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Repurposing a blunt file?

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disco_monkey79

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As per the title, my standard "go-to" file has finally become blunt to the point of uselessness. And it only lasted 25 years - modern rubbish! :)

I know some people grind files in to turning tools, but this one is a bit small (and a half-round type) EDIT - as mentioned below, file steel is brittle, so I DO NOT recommend doing this!

Any other bright ideas for what it could become, before it ends up in the recycling?

Ta
 
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MikeG.

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It's rumoured that Jim Bowie had his famous knife forged from an old file. So if there's anyone you know who needs disemboweling...... :)
 

disco_monkey79

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Ha! As this is a public forum, I am going to answer "no" - you can decide whether to believe me or not...!

I do like the idea of turning it in to a knife though - thanks!
 

Eshmiel

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There are various bits of info about the interweb about how to chemically sharpen metal files. As I recall, you dip them in some kind of weak acid for a length of time - until the acid eats enough metal from each blunt serration such that it again comes to a point.

Eshmiel
 

Sheffield Tony

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Does this acid trick really work ? It sounds like wishful thinking to me. I would have thought it more likely to remove sharp edges than otherwise. Some of the metalwork we have made has an acid etch to reduce machining marks. But maybe intuition doesn't apply here. Does anyone actually do it ?
 

AES

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@Eshmiel: There are various bits of info about the interweb about how to chemically sharpen metal files. As I recall, you dip them in some kind of weak acid for a length of time - until the acid eats enough metal from each blunt serration such that it again comes to a point.

AES: Yup, there are various such pieces of info to find. I've not tried myself, but I suspect that in the case of file worn as much as Disco_Monkey 79's (the OP), the results are very unlikely to be successful. Any type of acid treatment can "only" take away from what's already there (be it general crud, or, to a small extent, the base metal). Acid cannot "add" anything, especially not new, "pointed" teeth IMO, so if the OP's file really is as worn as he says, then I suspect it's finished - as a file. But I haven't ever tried this method myself, and apparently, there's at least one company in the US that does do this. But again, I can't myself see that acid can add to what is really already missing.

I have a couple of very old worn files which my Dad (died 1977) turned into bearing, etc scrapers when he was working, and very effect they are too, even today. Though the number of times I actually need a scraper are very few and far between these days (scraping in new white metal bearings for your Ford 100E crankshaft has gone out of fashion you know)!! :) Though there ARE other uses for metal scrapers - sometimes.

Apart from scrapers (metal), I know of no other "certain" uses for old files. But there have been posts here in the past about "turning" them into wood turners tools (sorry for the pun)! Some say it should work, others think "too brittle". I'm not a wood turner myself so I just dunno, sorry.

But IF he's still around, member CHJ not only has a very good engineering (metal) apprenticeship background but is also a very accomplished wood turner. If he doesn't pop up here soon I suggest PM-ing him (sorry, "conversation"-ing) him.

HTH

Edit for P.S. Clearly my post (above) has crossed with a couple of others. Myself I just do not know if files turned into turning tools are too brittle or not, sorry. What I can definitely say is that files (good ones anyway) are about the hardest bits of metal you're ever likely to find in the average workshop. Hardness does of course also mean "brittle" but if that brittleness equals a definite safety hazard in the wood turning use I just do not know, sorry.
 
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disco_monkey79

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files are far too brittle.
I know that you are not proposing to do this, but for anyone considering it, just don’t!!
Excellent point to mention, I have edited my original post accordingly! Thanks
 

MikeG.

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Does this acid trick really work ? It sounds like wishful thinking to me. I would have thought it more likely to remove sharp edges than otherwise. Some of the metalwork we have made has an acid etch to reduce machining marks. But maybe intuition doesn't apply here. Does anyone actually do it ?
It works, but not in the way claimed. What it actually does is remove grime and surface rust, properly exposing the (otherwise unchanged) teeth to the work for the first time in yonks. It's well worth doing, and the effect is the same as if the teeth had been sharpened...but they haven't been.
 

clogs

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they, the files have to be softend by heat.....get em cherry red and alowed to cool slowly in air.....
grind whats left of the teeth away, so smooth....now u can grind the end how u want say for a scraper....
or re heat to cherry and reshape say to a bowl gauge......then shape the cutting end close to the cutting edge profile u want.......
now u want the steel hardend back to hold it's edge.....
so now heat about 3-4 inches up from the cutting tip, alowing the heat to creep up to the edge till it is almost cherry and then quench in oil...old eng oil is OK.....
now ur suposed to heat up to around 400deg, cherry being 8-900.... in and oven and let it cool down slowly....this to anneal the steel.....it will change the grain pattern of the steel.....
now I dont have an overn for that job......
so for me just an oil quench has served me OK......
I will add that my first turning tools were made this way but now long gone.....
I have made and inherited several cold chisels made this way and they are excellent.....
But tools are now so cheap in comparison to when I was a lad 50 years ago.....
so why bother....and if u went the top of the range tools like Sorby for comparison they wont be as good.....
if u went to places in Asia, out in the sticks they'll still be using this method for tool making..
 

clogs

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oh, and the acid trick doesn't really work on old files.....might help a file thats just starting to go off tho....
again, why bother when decent stuff don't cost that much....
 

