As the saying goes — when life gives you lemons, you make lemonade. When life gives you a two-ton surplus industrial robot arm, if you’re [Brian Brocken], you apparently make a massive 3D printer.

The arm in question is an ABB IRB6400, a serious machine that can sling 100 to 200 kilograms depending on configuration. Compared to that, the beefiest 3D printhead is effectively weightless, and the Creality Sprite unit he’s using isn’t all that beefy. Getting the new hardware attached uses (ironically) a 3D printed mount, which is an easy enough hack. The hard work, as you might imagine, is in software.

As it turns out, there’s no profile in Klipper for this bad boy. It’s 26-year-old controller doesn’t even speak G-code, requiring [Brian] to feed the arm controller the “ABB RAPID” dialect it expects line-by-line, while simultaneously feeding G-code to the RAMPS board controlling the extruder. If you happen to have the same arm, he’s selling the software that does this. Getting that synchronized reliably was the biggest challenge [Brian] faced. Unfortunately that means things are slowed down compared to what the arm would otherwise be able to do, with a lot of stop-and-start on complex models, which compromises print quality. Check the build page above for more pictures, or the video embedded below.

[Brian] hopes to fix that by making better use of the ABB arm’s controller, since it does have enough memory for a small buffer, if not a full print. Still, even if it’s rough right now, it does print, which is not something the engineers at ABB probably ever planned for back before Y2K. [Brian]’s last use of the arm, carving a DeLorean out of styrofoam, might be closer to the original design brief.

Usually we see people using 3D printers to build robot arms, so this is a nice inversion, though not the first.