SYSTEMS V1 TESTING
Week of 03/15
Laura Maria Gonzalez + Sandy Curth
This week we assembled the first version of our system which includes the Potterbot plunger to push the clay, a hose to feed the material to the
auger based extruder, and two motor driver set-ups with a potentiometer to manually control the flows of the two stepper motors. We did not connect
the air line for our first tests.
To use our drive setup for the Potterbot we pulled the wires for the extruder from the duet board to our Arduino system. Unfortunately this setup
failed to move the plunger and push the clay so we switched back to using the Potterbot controls. Next we tested the motor's capability to push the
clay through the hose into the auger. The clay was pushed about 1' into the hose before the motor stalled.
To fix the issue we cut the hose to only 8" from 3'. We also had to alter the Potterbot's config file to increase the extruder motor's current from
2500mA to 2800 mA and slow the feed rate. Finally, the clay was able to move through the short hose! Next we needed to connect the auger extruder
to the hose.
With both the clay plunger and auger motors running, the clay started to move through. However at about a minute in the pressure on the PLA printed hose connection split in two. This could have occurred for multiple reasons. First, PLA is not the strongest material. Even at 50% infill it still failed. Moving forward we will switch to printing in PETG. Another issue is the softness of the clay. At this point the clay may have been exposed to air and lost some of its plasticity sitting in the tube. As a result, the auger had a hard time moving the clay through causing pressure to build in the hose and clay cylinder. In the next iteration we will also be switching to a higher pressure rated cylinder since visible cracks were observed in the current acrylic version.
For the test we decided to make controllers for the stepper motor using Arduinos. For the auger controllers we used a NEMA 17 stepper motor with a
motor driver, potentiometer, 100uF capacitor, and Arduino. The motor was powered with an old xbox power supply and the Arduino was powered with a
9V battery.
References:
Superb Tech, director. Control Stepper Motor with Arduino - Tutorial. YouTube, YouTube, 14 Dec. 2018,
www.youtube.com/watch?v=_jTYygbOTuI&t=141s.