Forgive this long post. There's several threads on files lately, and they coincide with my somewhat recent interest in files as well. Here's some of what I've learned through browsing company catalogs, machinist sites, woodworking sites, and then from my own experience with recent file buying binges.
vixen / curved tooth mill files, super shear files, Iwasaki carving files
The most aggressive type of file for metal that I know of are vixen files, or sometimes called curved tooth mill files. It's used in the auto body and aircraft making industry. Cuts very aggressively but leaves a smooth cut. There are variants in its design. It comes either somewhat flexible so that fits on sort of a curved cradle handle and used on large surfaces almost like the way a woodworker would use a hand plane. There are also more conventional ones shaped like what we're used to in flat or half-round files. They work great on wood as well. Several manufacturers make them. I have an old new stock labeled Sandvik, I know Nicholson and Simonds also made them. I don't know how the newer Brazil made Nicholsons or newer Honduras made Simonds compare to the older USA made ones because I've just been making the effort to get nos USA Nicholsons or Simonds (among other brands) during my recent buyings.
Among the variants of the vixen file design, there's a version where the there are chip breaker grooves cut into the milled curved teeth. Those chip breakers are used to clear out metal filings from the teeth more easily, and you'll see that idea used again on other file types made for metal removal. Nicholson calls theirs Super Shear Cut file. The curved teeth on these are also offset at an angle. Meaning it looks like you're looking at the arcs from a quarter of a circle, whereas in the regular vixen files you're looking at more like semicircular arcs. I think that offset angle causes that shearing effect that Nicholson named theirs after.
The Japanese have a version of the curved tooth mill file with chipbreakers in their Iwasaki carving files. These are probably the most aggressive files you can get. I only know of woodworkers using them though, and they rave about them. Their super fine cut can remove wood faster than a rasp yet leave a surface as fine as a second or smooth cut file. I have the super fine in the smallest size, and it does cut wood very aggressively and you have to use a light touch and basically shave off wood. I can't imagine what their coarse teeth would be like. The wood workers I've read who've commented on them only need to go up to their medium cut and say that it's plenty of wood removal for them. I don't know how well they'd cut metal, but they claim that their files have harder teeth than any known file. But maybe the aggressive teeth isn't good on metal in the same way that you wouldn't want to cut metal with a saw with big teeth. They do work on wood like a dream. So if you want to shape your handles, I would recommend getting their smallest and finest cut files to start out.
Due to the curved design of the teeth of these types of files, I don't think they would work for draw filing because you won't be cutting at the correct angle. I haven't used them on metal at all because I love these files so much that I don't want to risk damaging them if I mistakenly use them on ferrous metal when they're built for softer metal and wood. Like I said, they were designed for auto body and aircraft building, and in the case of the Iwasaki quick wood removal. If anyone gets one of these and tries it on steel, please do let us know how they work out.
I have a 10" nos Nicholson Super Shear, an 8" Sandvik Multifile (almost identical to the Nicholson Super Shear), a 12" nos half Sandvik half-round vixen file, and Iwasaki carving files in 110 mm Extreme-fine cut half round as well as flat. I love all of these.
Magicut, Multicut, and Chipbreaker files
The next class of files for metal have more traditional straight diagonally cut teeth. They're all single cut files (which apparently work better for metal than double cut teeth). They all have chip breaker grooves cut at intervals to help remove metal filings from the teeth (but chalking the file is still a good idea).
Nicholson's Magicut has the chipbreaker grooves set closely together and at the same angle, so it ends up looking like a very rough double cut file. But it's actually a single cut file with lots of chipbreakers.
Samuraistuart mentioned he has a Simonds Multi Kut (or Multicut or Multi-cut, depending on the listing), which is of the same idea, but the chipbreaker grooves are cut in a diamond pattern so have a very distinctive easily recognized look. Pferd and Grobet call theirs Chipbreaker files and they have the diamond shaped pattern chipbreaker grooves like the Simonds.
I have a 12" nos Nicholson Magicut, two 12" new stock Pferd Chipbreakers (one of which I ground the sides smooth to make into safe edges).
These types of files feel a lot sharper and more aggressive than the traditional bastard files that we're used to. But they're not as aggressive as the curved tooth mill files. I haven't had that much time using them yet. From my guess they'd work great at shaping the profile of a knife and also roughing the bevels.
Long Angle Lathe Files
As their name suggests, they were designed with people who file while the stock is turning on a lathe. They're all single cut and come in coarseness from bastard to smooth. But because of the higher angle that the teeth are cut at, they end up working really well for us in draw filing.
When you're filing in a conventional stroke pushing the head of the file forward and handle of file trailing, theoretically it would be the most efficient if the teeth of the file is perpendicular to the surface being cut. Most conventional files that we're used to, whether single cut or double cut, have their cutting teething set at 30 degrees. I'm not sure on why 30 degrees, probably to get shearing action in and also to reduce chatter. When we turn the file 90 degrees to do draw filing, those teeth end up being now 120 degrees (or 60 degrees depending on how you look at it) to the stroke. This makes it less perpendicular and more parallel to the stroke, which reduces cutting efficiency.
