Over the past two weeks my work has been centered on the mechanical structure of the computer stand and testing of the stepper motor. I designed and built a structure on top of the platform jack that allows the linear actuators to change the pitch of the computer. This involved machining, and screw hole placement.
I also performed testing on the stepper motor, testing the motor at a variety of different input voltages and speeds to determine if it has sufficient torque to lift the computer (it did not).
Before this motor testing, I also researched a constant current (chopper) driver for the motor because we realized that we were using the incorrect type of motor driver. After finding a suitable driver with the right input voltage range and pin connections to our arduino, testing was possible.
Since the motor still did not have enough torque after testing, I researched gearboxes that would make the NEMA 17 have enough torque. We found a gearbox with a 5:1 ratio and a torque of 3 Nm. I calculated that we require a torque of 4.4 Nm to lift the computer but this is the worst case when the stand is in a state that is rarely exercised (all the way down).
One of the new skills I learned was to calculate the torque required to rotate a power screw (a type of screw in a platform jack). This involved straightforward physics and allowed me to better judge what kind of motor gearbox we needed. I learned this skill from a video. I also learned how to measure the main characteristics of a threaded rod so I could easily replace it with another from McMaster. I used the McMaster guidance to learnt this.