Automatic Cut-Off Saw Takes The Tedium Out Of A Twenty-Minute Job

For [Turbo Conquering Mega Eagle], the question was simple: Do I spend 20 minutes slaving away in front of a bandsaw to cut a bunch of short brass rods into even shorter pieces of brass rod? Or do I spend days designing and building an automatic cutoff saw to do the same job? The answer is obvious.

It’s only at the end of the video below that [TCME] reveals the need for these brass bits: they’re for riveting together the handles of knives he makes and sells. That makes the effort that went into his “Auto Mega Cut-O-Matic” a little easier to swallow, although we still think he ran afoul of this relevant XKCD. The saw is built out of scraps and odd bits using angle iron as a base and an electric die grinder to spin a cut-off wheel. A small gear motor feeds the brass rod down a guide tube until it hits a microswitch stop, which starts the cut cycle. Another motor swivels the saw to make the cut then moves it out of the way so the stock can advance. The impressive thing is that the only control mechanism is a series of microswitches, cams, levers, and springs  – no Arduino needed. Heck, there’s not even a 555, which we find a refreshing change.

Yes, it’s overkill, but he had fun and made something pretty ingenious. [Turbo Conquering Mega Eagle] always has something interesting going on in the shop, and we couldn’t help but notice him using his aluminum-melting tea kettle to make some parts for this build.

26 thoughts on “Automatic Cut-Off Saw Takes The Tedium Out Of A Twenty-Minute Job

  1. Many moons ago, I had a homework assignment which consisted of 50 or so quadratic equations to solve. The thought of the mind-numbing tedium drove me to write a program to solve them. I spent way longer writing the program than I would have just doing the work (little-to-no experience coding at the time), but the task was interesting instead of boring.

    Today one could just google a solver, or make a quick solver in Excel/Sheets/Calc.

      1. I found HS math a horrible tedious waste of time, I woudl “get it” the first time, and the 50 more times I had to do “it” in homework were torture. So I never did my math homework, I took a zero on every homework assignment. I never studied for math exams either. And I got 100% on every test in about 10% of the time the test was supposed to take. All it did was really piss off my teachers.

        I went on to get a Math degree. And I learned just how poorly taught and pointless HS math really is. It really is a complete waste of time. My HS calculus teacher said she couldn’t believe I got into a university math program. But at university, I very quickly learned she doesn’t know a thing about math.

        1. I fully understand. I did really well in math all the way up until high school. During high school math I found myself utterly lost a significant portion of the time. I didn’t struggle with the material, I could never seem to figure out the classes though. I was told that I was mediocre at math, despite testing really high on standardized tests. Foolishly, I believed that I was in fact mediocre at math and I let it convince me not to pursue an engineering degree. Almost 20 years later, after a military career, I went back to school for that degree. It turns out, I’m not mediocre at math…I’m kind of amazing at it.

          What most high school teachers know about math couldn’t fill a thimble. What they know about inspiring students to pursue careers in mathematics and math intensive fields is even smaller than that. Math should be taught by people that actually use it, not by people who took a dumber down version of it in order to get a teaching certificate.

        2. “This is the only student who has answered me poorly, he knows absolutely nothing. I was told that this student has an extraordinary capacity for mathematics. This astonishes me greatly, for, after his examination, I believed him to have but little intelligence”

          Examiner – commenting on Evariste Galois

          And let’s not forget the possibly apocryphal tale of Niels Bohr and the barometer

          “A physics student at the University of Copenhagen was once faced with the following challenge:
          “Describe how to determine the height of a skyscraper using a barometer.”

          The student replied: “Tie a long piece of string to the barometer, lower it from the roof of the skyscraper to the ground. The length of the string plus the length of the barometer will equal the height of the building.”

