Science Vs Internet Trolls: Testing Another Kind Of File System

File testing rig

No matter what you do or say on the Internet, you’re always doing it wrong. Keyboard commandos are ready to pounce and tell you how it’s “ackchyually” supposed to be done. And so it was of little surprise when [Jason] of Fireball Tools was taken to task by the armchair millwright for his supposedly deficient method of filing metal.

But [Jason] chose to fight back not with words but deeds, building a system to test alternative methods of filing. His filing style is to leave the file in contact with the stock on both the front- and back-strokes, which enraged those who claim that a file must never be dragged back over the workpiece, lest the teeth become dull. The first video below shows the build of the test rig, which leveraged his enormous Cinncinatti shaper as the prime mover, as well as a pneumatic jig to hold the workpiece and imitate both styles of filing. Part two below shows the test rig in action, and [Jason] really outdoes himself with his experimental approach. He tested three different grades of Pferd files — nothing but the best, no expense spared — and did duplicates of each run using both the Internet-approved style and his lazier style.

The result? We won’t spoil that for you, but suffice it to say that the hive mind isn’t always right. And what’s more, [Jason]’s careful myth-busting yielded a few interesting and unexpected results. His channel is full of great shop tips and interesting builds, so check him out if you want to see how metalworking is done.

Thanks to [mgsouth] for the tip.

39 thoughts on “Science Vs Internet Trolls: Testing Another Kind Of File System

  1. The method I was shown was to file in one direction toward your body. It has nothing to do with dulling the file and all to do with safety. If you only file toward yourself, then should you slip you won’t punch the work piece and potentially injuring yourself. The same approach is applied to other tools too, like using grinders, spanners etc.

  2. I thought that this was debunked many years ago. Perhaps it is a myth that won’t die. Like the idiots who tell me I have permanently destroyed my audio transformers by testing them with a multimeter.

    1. The general reason why you don’t want to drag a cutting edge backwards is that the metal is work-hardened by the cutting forces and going the other way acts like jiggling a piece of bailing wire backwards and forwards – eventually the tip of the tooth chips off. The guy did show a bunch more chipped teeth on the finest file.

      When you’re filing softer materials like soft steel, aluminum or copper, the cutting forces are too small to make a difference and the teeth wear out more by abrasion, especially with the coarse files. The way I was told, the main reason to avoid it is because you’re pushing the chips you just cut deeper into the grooves, clogging the file faster. I do find that to be the case with aluminum.

      Even if it doesn’t dull the file, it still doesn’t make good sense to drag the file backwards because it’s not cutting (much) that way, and often the file starts to squeal. You also see people starting to rock the file and round the cut because their grip changes with the reversing forces – this guy claims otherwise but YMMV.

  3. I don’t think that the characterising of people leaving these sorts of comments as trolls makes sense. About half the impetus for the comments is probably to save a person from continuing a mistake. It is mentioned in many metalworking texts and taught in some schools that one should lift a file on the backstroke if one cares about the longevity of the tool, if you do this your whole career you just know it as advice that might help get more life out of your files. Now it’s good sense to test doctrine, and when it comes to the workshop results matter most. However his results even show that these commenters are partly but not totally correct in their understanding. If you have a delicate file you shouldn’t be dragging it back and forth with force unless you have reason or money to burn.

    1. i mean there are trolls out there who really dont care, they just want to have a contrary opinion and then use that opinion as an explanation of why they are smarter/better/whatever than the person they are commenting. this is a pretty common thing on the internet.

      but id would say that most people are just people who learned differently and think that their way was right not knowing that the subject of their knowledge was in dispute. both may have complete confidence in their craft to the point where it doesn’t even matter who was right, both can make it work their way. the thing that matters is that you put in the work and come to an understanding of what works for you. you can test it of course, but if the results are contrary to your beliefs and you have to adjust to doing it the other way, that is going to effect your craft at least in the short term.

      i push, this is how i learned to use a file, i have had good luck with pushing and my work is to my satisfaction. that’s really all that matters.

    2. I agree. Regardless of what’s going on in this situation, correcting someone who is doing something clearly wrong (especially when dangerous), and it is not just a matter of opinion, is not trolling. However, a writer who makes inaccurate claims when they know it’s untrue COULD be considered a troll. Thanks for the “article”. (coughs in youtube synopsis)

  4. Pushing a round file is ok, pulling it is pure madness. I don’t need science to know that, just try, it feels wrong. I mean very wrong. But it’s not the same for a flat file; a flat file works both ways… why? I don’t know. Also, the angle with which the file rubs against the metal is an art that can’t be done using an automatic machine. It must be done by hand. The angle varies during the process. One has to begin with an angle close to parallel in order to break through the tougher surface of the metal that seems to form due to some kind of oxidation I guess. Once this crust is gone, the softer metal can be more easily filed.

  5. mgsouth is far smarter than me. I can understand what he did, but I could not have thunk it up. The testing brings up three questions for me.

    1.) Hacksaws. Like files, I was always taught to lift on the return (also taught to mount the blade to cut on the pull stroke to avoid damaging the frame). This file test suggests that dragging the saw on the return should have no effect, but things don’t always work the we expect. Can some hacksaw blades be tested? I see no point testing Sawzall (r) blades, as lift on return is not practical.

