This Week:
This week I was finally able to fully assemble and test the stage (images and video at the bottom of this post). My meticulous modeling and dimesioning resulted in every single part being perfect and the entire assembly working right away. The only modifications I had to make was the holes I left for screws being a bit too small because of the printer’s kerf and thermal shrinking. But that was quickly resolved with a drill and a few bits. It was honestly immensely satisfying to see the whole assembly working perfectly after spending so many hours in solidworks and assembling it all.
As for the belt, that was a bit more problematic. For some reason, there is far more resistance to movement than I was expecting. After some debugging, I couldn’t find any indication of why this may be. My leading theory is that while each roller might have low resistance, all 8 together plus the magnetic resistance of the steppers results in a much larger total force. Regardless, the entire assembly is very sturdy, enough to resist the motors attempting to drive past the limits of the stage. The steppers also have far more than enough torque to easily overcome the friction on the belt.
Schedule:
If I can get the motor code fully working by next week, we will be well on schedule to completing our MVP the week after carneval. Now that I’ve seen how strong my parts are, I also don’t think there is much risk of mechanical failure. I also made sure to buy and print at least one spare of every single component that’s not metal so we should be totally fine even if something breaks.
Next Week:
As I aluded to in the last paragraph in the first section, I’ve also started writing code for the steppers. My plan for next week, once the limit switches arrive, is to finish the code on the uno. That will include: basic coordinate translation, homing, and calibration. I also plan to do a stress test once that is all in place to see if fans are actually necessary. While writing the code, I was running the steppers at a respectable 400RPM and neither the steppers nor the drivers got especially warm.
Time allowing, I also plan to try and interface the two arduino: the mega controlling the sensors and the uno controlling the motors. Should that work as it should, we may even have movement to detected devices done by interim demo.
Media:
Manual movement of the belts to simulate the motors moving. Next week I’ll have videos of the stage moving via the motors.
https://drive.google.com/file/d/1Pu_YjtrhgJjbOOEIajq9W80HExhFK8x3