It's not rocket surgery to sharpen files and, rasps. Some sulfuric acid (liquid drain cleaner) and water is all you need. I use a 10 to 1 water to acid mix. You'll need a tube like container. A length of pvc pipe (with end cap) works well. Size the pipe to fit the file/rasp. Measure out and pour the water in the pipe. Always add acids to water, not water to acid. Add the measured amt of acid. Drop in the file/rasp and wait an hour or so. Take it out and bathe it in  strong solution of baking soda and water to neutralize the acid. Use the wife's hair dryer to dry it.

20 hours ago, p_toad said:

Those Nicholson "thingies" were listed on Amazon back in 2013 and there are zero comments.   If they are made of the same steel and heat treating as their current files (hardened to old solder RC, I'm guessing)...all i have to say is "no thanks...ever"

I'm not a metallurgy expert, but I'm thinking you need a different alloy / heat treatment for chisel edges than for rasps/files.

 

I'm thinking those contraptions are for Joe Garage that does something with wood every couple of years.

 

And I remembered the name of the service. I sent a bunch to them. They told me they could make a Nicholson patternmaker's rasp #49 sharper than new.   If they can't be sharpened, they will either trash them or return them to you.   http://www.boggstool.com/