Stepper-Controlled Chop Saw Automates A Tedious Job

We’re not going to question why [Absorber Of Light] needs to cut a bazillion little fragments of aluminum stock. We assume his reasoning is sound, so all we’re interested in is the automated chop saw he built to make the job less tedious, and potentially less finger-choppy.

There are probably many ways to go about this job, but  [Absorber] leaves few clues as to why he chose this particular setup. Whatever the reason, the build looks like fun, with a long, stepper-driven threaded rod pushing a follower down a track to a standard chop saw. The aluminum stock rides in the track and gets pushed out a set amount before being lopped off cleanly as the running saw is lowered by a linear actuator. The cycle then repeats until the stock is gone.

An Arduino controls the stock-advance stepper in the usual way, but the control method for the linear actuator is somewhat unconventional. A second stepper motor has two cams offset by 180° on the shaft. The cams actuate four microswitches which are set up in an H-bridge configuration. The stepper swivels back and forth to run the linear actuator first in one direction then the other, with a neutral position in between. It’s an interesting approach using mechanical rather than the typical optical isolation. Check it out in action in the video below.

We’ll admit to some curiosity as to the use of the coupons this rig produces, so maybe we’ll get lucky with some details from [Absorber Of Light] in the comment section. After all, we knew exactly what the brass tubes being cut by the similar “Auto Mega Cut-O-Matic”  were being used for.


23 thoughts on “Stepper-Controlled Chop Saw Automates A Tedious Job

  1. I’ve built Arduinos into projects before, but when I get everything working, I’ll solder wires directly to the pads on the controllers and any external sensor or driver boards. Building a breadboard into your project is… kinda Rube Goldberg level of over-complication.

    But good job on the automation. Love being able to whip up a solution to a repetitive task.

  2. If I had to make thousands of those little fidgets I would look for a cutter with a smaller kerf. Perhaps a plasma cutter. More up front cost, but a job that big should pay for it, and you would waste less material.

    1. Plasma cutters are sloppy and inconsistent in aluminum. Arc wants to wander all over the place, the slag gets everywhere and you have to clean it, and the tips get burnt up quick.

      Bandsaw would be ideal, but slower. Aluminum is cheap enough and I imagine his margin is wide enough (if he didn’t have a good margin, he wouldn’t be willing to make thousands of them) that using a chop saw isn’t hurting him.

    2. There are benchtop-scale bandsaws for small stock cutting that would be much better suited than this was, but you use what you have I suppose.

      Wouldn’t a relay or two substitute for that stepper-driven switch system? Also using the hex coupler as a lead screw might be a good idea if you blew the chips out every minute or so, otherwise, maybe not so much. It’ll be interesting to see what happens as it gets used.×2000/494/49466_2000x2000.jpg

    1. Look closer, the stock is supported across the whole length between two strips of aluminium. It’s the lead screw that’s supported in two places, which doesn’t matter much.

  3. I both like this project and dislike it at the same time. I like the thought he put behind it and all that it does but he could have accomplished the exact same thing and IMHO much more elegant if he would have just designed a cam to do those processes. Not everything needs to be over complicated with code and electronics

  4. OMG, just stack them up. Bundle together 20 or 30 and cut them manually. That saw making noise all day long would drive me crazy. Since it’s thin, a custom shear cutter is also worth considering.

  5. with aluminium that thin, this seems to be the most inefficient way of doing this possible. The cost of running the saw alone starts being a factor (lots of wear on those bearings for relatively little working time). Stacking 10 of these strips in parallel would be a start. Alternatively, if you really need multiple 1000s of these (I can’t find why though? What use is having 1000s of 1″ squares of aluminium?) a custom jig and a pneumatic shear would make short work of it.

    1. Just found in the Youtube description: “They will eventually become brackets to fasten computer monitors to metal enclosures”

      Seems like the perfect job for a metal stamping shop. With the right die you’d have one of these with a single press stroke, ready to go, with holes and all. And a run of a few thousand would probably take a day. Also sounds like a product that should just be picked from existing parts catalogue. If anything a metal stamping shop probably has a generic shearing die, and could do a run of a few thousand of these for cents a piece.

      I understand the will/hope/dream to do everything yourself with the tools you have, but sometimes if all you have is a hammer, it’s better to pay someone that has a 10 ton excenter drive repeating press.

    2. It’s a decade old $50 Craftsman from a yard sale special…..

      Bearings? Run time? When the saw wears out you toss it in the dumpster and grab another off of craigslist.

      You can’t just stack the material to the moon and chew through it like the cookie monster. Blade deflection, vibration shifting the material, heat degrading the carbide on the blade, etc…. What a great way to make everything you do sloppy and inefficient.

      So many comments on here from people who don’t work with actual tools. He went through the effort of getting the accuracy of the setup within .002 inches of tolerance, and your best recommendation is that he should change that to .2 because “efficiency”.

      1. Stacking 2 to 5 should be NO problem for this saw at all. Stacking 10 probably neither. Choose the right blade and it should be fine.

        If you can get no better than 0.2 inch accuracy on a saw like this you should really stop using a tool and and junk it because you can do better with a hand saw and a ruler. I couldn’t make my saw do that if I tried!

        I work with actual tools. In fact, I get paid for it. Which is why I’m questioning why you’d choose the methods chosen by [Absorber Of Light] for what is presumably a paying job. My boss would be questioning why I didn’t just outsource it if I built a contraption like this. My time is probably more valuable than the savings. I have worked in a metal stamping and forming company in the past. Spitting out brackets in aluminium was measured in tens of thousands of units a day.

        He made it work with the tools he had, more power to him. I’m just saying that there are other, and probably more efficient methods out there. Don’t be blinkered to ONLY the tools you have. There’s more out there.

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