ARCTOS is a 6-DOF robot arm based upon 3D printed mechanics running a modified version of GRBL firmware. Let’s get this straight now, the firmware is open source, but the hardware plans are a paid download, but for less than forty euros, we reckon the investment would be well worth it, judging from the quality of the build instructions and the software support already in place.
Looking at the bill of materials, there’s nothing there that is a challenge to source. The mechanical parts and casings are designed to be printed in PLA, requiring 3 kg of filament. The required layer height is 0.28mm, with a 0.4mm nozzle, so should easy to find in any decent hackerspace. The motors are the usual NEMA17 and NEMA23 steppers, paired with GT2 pullies and belts. The only required special parts are a couple of lengths of 4mm smooth stainless rod, and some M4 and M3 threaded rods, all of which many of us would have on hand anyway. The Y-axis and Z-axis both feature a cycloidal gearbox, producing decent torque in a compact format, which the team reckons is sufficient for about 500g of payload capacity. The X-axis uses a simple belt drive since all the load is vertically on the bearing. The remaining three axes (A, B, and C) are also direct belt drive. We suspect that the specified load capacity would have to include any end effector which may be fitted, so that would need to be allowed for in practice, but 500g is pretty healthy for a 3D printed unit.
On the electronics side of things, a bog standard CNC shield hosts A4988 or DRV8825 stepper driver modules and sits atop an Arduino Mega2560. No mention is made in the BoM of the rotational encoders required for closed-loop operation, but they are clearly present in the build manual. Some documentation polish is required, but there’s nothing too bad that any skilled builder couldn’t cope with. The project GitHub hosts the necessary setup files for running ROS, as well as a simple forward kinematics model for Simulink, which while very basic, is at least a start.
We do like robot walkers, robot arms, and robot worms, a lot. But sticking with just one limb for now, here’s another cracker of a robot arm project, but we suspect out of the price range of most but the dedicated of robot hackers. Don’t want heavy stepper motors, but cheap servo motor accuracy not doing it for you? Checkout this improvement.