old files

[lurker]

I know its been discussed but I cant find it.
I'm looking for methods to rejuvenate a few old metalworking files and some heavy duty rasps.

 

[Bm101]

Acid cleaning works a bit Lurker. I did all my old second hand boot salers and it definitely works to an extent.
I use citric acid rather than vinegar because it's cheaper, easy to store, far less space, smells a bit better, and you can change the concentration and it comes in the post from Amazon. I sometimes add a drop of fairy liquid because I read you should to break surface tension. Quite often I don't remember and not sure it's that vital tbh.
This is the method I have adopted for the process generally.
Clean physically. File card them then degrease properly.
Soak the files. Keep an eye on them.
I've started brass wire brushing (drill type) everything that I dip once it comes out the tank.
I wash sodium bicarb water paste over and ideally stick in the oven to properly dry out.
The last step is a bit theoretical. But I've had stuff flash rust but never when I've done it so I just do it now. Hardly makes a difference for the amount I do.
Been busy lately though. :wink:
https://imgur.com/a/ITSHywI

Cheers
Chris

 

[sunnybob]

Old rasps?
with a bit of hot forging, they sir, will cut! :shock: =D> =D> =D>

 

[Inspector]

There are companies on this side that use a liquid abrasive honing process to sharpen files. They test them afterwards and only charge for the ones that pass the test. https://boggstool.com You get back all you sent them with the poor ones having the tang painted red. Perhaps there is a similar company on your side. You could contact Boggs and see if they know someone.

Pete

 

[ED65]

I know its been discussed but I cant find it.

There likely are earlier ones but the discussion I remember wasn't in a thread on this subject like I'd thought so I had difficulty locating it, it's a tangent to a thread on another topic, forming-chisel-side-bevels-t112905.html

The process I use is basically what Chris describes above, but with some key differences.

Just to reiterate the important aspects, it is vital to thoroughly clean and degrease to begin with. Very dirty and greasy files can benefit from a soak in caustic soda for this purpose. This will incidentally remove any aluminium pinning, which is a godsend as it's a right PITA to deal with otherwise. (Wish I'd known this tip earlier as I've manually picked over more than a dozen files clogged with ali and you lose the will to live eventually.) Wear PPE and take all due care and attention if using caustic.

Then you soak in acid, if necessary with periodic scrubbings to clean off the surface, just like when de-rusting. Soak time depends on acid strength, the cut of the file and how dull it was to begin with. Coarse files and rasps can take a long time (a week +) in weaker acids.

When you feel the acid has done enough you clean well and then dry quickly to help minimise flash rust.

I've intentionally left out any mention of neutralising the acid residue in a solution of bicarb or washing soda above. Because A) it doesn't reliably prevent flash rusting and B) what concentration and soak time should you use to counteract the exact pH of the acid you're using? Nobody can tell, and you don't need to know anyway.

Instead, scrub well with common hand soap and a firm toothbrush. Quite apart from this being far more effective at reducing post-acid rusting in my direct comparisons, I'm often amazed at how much extra residue this gets off the surface even if you thought you'd scrubbed really thoroughly with a fine wire brush.

Two more tips, if you use vinegar or citric acid if you add salt it'll work better. And at any stage of the process don't use a wire wheel; this is especially important after sharpening, you'll noticeably dull them.

 

[Inspector]

Well another tangent about to happen. ED65 you mentioned using caustic soda to remove the aluminium in the file. I have a carbide saw blade loaded with aluminium to the point of filling the gullets. Will the caustic soda remove the aluminium without damage to the carbide or the brazing holding the carbide?
Thanks
Pete

 

[ED65]

I have read some concerns about using cleaning agents that contain caustic soda (Fairy Power Spray and its equivalents for example) for cleaning TCT saw blades. I think you're safe with the carbide but the brazing is an open question. It could vary from make to make and the reaction with a strong alkaline is an unknown, so many are of the opinion that it's safest not to take the risk. Worth Googling for more on this though.

Just in case it isn't mentioned in anything you find and identifying the blade later on is important, soaking in caustic is pretty likely to remove any printed info as it's a very effective finish stripper.