Had a motor issue with our main auger motor, previously a geared DC motor. It turns out that torque ratings for DC gear motors are for peak load only, and not continuous...and that the continuous load is only about 1/10th of the peak (so much for a 3:1 factor of safety...)
After much experimentation, we've switched over to a stepper motor for the main auger. This involved changing both the control scheme and physical implementation of the MixFlow melting section so that the stepper's constant speed could be reliably translated into a constant pressure to the plastic. Performance has improved in a number of areas including reliability, tolerance for non-uniform input material, power efficiency at higher speeds, etc. However, intelligent extrusion is not as reliable at this point as there is no pressure feedback...work is being done on the algorithms to try and restore this functionality, but for now testing and design for manufacturing are moving ahead to speed delivery to our Ingiegogo backers.