Being unsatisfied with our test pieces up to this point the day started out with us in the process of reconfiguring our extruder. We were encountering problems with what we believe was a back pressure issue. Our paranoia about getting the HDPE to stick to the build surface caused us to mash down on the first layer which would lead to pressure building up in the tip with nowhere to go except backwards. I've lost count of how many times we've had to change that thing but it's near a dozen by now. The good news is I think we got it this time. Making changes to the auger and barrel seems to have made our extrusion reliable which has always been the goal (elusive as that goal has been).
|Our new motor mount|
|Using Brandon as a size reference|
We quickly modeled a small canoe, set up Big Red, plugged in three ventilation fans, ran a dry run, and prepped the surface. This was it: the moment of truth. Could we press go and let Big Red take over? The answer was no. Of course not. During our print of the base raft the extruder's drill motor began surging so Adam had to sit there with his finger on the trigger the entire time to deliver the appropriate amount of plastic while the computer operator tried to adjust the print speed on the fly. The sudden change in behavior of the drill motor was baffling. It was Adam though that suggested we reconfigure our extension cords so that the motor was not sharing an outlet with the ventilation fans. That did just the trick.
Our test when we finished
The fruit of our endeavors is a small-scale canoe which shows us that we can go large scale. What we will likely do during the big print is print the raft alone then feed the printer a separate set of G-code for the layers.
|The pretty side|
|The less pretty side|
I won't count my proverbial eggs before they hatch, but I think we got this. Let's show Seattle what UW students can accomplish in 2 months worth of free time and some recycled milk jugs.
|Brandon thinking about his idea for "concrete skates". Just a little too small.|