It you Google this heading, you'll see posts that show how these tools can be sharpened by soaking them in vinegar. I tried it with some worn cabinet-makers rasps, and it actually works. These tools cost $50-$60 each, and so it really pays to get more mileage from them.

Hi--how long did you soak them ??
Thanks Sydney

I put them in a piece of PVC standing vertically for four hours.You need to rinse them thoroughly with a solution of baking soda afterwards otherwise they'll rust quickly. I might experiment with laundry bleach next. I think anything that oxidizes might work. Bleach would probably work a lot faster.

I think what you're looking for is an acid, check the PH of bleach. You may be trying to remove steel in this process, not convert it to something else. If you want something more agressive, you could try plain old pool acid.

I've done it a few time over the years, but mainly on garage sale finds. I think you can get some more use out of a rasp or file, but careful with metal files intended for a good finish.

Search Boggs tool and file sharpening service. For the non DIY.

you should always clean your files and checkering tools with a brass wire brush not steel.

I've used Boggs Tools & File Sharpening for many years.
They do an excellent job, very inexpensivly and are a quick turn around.

The end results are amazing. Even those files you send in that they consider less than acceptable after sharpening (and cost you nothing) are still sharp and usable.
Those 'rejects' are returned with the tang colored in a red dye.

They resharpen drill bits, mill cutters ect also.

Wrap up the files by rolling them up in newspaper so they don't touch each other. Put a note in with the number of pieces and contact info. Pack securely in a USPO flat rate box.
They usually call and let you know the cost.
Sometimes they just ship w/a bill after you've done business with them a time or two.

https://boggstool.com/
Go to the 'Divisions' section and click on 'File Division'
In there is gives some of the prices for various shapes and lengths of files for both sharpening and for buying new (they sell new files also)

I've tried the acid sharpening process before,,this is like getting a new file back.

I helped the widow of a late American gunsmith clean out his shop. One of the things I sold for her was a gallon( or half gallon) of a commercial file sharpening solution. As this was about 1983-4, I don't remember the product name.
Gunny,
I have two commercial " file cards", both have short steel bristles( one has fiber bristle brush on the other side). The "trick" is to brush along the rows of teeth, not against them. To clean "pins" that are not dislodged by the card, I use the flattened neck of a cartridge case. Rarely, I have to resort to a scribe. The "trick" for all this is to go along the rows of teeth, not against them.
Mike

Vinegar that is a new twist for file re sharpening. The traditional method of dip sharpening over here has always been Lead Acid Battery Acid, to move things along a little quicker a slightly stronger mix of Sulphuric Acid 35% Acid 65% de mineralised water. Another apprentice job for me in past times it did take me some time to work out how I got the holes in my work clothes after they where washed. The files where left overnight in the Acid then rinsed in water then left for a couple of hours in washing soda to neutralise any Acid residue. Sharpening files is a sort of long gone practice because the cost of new files today is a fraction in real terms than in the past, Now it is just use cutting tools until the edge has gone them throw them away this culture has come in rather than re sharpen in modern engineering.

I think one of the possible problems with many modern files is that they’re case hardened, so the acid quickly cuts through the hard stuff and the remaining steel is recycled mild.

Would someone explain to me how acid actually sharpens the edges in the rows of cutters on a file? How does it not eat away at all the exposed steel the same amount?

Thanks, SRH

Stan, I don't know how it works, but I'd guess that the blunted portion of the teeth is etched more than the edges that remain sharp because they offer a larger area for the acid to act on. I hope someone else can offer a proper explanation.

Stan, my understanding is that it does eat away at all the steel. The original cutting edge become smoother and wider as the rasp or file wears. I don't believe an acid bath can do a controlled sharpening, but I think there's more surface area on the bevels, for the acid to attack, than on the dull edge. So, somewhat of a point starts to reform, as well as an overall rougher texture.

I believe the important part is that it has to be a quality high carbon steel file that is through hardened, so that any steel that's uncovered is also hardened. The thing that I've noticed is that sometimes there're a few random coarser teeth that leave scratches that the same file might have done a bit better job at if new. I suspect it's less of a thought if the tool is intended for wood work. Just opinion, that's all.

Thanks, craig.

SRH

I just sent off a 49 and a 50 Nicholson usa made rasps to Boggs tool for sharpening. Looking forward to seeing the results.

I also bought a 50 Liogier rasp for SDH and am quite pleased with how it cuts, very sharp and a nice smooth finish.

I usually clean my files with a file brush and I've found sometimes it helps to lightly heat them with a torch while brushing.

Thumbs up for Boggs tool, both rasps sharpened and returned to me for less than 25$.

Good report, Steve. Have you any idea how they do it? Is it by mechanical cutting, or by acid etch?

This from the Boggs Tool website:

"We sharpen files, rasps and key cutters using (liquid honing) abrasives driven by steam pressure.

The abrasive blast removes metal from the backsides of the teeth until the edge is reformed. We

make these edges very sharp.



All files are sharpened first, then block-tested and inspected. If they fail, they are marked red.

This means they cannot be sharpened again so please do not send them back to us. These

(rejected) files are vastly improved and will still give you plenty of use.



Rust is not a problem. We can remove most, if not all, of the rust depending on where it is at.

Some brand-new files are not as sharp as they can be when first purchased. We sharpen new files

as well."



I sent them a #49 and a #50 American made Nicholson rasps, fast turn around, sharp and what I felt was deal price wise.

I have had a chance to do some shaping with the Liogier rasp purchased from SDH, that is a superb tool and one that will be with me for years to come. Next up will be one of the smaller 1/2 round rasps he sells for detailing work.

Thanks, Steve. I've got several very large mill bastard files that are worn badly. May send them a couple to see what they charge.

prices:

https://boggstool.com/file-department

Thanks, Steve.

Sent several rasps and files to Boggs for resharpening and have been well pleased with the results.