if you can, use a bakery or pastry mode or such, something where air is constanty moving, cause i've heard that at these "low" temperatures, there is no homogenity, and that there could be some temperature difference in different point of the oven. Professionnal tempering ovens have a fan, i guess it's not just to look nice.
 
In my opinon if you break the knife, the grain will look fine if the file was properly heat treated at the factory. The tempering that you did in your oven should not be enough to cause grain growth. If the grain is large then the file was poorly heattreated before you did anything to it. I believe that you used too high of a tempering temperture and brought the RC down too low. BTW a knife is not an axe or a wedge....
 
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