Salvaged Robot Arm Makes A Big 3d Printer

Wow, building a precision 3d printer is amazingly easy if you can get your hands on an industrial-quality robot arm. [Dane] wrote in to tell us about this huge extruder printer made from an ’80s-era SCARA robot arm. It is capable of printing objects as large as 25″x12″x6.5″.

This 190 pound beast was acquired during a lab clean out. It was mechanically intact, but missing all of the control hardware. Building controllers was a bit of a challenge since the it’s designed with servo motors and precision feedback sensors. This is different from modern 3d printers which use stepper motors and no feedback sensors. A working controller was built up one component at a time, with a heated bed added to the mix to help prevent warping with large builds. We love the Frankenstein look of the controller hardware, which was mounted hodge-podge as each new module was brought online.

You can see some printing action in the clip after the break. A Linux box takes a design and spits out control instructions to the hardware.

34 thoughts on “Salvaged Robot Arm Makes A Big 3d Printer

  1. since the it’s designed with servo motors and precision feedback sensors. This is different from modern 3d printers which use stepper motors and no feedback sensors.

    Closed loop servos with encoders are far superior tolerance wise to steppers.

    Modern, TRUE industrial 3d printers also use encoders. It’s mainly the cheap reprap/makerbot style machines that only use steppers.

    You need to constantly know where you are and where you are going so you can correct for that in real time.

    I have been looking forward to seeing a robot arm 3d printer :)

    1. I’ll second that. It’s good to see someone who didn’t take the ‘easy’ way out. I’ve wanted to do this for years but never had the time / money / hardware to make it happen.

      If tuned properly, this type of servo gives you speed, power, AND accuracy all in one go.


  2. The world is filled with old power hungry robots that no one loves. They’re much, much cheaper than foster children and will work for you night and day.

    However, it takes some work to get them usable.
    In many cases, the servos are fine, but the control hardware is gone/dead/undocumented and no one wants to mess with it.

        1. Keep an eye on it is a figure of speech meaning watch the machine as it does it’s job. You weren’t suppose to take your eye out and put it on the arm where it will get flung across the shop and lost.

          Geez, people with glass eyes take things so literal!

          Now that I said something stupid and off the wall;
          I feel much better. I guess I needed my daily fix.

    1. ok this is cool, now I can build a 3d printer and a robot arm at the same time, and here I was wondering what to do with all these arm’s I keep making.

      kb1kanobe: how about we do this with your 10′ welder arm!? >:}

    1. Cool!

      @ elbow direction:
      I haven’t actually solved that part yet in the kinematic model, it ends up working but VIOLENTLY jerking between ‘left’ and ‘right’ forward models. i mitigated it by placing a max-acceleration in that mode, but i’m always open to a more elegant solution.

      1. I may have the source code for that still. It probably got purged during a hard drive swap somewhere along the line. It took a lot of effort to get that one code block to work and we shared it among each other after someone got it working well.

  3. That crazy B-st-rd.

    I has been wanting to say that with some of these hacks, but this one takes the cake. My dreams don’t even compare to what some people actually accomplish!

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