Showing posts from June, 2018

Too much pressure

A local company built a ram extruder for us. Not very different from a syringe extruder but massive in terms of size and pressure.

Our assumption was that parts had been sized properly, so we did not question the 8.7Nm NEMA34 stepper, nor the 5mm-thick acrylic tube with a 60mm internal diameter. After all, it was not the first time they have built a similar contraption to be used with clay.

Unfortunately, though we try to be very gentle on the extrusion test, we manage to break the tube in a few minutes. Luckily for us, it cracked without sending debris around. We did not expect that at all and when we contacted the seller all sorts of questions were asked, questions we did not have an answer for, like "what was the operating pressure?". I did not have a clue as I was just trying to get the stepper rotating very slowly. Their diagnose was we did it wrong as we set the nominal current (6A) for the stepper driver.

From torque to pressure So I was determined to figure out how …