          This answer so incensed the examiner that the student was failed immediately. However, the student appealed on the grounds that the answer was indisputably correct, and the university appointed an independent arbiter to decide. The arbiter judged that the answer was indeed correct, but that it did not display any noticeable knowledge of physics. To resolve the problem, it was decided to call the student and allow six minutes for him to provide an oral answer. For five minutes the student sat in silence, his forehead creased in thought. When the arbiter pointed out that time was running out, the student replied that he had several extremely relevant answers but could not decide which to use. “Firstly, you could take a barometer up to the roof of the skyscraper, drop it over the edge and measure the time it takes to reach the ground, but too bad for the barometer. “If the sun is shining you could measure the height of the barometer, then set it on end and measure the length of its shadow. Then you measure the length of the skyscraper’s shadow, and thereafter it is a simple matter of proportional arithmetic. “If you wanted to be highly scientific, you could tie a short piece of string to the barometer and swing it as a pendulum, first at ground level, then on the roof of the skyscraper. The height of the building can be calculated from the difference in the pendulum’s period.

          “If the skyscraper has an outside emergency staircase, it would be easy to walk up it and mark off the height in barometer lengths. “If you wanted to be boring and orthodox, of course, you could use the barometer to measure the air pressure on the roof of the skyscraper and on the ground, and convert the difference into a height of air.

          “But since we are continually being urged to seek new ways of doing things, probably the best way would be to knock on the janitor’s door and say: “If you would like a nice new barometer, I will give you this one if you tell me the height of this building.”

          1. Ugh. To succeed in school (not life, just school) you need to learn how to play the game. The game is not to solve the homework or test questions, the game is to demonstrate you learned the teacher’s way of answering the question. When you actually have to solve a problem that isn’t a test or homework you can choose to do it any way you like and the way the teacher wanted you to do on the homework or test is one of many tools you can use. In the above barometer problem the goal wasn’t to figure out how tall the building was, it was likely to show that you learned how to use the difference in it’s reading to determine the change in altitude. Yes, a lot of teachers are dumb, I can count on one hand (5 or less, not 31 or less) the teachers that have inspired me over the years. I just wish I would have learned to play their game a lot sooner. School wouldn’t have been as confusing to me. I was not a very good student and have a full spectrum of grades to prove it.

          2. I can remember my grade 2(?) teacher marking my papers wrong every time we did division because I had a neighbour teach me short division and after I learned that, I absolutely REFUSED to do the long division method that my teacher insisted I use. She also insisted that the brightest students in the class (of which I was one) could only do more interesting things after we had done all of the easy, boring stuff that the rest of the class was doing. (I also remember her literally throwing my workbook at me one day because I spent most of my time daydreaming and not doing my work.)

            If any of y’all want to have your eyes opened even further that the stories told in this thread, check out David Cayley’s The Education Debates.

        3. Read the foreword to Sylvanus P Thompson’s book on calculus. He says much the same.
          (Likewise I never did the homework, slept through math at school, and scored a A. Teacher told me I didn’t deserve it.)

        4. Yes pointless to the person who never had trouble learning it instantly.Who doesnt need help understanding it.Who didnt need a tutor.Teaches are the way they are cause all people arent like this.They would teach differently if everyone was like this.Also were you that good in all your other classes?Maybe,but then maybe not ,other classes you actually did the homework and had to listen to the teach teach their way.other people thats every class,and everything.for some people they passed it.

  2. I once worked in a paintbrush factory. The factory floor was amazing – it was full of one-of-a-kind machines, designed and built by hand, that performed all of the steps for making paintbrushes, from cutting and finishing the tips of bristles (both natural and synthetic, to gathering these into precise bundles, to clamping them to the handle with a ferrule. This factory had evolved over time, starting from making paintbrushes completely by hand. Various processes were mechanized, one at a time, until the only manual operations left were putting the brushes on their retail hanger cards into boxes, and stacking them on pallets. There were even radically different machines for doing the same job (such as bristle tip finishing) for different types of brush.

    In another life, I watched a turn-of-the-(20th)century sock knitting machine at work. The machine must have taken years to make the prototype for, but once finished, I’m sure the improvement it made in production speed made it possible for all of us to have socks.

    And let’s look at the electric light bulb. People think that Edison’s greatest invention was the incandescent lamp. But no. First of all, he wasn’t the first to invent an incandescent lamp. What he WAS first at was inventing a machine to MAKE incandescent lamps, and this was true genius.

    That is where this sort of process leads.

