How to sharpen dull files

[Timberwolf]

and rasps.....

https://www.youtube.com/watch?v=rRakH7TrE2E&t=11s

[Bill Holt]

That is cool.  I wonder if that is how Boggs Tool sharpens files and rasp?  Several years Boggs was recommended here.  I boxed up about 18 and they came back sharper and better than a new one.  The pricing was crazy cheap.  I was so impressed I called the place.  Mr. Boggs answered the phone and was a delight to visit with...especially about the NBA.

[Timberwolf]

That is cool.  I wonder if that is how Boggs Tool sharpens files and rasp?  Several years Boggs was recommended here.  I boxed up about 18 and they came back sharper and better than a new one.  The pricing was crazy cheap.  I was so impressed I called the place.  Mr. Boggs answered the phone and was a delight to visit with...especially about the NBA.

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I don't know for sure how it's done at Boggs but have an idea that he uses electrolysis in some manner...I do think the acid etching method would work also, but may need to be submerged longer than one hour,. Ferric chloride could also be used...and may work faster than ordinary household sulfuric acid. I have used it to etch Damascus steel.

[AHill]

I've never, ever heard of the theory that "steel sharpens steel" when it comes to files and rasps. From Day 1, I always have kept my files and rasps protected, so that they maintain sharpness. I also use a bristle brush to clean my files and rasps. The metal bristles on file cards just doesn't seem right to me. I would never try to use brass on a rasp. Too much danger in bending the tips of the rasp teeth. You can accomplish the same thing with vinegar. All you really need is some sort of weak acid solution that can attack steel. Acetic acid in vinegar works just fine. It's probably cheaper than drain opener anyway.

There's a limit to how many times a file (or rasp) can be sharpened with acid. At some point, the acid will round over the ridges / teeth, rendering the file / rasp no longer viable. Also, if you start with a quality file and/or rasp, the process works better. Older, Made In the USA files had more crisp machining. Slav (former WN member) sold NOS files and rasps at reasonable prices. If you ever try the NOS ones, you'll realize all files are not created equal.

Boggs uses a combination of acids and laser etching.

[Tony Z]

It has been at least about a half dozen since I sent files to Boggs, but at that time, I think I sent twenty or thirty years worth! Still have at least a dozen still wrapped in the newspaper he returned files in!

Anyhow some tips for newbies around (mostly for files): first never let steel go against steel. Second, only use your files on same material: use same files on steel, others on aluminum and so forth. Finally, learn to chaulk your files, so they don't load up. I'm not certain about the wisdom of a fiber brush to clean teeth, as I don't see how a brass brush dulls teeth (I'm not above cleaning packed in wood out with a QUICK pass over a flame).

[AHill]

It has been at least about a half dozen since I sent files to Boggs, but at that time, I think I sent twenty or thirty years worth!  Still have at least a dozen still wrapped in the newspaper he returned files in!

Anyhow some tips for newbies around (mostly for files):  first never let steel go against steel.  Second, only use your files on same material:  use same files on steel, others on aluminum and so forth.  Finally, learn to chaulk your files, so they don't load up.  I'm not certain about the wisdom of a fiber brush to clean teeth, as I don't see how a brass brush dulls teeth (I'm not above cleaning packed in wood out with a QUICK pass over a flame).

My comment about brass relates to rasps, not to files.  Rasp teeth narrow down to a very fine an sharp tip.  Depending on how much force you use, hunk of brass could bend those points, rendering your rasp less effective.  Joel Moskowitz from Tools for Working Wood was the one I first heard recommending using a bristle brush vs. the metal file card.  It works for me.  Auriou recommends not using wire brushes to clean their rasps.  Liogier actually sells a brass brush to clean their rasps.  Personally, I'd opt for the least aggressive method.  Good quality rasps are expensive, and I want them to last as long as possible.

One other method to remove clogged wood from a rasp is to soak the tool in hot water for a few seconds.  The water swells the wood, which will pop out of the pocket.  Brush off the wood and dry the tool.

[Timberwolf]

My comment about brass relates to rasps, not to files.  Rasp teeth narrow down to a very fine an sharp tip.  Depending on how much force you use, hunk of brass could bend those points, rendering your rasp less effective.  Joel Moskowitz from Tools for Working Wood was the one I first heard recommending using a bristle brush vs. the metal file card.  It works for me.  Auriou recommends not using wire brushes to clean their rasps.  Liogier actually sells a brass brush to clean their rasps.  Personally, I'd opt for the least aggressive method.  Good quality rasps are expensive, and I want them to last as long as possible.

One other method to remove clogged wood from a rasp is to soak the tool in hot water for a few seconds.  The water swells the wood, which will pop out of the pocket.  Brush off the wood and dry the tool.

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A person with half a brain knows better than to let files rub against one another..annealed copper or brass works fine to push the swarf out of the teeth, but a sharp pointed steel push-pin { like an ice pick } works really well for the files loaded deeply with steel swarf...Any acid will work but a strong acid works faster. And using the file as an anode will also work.,,Chalking a file is an old machinist's trick to retard pinning and the teeth getting loaded with swarf..Learning how to "lift" a file off the work on the return stroke helps to keep the teeth sharper.

[Pedder]

And please use a handle on every file. Everytime.