    2.) What effect would a light spray of cutting lube have on the file life?

    3.) Woodworking. I was taught to lift a plane on return – back drag dulls the blade. A plane is heavy, and lifting on the return leads to fast exhaustion and sloppy work. I know mgsouth is running a machine shop, but is there any chance to use that rig to test a plane? Perhaps test with both pine/spruce and maple.

    1. Re: Hacksaws.
      I’m not sure about that advice, seems very impractical to lift and reset the hacksaw after every cut. Also check out older power/reciprocating hacksaws (the smaller ones that use the same blades as hand held, but on a powered crank), they constantly have pressure back and forth, and at no point do they lift the blade while cutting.

      Certain don’t push down on the return stroke, although if you’re applying a lot of down for cut the stoke you might be using it wrong….

      1. I have an old Craftsman power hacksaw that takes regular hacksaw blades. While it doesn’t lift completely off the part on the backstroke, it does have a lift mechanism to remove almost all of the pressure so there’s just enough for the blade to barely stay in contact with the part. So this may be true for some old power hacksaws, but it’s not universal.

        1. Good to know. I am mildly jealous, I’ve always wanted one of those old power hacksaws, but even a non-working/needs-lots-work one was more expensive than a horizontal bandsaw for a similar foot print (workshop space is very limited), also I kind of need less projects and more working tools…

          While looking at videos and lamenting about not getting a power hacksaw, I came across this video:

          At around 2:35 in they show parts the mechanism that lifts the blade on the return stroke.


        2. I have a Decoupeerzaag (I think Americans call it a reciproting saw or scroll saw?) and it has a setting on how much to “lift” (actually, reverse) the saw on the backstroke. Setting it to 0 is cleaner strokes, 3 is faster cuts, bus some especially soft and moist woods are impossible to cut along the grain with it set on 0, and increasing the pressure only makes it worse. So I think increasing the setting mainly makes “chip” (sawdust) removal easier, at the cost of being more agressive to the wood.

          1. I think Jig Saw is another common American term for that type of tool. Checking my Jig Saw and it has an “orbital action” setting, which I think is doing the same. Thanks for enlightenment about that.

  6. oh ffs. i read that article just for you to tell me to watch the video to get the end? some of us still prefer to get our information through reading. what’s the point of hack a day if you are just going to tell me to watch a video. stop encouraging the illiterate.

    1. We’ve known for decades that richer media is better for learning, so it’s quite the opposite of illiteracy.
      If you prefer the 20th century libraries still exist, and you could write a Fortran script to scrape the captions from videos, send them to your dot matrix printer and read them under an incandescent bulb.

      1. In this case it’s a stupid argument. This is hardly a learning material and more of a paid promotion for welding accessories. Behaviour like that was regulated long time ago in EU for radio, print or TV. Internet is sill a Wild West in that regard.

      2. We’ve also known for ages that finding information is much easier in written form.

        It takes forever to scrub through a video and find the spot where someone describes a particular fact. Scrub through, stop and listen every now and then to see where you are, scrub again. You can’t search any faster than the person in the video speaks.

        Finding a particular fact in a written (or typed) document is much quicker – text search or scan through by eye.

        Give me a textbook over a lecture (or video) any time.

        1. I think it depends on what you’re learning, I’d much rather learn plastering or welding from a video than a textbook, even though I agree in this particular case I’d have preferred text form.

          Ultimately text is quieter and I can consume it in more places so having that option is preferable to me. I can always watch the video later of I’m really interested!

      3. Different people have different learning styles. Some people learn visually, and videos are perfect for them. Some people can learn by hearing instructions. And some, like me, cannot absorb audio or video instructions and much prefer written material. And having to sit through however many minutes of video when I could have read it in half the time is torture.

    2. What, miss a great build video and all the shaper action?

      Fine, here’s a shell command that will decrypt a spoiler in ROT13:

      $ tr ‘A-Za-z’ ‘N-ZA-Mn-za-m’ <<< "Abg bayl qvq qenttvat svyrf onpxjneqf abg uheg gurz, gurl npghnyyl phg n yvggyr ovg snfgre."

      1. $ tr ‘A-Za-z’ ‘N-ZA-Mn-za-m’ <<< "Abg bayl qvq qenttvat svyrf onpxjneqf abg uheg gurz, gurl npghnyyl phg n yvggyr ovg snfgre."
        Not only did dragging files backwards not hurt them, they actually cut a little bit faster.

        Saved you a shell

    1. If you followed Fireball tools regularly, you would see that while he sells certain tools he also teaches you how to make tons of stuff like your own welding tables and belt sanders. To say he is just shilling his tools is pretty unfair.

  7. I was taught, light pressure, file away from you.
    It’s kind of like those dumb yahoo articles that say “if your’re doing
    (fill in the blank) you’re doing it wrong.
    So, my question to all these people/articles etc. is, “What business is
    it of yours?” You want to learn how to do some thing with a file,
    there is youtube, and “This Old House”/”Ask This Old House”.

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