Knife file

[steve202]

Hello.

Would or could file metal need or recieve any treatment to stop it from being brittle?

Been reading a knife makers forum and a few people have made knives from old files. I like the idea and fancy a go. I know the easy answer... join up and ask them! ... just thought i would ask the metal folks here first.

Here is an example

 

[..DAZ..]

Never done one from a file before, but I have made some from an old automatic saw blade. Extremely tough and durable but they were sometimes a bit of a b*tch to sharpen. To stop it being brittle, I "think" a rough guide would be to heat it to straw colour, then let it cool naturally, but I could be way off the mark. The guy that taught me a bit of toolmaking always told me that with tool steel you would heat until cherry red and cool in oil, sand back to shiny metal and then reheat to the colour of straw and let it cool naturally. The reason for sanding was so you could see the colour change. I still have a gasket scraper I made using the above method, I have had it for 14 years now and it still works great.

daz

 

[eil]

Don't know about making knifes from files but have but have seen them made from rapidor hacksaw blades though
Beat me to it Daz

 

[pedrobedro]

Have a look for Greenpete's videos on youtube or on his website, I think he covers it on there. You can't make them from modern case hardened files but older ones have higher carbon content. It needs annealing before it can be worked then hardening and tempering after to make it into a usable blade.

 

[steve202]

Cheers lads. I like the way the hatchings are left on the blade in that pic.

I got lost from the knife forum while surfing as you do and ended up on some metal forging and Anvil fanatics site.


Something i would love to try if i ever get the chance or time.

Anyway i have an old file here which seems suitable. I will crack on and see what mess i can make of it.

 

[..DAZ..]

Good fun making knifes. I have made a couple with mahogany handles and the last one I made I sushi sharped it, goes blunt real quick but it's just as sharp as my straight razors. Can't really use it for anything though as the blade is too fine. The guy that got me into welding used to make his own knifes from scratch and has even made a replica of the William Wallace sword that is in the monument in Stirling. The best one I have seen of his is a bowie knife he made as a prize in a shoot he goes to every year. Takes a lot of skill and sweat to do that.

daz

 

[pidgeon chit welder]

If my memory is correct files used to be made from cast steel that was then forged , set with teeth ground in it , then hardened and tempered to just under the dark blue , the tang or handle end was normalised
On some tangs you could see the end of the blueness just before you got to the teeth.
So my guess is that by heating a file to cherry red and letting it cool you will be able to reset the steel and make the knife by cutting & grinding , then harden it to blue on a redhot steel block , quench in water, rub off the colour and temper it to light straw by laying the finished item on an orange red hot block of steel using pliers ..having the back of the blade along the block and watch the colour move to the cutting edge & then quench in oil.

 

[steve202]

Its a great skill for sure and i have a lot of respect for it and those that can do it.

 

[Ratty]

I've made a couple of knives using hacksaw blades, only about 2"-3" long tho'....just the right size to hang from my ear and perfect for emergencies

 

[Bsmith]

Heat the file until cherry red and bury it in ashes until cool to soften or what I oftens do if not in too much hurry is throw the file in a solid fuel household fire or stove, its annealed the next day. Make the knife, polish, heat only the sharp edge to straw colour and quench in water, sharpen and thats it.

 

[Shox Dr]

heat only the sharp edge to straw colour and quench in water, sharpen and thats it.

How well does it keep the edge

 

[Bsmith]

How well does it keep the edge

Difficult to say Shox Dr, depends how sharp it is and what its used for. We could probabley compare it to the life on the edge of a Stanley knife blade which will last a long time sharpening pencils but will soon dull cutting carpet.

 

[pidgeon chit welder]

BS.
How do you harden the blade ?
For by what you have said you normalize the steel and then temper it.
I was always under the impression that what we did was to harden to dark blue , quench then reheat temper to straw & quench .
This would give the tool toughness without brittleness but still have great hardness & durability .

If you only straw heat the edge of the blade from the cutting edge backwards into the blade body you will not have the high quality heat treatment running out from the blade back, it will be just a limited tempering which to my reckoning will be be liable to breaking off and/ or chipping along the cutting edge.

For our cutting tools made from HC steel to pass muster as hardened and tempered tools they had to be hammered cutting edge first in to the base of the anvil which is wrought iron with a 2.5 lb. engineers ball pene hammer , any rubbish tool would blunt or snap .

 

[pedrobedro]

I've not made a knife from a file but I made a little folding knife for a web based course and it was fun to do. It is made from 01 tool steel with brass bolster and mahogany handle. It earned me £50 and is now the property of Sheffield Uni. The blade was ground and tempered and the spring was made of the same steel, quite an interesting project.

 

[Bsmith]

BS.
How do you harden the blade ?
For by what you have said you normalize the steel and then temper it.
I was always under the impression that what we did was to harden to dark blue , quench then reheat temper to straw & quench .
This would give the tool toughness without brittleness but still have great hardness & durability .

If you only straw heat the edge of the blade from the cutting edge backwards into the blade body you will not have the high quality heat treatment running out from the blade back, it will be just a limited tempering which to my reckoning will be be liable to breaking off and/ or chipping along the cutting edge.

For our cutting tools made from HC steel to pass muster as hardened and tempered tools they had to be hammered cutting edge first in to the base of the anvil which is wrought iron with a 2.5 lb. engineers ball pene hammer , any rubbish tool would blunt or snap .

.

Heating only the edge of the blade means that as you sharpen it back it gets softer, so by the time its first sharpened it is pretty close to correct temper, but like you say this edge only does for a few sharpens then it gets too soft and needs re-tempering. Your way of an all hard blade is much better, thank you for parting with that info.
The way I was taught to sharpen/temper a cold chisel by the blacksmith,,, Check the hammer end first to see if its curled or broken to identify whether hard or soft HC steel. Heat the business end to cherry and draw out to shape on the anvil with hammer. Leave to cool. Grind cutting edge. Heat about half inch of cutting edge to cherry and dip half inch in water a few times until cherry turns just blackish, quickly clean by scraping on concrete floor and watch, the half inch will turn straw colour then you will see blue creep to the cutting edge. When the blue reaches the cutting edge quench for normal HC steel. If its a soft chisel, quench slightly before blue reaches cutting edge, if hard then delay slightly with quench. Yes, we always tryed them out on the anvil base too, lol.

 

[syborg]

funny you should mention this,
since i broke my penknife im in the process of making one,

i used an old dull file.

i built a forge first. then tossed in the file "minus the handle".

heated till cherry red then quenched in oil.

its now quite springy which is what i wanted.

then set about it with a 60 grit disc, then an 85 and then 180 and 240 grit emery. then used scotch brite then finaly a chrome vanadium screwdriver to bring up a shine, the pics here are just the primary grinding stage, i,ll add more pics later.

peace

syborg.

 

[Welderpaul]

then finaly a chrome vanadium screwdriver to bring up a shine

How does that work?

 

[Pete.]

Works by burnishing I presume?

 

[mr migwire]

details on how you made your forge please syborg.

ive been looking at doing a homemade one but dont know where to start.

 

[pedrobedro]

After you anneal it and shape the blade it needs heating back up to cherry red when it becomes non magnetic (test it with a magnet) then quenching. before you grind it and sharpen but don't get it too hot in the process of grinding. Then it needs tempering to it's final state and leaving to cool gradually. Look for Greenpete videos on google, he shows the process.