Making a dagger neck knife from a file,Questions

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CrazyCraig

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Apr 15, 2021
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I am 61 and I am going to make my first knife and have a few questions .

I am wanting to make myself a dagger neck knife with both sides sharpened ,from a file ,I have several files but dont know how to test a file to determine its suitability for making it into a knife as I have read that some files are through hardened and others are case hardened only.

I have a bench grinder and angle grinder and intend to basically grind away everything that does not look like the knife that I want to make.

I may just leave it as it after grinding or put it in our kitchen oven and try to temper it somewhat after making it.

I am wanting to use about 4 inches of the file for the handle (which I may of may not wrap with a bit of paracord)with about a 3 1/2 to 4 inch blade .

I want the knife to weigh 4 ounces of less.


Given what I am wanting to do

What is the easiest way to find out if a file is through hardened or just case hardened ?

Best way to grind the edges(will be using a whetstone when it needs sharpening)?and will it need to be tempered to sharpen on a whetstone?

About how thick and wide does the blade need to be to be fairly sturdy and to make the weight of 4 ounces or less ?

Thanks
Craig
 
Aneal the file, harden the tang but don't temper it.
Hit it with a hammer. If it brakes you have a good chance the file will harden, if it bends take an other one.

And do as Stacy says, reas, read read first.
 
Walter Sorrells has a good video using a right angle grinder to make a knife. It's worth a watch.
 
CrazyCraig said:
I have several files but dont know how to test a file to determine its suitability for making it into a knife as I have read that some files are through hardened and others are case hardened only.
Craig
Click to expand...
Make shallow notch with angle grinder about one inch from the tip of file ,fasten it to the vise and use hammer .............
If it is case hardened you will easy make scratch in middle of break part of file.
 
I had a file that was case hardened. When I ground the end a bit and then etched in ferric chloride the outer part of the crossection turned black and the center was brighter. Also if you snap a piece of fully hardened file it will be very uniform and fine grained if its case hardened it will not be so brittle and will have some plastic deformations and rough grain.
 
Find an old rusty file that says Nicholson at a yard sale and it'll likely be through-hardened.
 
Stacy E. Apelt - Bladesmith said:
Welcome crazycraig. The custom search engine in the stickys will find many threads on this subject. Here are a few:

How to Make a Knife From a File | BladeForums.com

Making a file knife, short tutorial | BladeForums.com

https://www.bladeforums.com/threads/making-a-blade-from-a-file-in-9-easy-steps.907457/

https://www.bladeforums.com/threads/metallurgy-in-that-making-a-file-thread.916179/
Click to expand...

I read the links,thank you

I like going the route that that does not require annealing and then rehardening.

I want to use the hardness of the file as is to grind to the shape I want it and then temper it in the oven to make it less brittle.
As you said I realize that it will be little more than a shank but for my purposes as a cutting tool for general knife usage and last ditch self defense tool I think that will serve me just fine.

With a grind that will be easy to sharpen on a soft Arkansas whetstone and then use a hard stone and strop for better sharpness.

I have see some knives with both edges sharpened that looked symmetrical on both sides of the blade and others that were flat on on side of the blade with all the tapering on the other side .
Is one easier to make on a bench grinder or belt sander ?

Thanks



Still curious as to what thickness and width to use that will give me a knife that is 4 ounces or less and still maintain enough stiffness for penetration
and what type of grind would be the best and easiest to sharpen with a whetstone.
 
fitzo said:
Find an old rusty file that says Nicholson at a yard sale and it'll likely be through-hardened.
Click to expand...
I have read that somewhere around 1990 that Nicholson files were were made overseas and not good steel like they were ?
Is that true?

Thanks
 
Dimitar Popov said:
I had a file that was case hardened. When I ground the end a bit and then etched in ferric chloride the outer part of the crossection turned black and the center was brighter. Also if you snap a piece of fully hardened file it will be very uniform and fine grained if its case hardened it will not be so brittle and will have some plastic deformations and rough grain.
Click to expand...
Thanks
 
Natlek said:
Make shallow notch with angle grinder about one inch from the tip of file ,fasten it to the vise and use hammer .............
If it is case hardened you will easy make scratch in middle of break part of file.
Click to expand...
When you say tip of the file are you talking about the using end of the file or the tang ?
Thanks
 
This is a picture of my casehardened file when I cut the tip and then etched it.


E0005fc.jpg
 
Rick Marchand said:
Are you sure that's case hardening? File steel is shallow hardening.
Click to expand...

Hmm maybe I'm not using the right term. It's hardened only on the outside , but I thing the whole thing has the same carbon content, because when I cut a small piece , heated and quenched it , it fully hardened. It was not a case of carbonized surface layer . Sorry if my post was missleading :) And is it right to call it differentialy hardened then?
 
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