I was taught both ways by two different people. I have to admit that I always thought that the "lift-on-the-backstroke" method was best, as it just seemed to me that it would result in less dulling of teeth. But I've certainly done it both ways - usually dictated by how big a hurry I was in and how frustrated I was at the moment. I did note years ago that when filing aluminum and other soft materials, keeping some contact on the backstroke did keep the file cleaner - and even removed a bit more material. And I always figured that soft metal was not going to dull the teeth of a hard metal file. But after watching this, I may try to watch the effects of both methods on my own projects to see if the test results look reasonable in real-world use. Pretty sure, though, that I'm not gonna hold a toothbrush on my work the next time I'm deleting some material, smoothing out a rough edge, or rounding off a sharp corner. It's an interesting question - which may mean that if I really find this interesting, my life may be a lot duller than my files, eh? 😁
Never called myself a machinist, but I spent some time in the early 80s as a machine operator. Basic task? Cutoff saw. Drilling and tapping was a step up! You do learn how to *not* break a tap after a while:-)
Here's a way to tap without making chips.
And pair that with a Flowdrill and you have a awesome way to make treads in thin materials. https://www.flowdrill.com/usa_en/
@Lee - those are some interesting tools, and I've never seen nor heard of them before. Thanks for providing the links - I'm intrigued enough to do some more investigating. If anyone else has experience with these technologies, let us know! 🙂
"There is a 50 percent chance you've been filing wrong" made you think it was about adjustable wrenches? Hmmm. I actually would have guessed maybe it was about arranging your folders alphabetically versus chronologically... 😋
My favorite file is a die grinder. I find files more useful for deburring than for removing material. When I do file, I use the back and forth method. The more important tip is to attack the material at an angle instead of straight on.
Back in about 1974, I was taking a test drive with a safety manager in hopes of hiring on with a company as a long-haul driver. I'd had a couple of years' experience, and figured it'd be a snap. I was pulling an empty trailer, and he was telling me what to do - putting me through the paces, so-to-speak. We were about 5 minutes into what he'd said was to be a half-hour test. When he told me to exit the freeway, I downshifted the 13-speed through several gears while slowing down on the off ramp, then applied just enough brakes to stop at the end. He chewed me out and said that was all wrong. "Use only your brakes", he said, "transmissions are expensive to replace, but brakes are cheap". I said, "I'd rather save my brakes than my transmission." He laughed and said, "That's dumb - transmissions are more valuable than brakes." To which I replied, "Not when I'm bearing down on an emergency with a full load - I won't care about the cost of a transmission then, but I'm gonna be glad I saved the brakes for when I really needed them - and so are you." He told me to turn around and head back to the yard, he was satisfied that I had safety in mind. 😎
Correct that softer material clogs more. Hence, when taught to use a wood rasp (essentially a file for really soft material), I was shown that back-dragging was necessary to remove what had just been caught by the teeth. But I don't think it has any effect on dulling those teeth - nor do I think that stuff like aluminum or brass or silver or gold are hard enough to damage the teeth of a hardened steel file.
Well... I am not a machine! I like to get a cut flat and even. If I were to cut one direction/ forward only I will get a flat and even cut. Using a two direction cut there will be a rocking motion and I will lose the precision of finished product I demand of my self. Yes ..I use a file card and clean the file frequently depending on the material I am working with. The slightest chip in the file and I get a scratch... which is UN-acceptable!