The long angle lathe files have teeth at 45 degrees. When you turn the file 90 degrees to do draw filing, the teeth are still at 45 degrees to the stroke. So they work much better for draw filing than conventional files.
Plus their sides are already safe edged so you can better use them to file the knife's shoulders.
Important: If you're going to draw file and pull the file toward you, be sure to hold the handle in your left hand and the head in your right. If you're going to draw file by pushing the file away from you, then hold the handle in your right hand and the head in your left. Holding the handle in the correct hand positions the teeth of the file to cut. Otherwise you'd be dragging the back of the teeth's cut against the blade blank, which not only would not cut anything but also dull your file's teeth.
I have a 12" nos Nicholson bastard cut, a 10" second cut Grobet-USA (which is crappy, more on this later), and a 10" second cut Mercer (bought at Uncle Al's in 2006). I love the nos USA Nicholson.
The rest
There's a ton of different shapes out there that have less specialized teeth than the ones I mentioned above. Things like half-rounds, mill files, hand files, triangle files (more commonly called 3 square), round files, square files, etc. come in single cut or double cut, with roughness from bastard to second to smooth, or they can follow Swiss pattern cuts which go in roughness from 00 - 0 -1 - 2 - 3 etc up to 6 for the smoothest. These you just choose the shape, size, and roughness you want. These are the files that we're more used to, being available in hardware stores or easily found.
BRANDS
This is what I've found from reading other people's experiences and some from my own. In short, these days if you want the highest chance of quality you either have to pay up by buying Swiss made Grobet (make sure it's Swiss made), or some harder to find German made files (not any better than the Swiss Grobet anyway), or use some effort to track down older American made files (particularly Nicholson).
The older American made ones can probably be found easiest through eBay, since most local hardware stores have probably already sold out of their American made stock unless you have a real small store tucked away somewhere unknown. Search eBay for "nos" files, which stands for "new old stock" files. Other good nos American brands to look for are Simonds, Heller, Disston. Don't just take the auction description at their word though, because nos to some sellers may just mean something that's been sitting around for 2 years, which would include some of these Mexican or south American made Nicholsons, or Honduras made Simonds, which I don't trust. And don't trust a stock photo showing a Made in USA stamp either, because the seller could just be lazy and put up a stock photo thinking that all files are the same. Not that he's scamming you, just that it doesn't occur to him that it's important to you where it was made due to quality concerns. So ask the seller to check the stamping on the file that he is selling and will be sending that it's stamped Made in USA if you're buying a nos American made.
Rant on Grobet-USA. This was a real downer for me. Grobet is a reputable company, considered by many to be the best file makers in the world. They have a USA division. That combination gave me assurance and I fairly recently bought 4 new Grobet-USA files from a reputable supplier. They were very disappointing. One was a small bastard cut square file that is just plain dull and hardly cut. Another, a 10" long angle lathe, is warped out near the head. The other two, half round files at 8" and 6" second cuts, aren't as good as a couple of old, made in India half round files I bought back in the early 80s when I wasn't concerned about quality and just bought the cheapest files I found at the cheapest hardware store. I don't know if this is a recent Grobet-USA thing or not. I've seen photos of Grobet-USA files where the Grobet-USA is stamped on the file. The ones I got the logo was sloppily stencil etched. Seeing how there doesn't seem to be any made in America file companies anymore, I wouldn't doubt that Grobet-USA has also shipped theirs south of the border to be made. There is no country of manufacture stamp or etching on the ones I bought. I also wouldn't be surprised if back in the day Grobet licensed their name to a reputable American company to represent them in the US market. Like I could easily see Nicholson making their files and stamping it Grobet-USA back in the day. But now, either I got 4 out of 4 bad ones, or the company that has the license to the Grobet-USA name has also shipped the work outside the US without regard to keeping quality up. I would not recommend new Grobet-USA files. Swiss made Grobet though, I have several needle files of, and they are superb. I would not hesitate to buy Swiss made Grobet.
India made brands. The ones I have are surprisingly good files. Like I said just above, the two I have from India that I bought for $2 each back in the 80s have held up very well. As a matter of fact, I would say that my India made 10" bastard half-round is sharper and more aggressive than the coarser nos 14" bastard half-round Simonds Nucut made in USA that I bought on eBay. That made in India file is stamped Aces. I have a smaller bastard half-round made by JK Tools in India, which I recently learned makes more files than anyone in the world.
Warrensville and Mercer Tools, two smaller American companies who've been making files for at least a couple of decades, have their files made in India. I have some nos India made Warrensville needle files that I recently bought on eBay to try out, and they work quite well. And as mentioned previously in the post I have a 10" long angle lathe file from Mercer Tools that I bought at Uncle Al's in 2006 which is pretty good (better than the recent Grobet-USA one). So maybe India made files are a good option if you're having trouble finding nos USA made or don't want to shell out the bucks for Swiss made Grobet.
