One of the biggest uncertainties going into this project concerned torque. Inkjet printer motors only need to drive a lightweight plastic header and maybe an ink cartridge. Depending on its purpose, the motor of a 3d printer would have to drive a 1kg filament spool of plastic, a bed with a printed object on top, or even an entire axis assembly. It did not help that I was borrowing skeletons from inkjet printers – because an inkjet printer is only intended for horizontal motion, I decided the best way to go was a static x axis driving a mobile z axis mounted on top of it. Doing otherwise with a mobile x axis, such as seen in a standard reprap, would put more weight on the z axis than could be born by a gear/pulley system. This was also very similar to the wolfstrap setup I’d been working with for the base.
Before continuing any further, tests would have to be done. Here, I test the motor driving the x-axis. A 1.5 pound exercise weight I had lying around simulates the approximate weight of the z axis I was working with. The endstop was also tested, which was scavenged from a printer and tacked on to be interrupted by some random ridge on the printer’s structure. An arduino was simply programmed to drive the motor until it reached the endstop, then backup.
The x-axis would turn out to be the only axis which absolutely, positively needed a stronger motor. This is without surprise the only axis which would drive the weight of another axis. The y-axis was perfectly able to drive its weight however the particular motor I’d found used a smaller step size and appeared jittery. Opening another printer could have potentially fixed that issue. The extruder I’d purchased came with its own motor and I figured I would save some effort just sticking with that.