View Full Version : How whould I soften up a nicholson file for cutting and grinding
06-27-2011, 07:18 PM
I need to know how to soften up a large nicholson file. I have a few of them that I would like to make knive out of. I have just gotton my suger creek kiln. Can I just heat the file up and let it cool of in the kiln?
06-27-2011, 08:07 PM
Heat it up, then cool very slowly.
You're gonna have to see what works for you.
Shutting down the kiln and leaving the piece in it overnight might work.
Some people bury it in sand.
Some people use pearlite.
Whatever insulates enough for you to cool it down slowly enough.
Personally, I consider it at least an overnight process.
When cool, you need to find out if your anneal worked. Given the nature of your project, I would test it with another working file. Use a good file and see if it bites into it or skates across; if the file bites and wants to cut, your piece is annealed.
But to have that method work correctly, you need to remove any scale that might be incurred during the heat.
The scale is extremely hard and may cause the test file to skate over your workpiece, even though your workpiece itself may be annealed. Not to mention that trying to file on scale will quickly make your "good" file become your next workpiece.
I like to soak the workpiece in vinegar overnight. The next morning, brush off the loosened scale, then check to see if the anneal worked. Some people with less patience can use abrasives to remove the scale. Grinders, sandblasting, etc.
06-28-2011, 03:30 PM
i have not tried my kiln for that yet, but have a big bucket of wood ash,then heat and bury in the ash overnight and it worked pretty well dont now if at softest state that it could be but i could file it ok. i forgot do you have a programmable kiln i saw a thread somewhere on the times for that mine infinite control so i cant set times
06-28-2011, 03:49 PM
I would do a sub-critical anneal. A standard anneal will probably work well enough but the sub-critical cycle will make it cut and drill like butter and should put it in an ideal state to start your HT cycle.
Nicholson's files are (or used to be at least) a modified W-1, according to a company rep. For a sub-critical cycle I would hold at 1300 for 2 hours and just turn the oven off. Properly you would cool 50 degrees per hour to below 1000 degrees or so but with a simpler alloy I think this isn't as critical. Kevin or someone else might pop in to inform me otherwise on that point, though:52:
Just for the record. No one seems to get the same answer from Nicholson twice, as to the exact steel. Any time I've seen the results from an independent test, it was like 1095 with extra carbon, and I believe a touch of vanadium. Believe it or not, I saw a recent test on Harbor Freight Chinese files that gave 1.3% carbon. But anyway, I agree with you on the sub-critical anneal. A standard anneal does not do it all that well. I have in the past, made many blades with Nicholson files, and merely heated them to a red-orange, then let them cool. At that point, you could drill or file them well enough, and as good as a standard anneal, but I think what you say would be superior.
07-01-2011, 06:57 AM
I agree with these guys that a sub-critical anneal is the best way to go BUT
Something I've always wondered about using files ? UNLESS your forging to shape (in which case an anneal is a mute point) -
Why not just temper it at your desired temp. and profile it with a 36x belt ?
-It's already got a professional heat treat by someone who knew exactly what the steel is
-Drilling shouldn't be a problem. Just use a torch to draw the tang past the blue range to grey twice. (I haven't done this to a file but I've done to fully hardened blades)
07-01-2011, 07:54 AM
What Josh said. I've made several file-knives that way (by simply tempering back and stock-removing) and it works very well, with very little chance of messing up the existing HT.
Of course if you want to forge a big'un, the sub-critical anneal makes a lot of sense.
J S Machine
07-08-2011, 11:46 AM
I have a broken file I'd like to try this on. It says "BAHCO OBERG, PORTUGAL 110-14-1. There is a pic of a half moon smiling beside that name.
It's a pretty big file, or was - about 14" long and 1 3/8" wide. I have had it laying around for a while and thought I might try this.
Thanks for the thread and everyone for the repsonses.
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