    1. He oversaw a research lab where paid thinkers solved the problems of creating a machine to use a vacuum pump to make a light bulb and took credit for the creation because he had created the tool that created the solution to the problem. Neither the bulb, the pump, or the idea of floating glass on molten metal to heat form it were new. He did not *invent* it at all; complex systems are generally not comprehensible in their entirety to any single individual *at one instant in time* unless the overall process is divided up into understandable subsystems. What Thomas Edison really invented was the modern idea of the research lab that aggregated credit to its owner, board, or founding entity. he also (calously?) killed an elephant in one of the earliest, sickest snuff films of all time when he used the spectacle of a frying elephant to try to “prove” that AC power– that essentially everybody uses today unless.they live in an RV or on a ship– was unsafe by killing an aged female Indian (Asian) elephant in 1903 at Coney Island, New York. In his defense, he was a man of his day and a died in the wool urban denizen. He probably never saw or interacted with an animal in a positive capacity either before or after this sad incident. It’s not much of a defense, but he wasn’t out harpooning Sperm Whales or chopping the last Stellar Sea Cow to death with a boarding axe for a dollar a week minus berth and board. The turn of the last century was a brutal time in many ways. We live in an age of wonders where we don’t have to worry about much and we can post rambling opinions of long dead industrial legends from the comfort of the couch. LLaP

    2. You mean, the engineers that Edison hired invented the first machine to make incandescent bulbs? Actually, I find no reference about the early Edison bulbs being made in an automated production line.

      Edison’s main contribution – or rather his team’s – was to further develop the carbon filament and figure out a way to “metallize” the carbon by turning the filament partially into graphite. This had the effect of lowering its resistivity by a factor of 100 and the filament could be made thinner for the same operating voltage. A thinner filament was more efficient, so the bulbs were brighter.

  3. “The impressive thing is that the only control mechanism is a series of microswitches, cams, levers, and springs – no Arduino needed. Heck, there’s not even a 555, which we find a refreshing change.”

    This is the way it should be done. The simpler the better. This will no doubt still be cutting after the caps in any electronics dry out an die. There is just less to go wrong. Things tend to get complicated enough on their own. Also, when designing things for other people, having a very simple system they can see and understand is very nice for them. 5 years down the road if you have steppers hanging off a micro and one of them stops stepping the customer is SOL. With a simple design he can look and say, gee that microswtch is acting up. Nice job.

    1. If you like this approach as much as I do, look up the Browne & Sharp screw machine.

      Screw machines are a kind of extinct (but still usable) class of lathe that operated like this (albeit only mechanical means, cams, springs, levers, and gears) to make some very complex repetitive parts semi unattended.

      Perhaps I’m biased because I’m a machinist and I don’t always go to electronics to solve my problems though I do occasionally, when it comes to mechanical process I like to see mechanical solution because of the reason you stated- there are screw machines over 80 years old still happily working, precisely because no electronics. And yes, some even run off steam power.

      1. I am a bit of a machinist and a bit of an electrical hacker. Way too long and strange a pedigree to list, but I do thing there are a lot of places that are better off without electronics. Electronics have their place, but as one who both collects old radios and wind up record players, I can tell you plugging in a “newer” old radio will almost guarantee smoke, while there is a very good chance a wind up record player will still function, A bit of oil may help but again, it does not take a rocket scientist to figure out you need to oil the sticking part. You need to know a lot more to dig into an old radio.

  4. The late Douglas Adams addressed this in his book “Last Chance To See”…

    “I have a well-deserved reputation for being something of a gadget freak, and am rarely happier than when spending an entire day programming my computer to perform automatically a task that it would otherwise take me a good ten seconds to do by hand. Ten seconds, I tell myself, is ten seconds. Time isvaluable and ten seconds’ worth of it is well worth the investment of a day’s happy activity working out away of saving it.”

  5. The servo slowly turning off the cutter power-switch that could (and should) have been activated by a trip pin and the sparks as the still-running grinder bottoms out at the end of its travel made me wince a bit. Rather than gripe about it, I’ll propose that there are further questionable time-investments to be made to increase the joy of this sort of thing: Tinkering with it until it’s ever-so-much-better-than-the-prototype.

    We’ve all been there.

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