Eshmiel

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Personally I've never tried sharpening a file with the acid since I keep mine very clean (with a stiff-haired paint brush) and only use them on wood, so they stay sharp.

However, despite some rather definite denials above, along the lines of "acid only removes rust & gunk", there are both products and experiments about the interweb that claim to put back a sharp edge on the file serrations which have gone blunt i' their tips through use. The proposal is that an acid can eat metal from the front and back faces that meet at an edge until the edge goes pointy again. It's said to work only when a file has already been cleaned of gunk and rust with a copper scraper, bath in a degreaser and so forth. So the acid isn't just removing gunk from a file that's still sharp. .... It says.

This sounds possible but unlikely. Why does the acid not also eat at the blunt edges making them even blunter?

What's needed is the sort of experiment that DW did with his unicorn sharpening, showing the before and after with a powerful microscope and comparing the performance of blunt files that have been "acid etched" with those that have just been thoroughly cleaned of rust and gunk by methods that don't dissolve metal.

In all events, if metal is dissolved, this is surely going to produce relatively weak edges that won't last too long, even if they have been made more pointy. Yet there are products available (in the USA, which is always something to be wary of since they're so good at the snake oils) that claim to be able to resharpen a file "4 or 5 times" using this acid etching process. .....

Another queer little alley of woodworking that those with an insatiable curiosity can go down. :)

Eshmiel
 

Inspector

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There is a company in the US that uses a very fine abrasive blasting process to sharpen files and rasps. They have been doing it since 1932. I don’t know it’ll there is a British or European company doing the same.


If you can do rudimentary heat treating and forging you could rework the file into a carving gouge. As for making it into a tool without heat treating the scraper has already been suggested and I think a marking knife would work too. Both don’t get impact or, if used properly, bending forces so wouldn’t break like a turning tool could. On that I will say my father used some files and a farrier’s rasp as turning tools without ever breaking one.

Pete
 

MikeG.

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...........despite some rather definite denials above, along the lines of "acid only removes rust & gunk", there are both products and experiments about the interweb that claim to put back a sharp edge on the file serrations which have gone blunt......
That's the same internet where you can read eye witness accounts of encounters with aliens, bigfoot and Nessie. Approach stuff you read on the internet, including this, with caution. It's a bit of a mugs game to trade off one "heard it on the internet" notion against another. I picked out the salient word for you.
 

TheTiddles

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Some surgical scalpels are made by chemical etching from two sides of a panel, the resulting edge is extremely sharp, however it’s rather more than a dunk, the people who know the process are rather proud of it

Aidan
 

rxh

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I tried to sharpen some old files with acid but I noticed no improvement, much to my disappointment.
 

Alpha-Dave

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Some surgical scalpels are made by chemical etching from two sides of a panel, the resulting edge is extremely sharp, however it’s rather more than a dunk, the people who know the process are rather proud of it

Aidan
The Microplane tools are made with etching through a thin sheet. Not a simple process.

 

Eshmiel

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That's the same internet where you can read eye witness accounts of encounters with aliens, bigfoot and Nessie. Approach stuff you read on the internet, including this, with caution. It's a bit of a mugs game to trade off one "heard it on the internet" notion against another. I picked out the salient word for you.
Mr G,

As you know everything about everything, in a most certain fashion, I believe you should publish it all here in a Very Long Thread. But hang on! You too are "of the internet" and so, by your own definition must be expressing Bigfooted alien Nessie stuff ... as must we all!!

Wot a conundrum. We would all like to offer our wee bits and pieces to others but MikeG has decreed that, since its on the internet, it must be wrong. Well, unless it's a MikeG pronouncement. .....

Somewhere there is a small fault in this logic.

****
Meanwhile, someone may happen along who actually knows something about it. You know, from experience rather than some dismissive prejudice offered in the reedy-voiced tone of an auld schoolmarm. :)
 

AndyT

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There's a long tradition of making tools from old files. Here's one that I own - I'm not skilful enough with metal to have made it, but I can confirm that it works.
IMG_20200910_222145710.jpg


IMG_20200910_222233937.jpg
 
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