Topics created by selkovjr

Thanks to everyone for useful suggestions. I have tested all and got wildly different results. Then I dug in a bit deeper into this whole calibration issue and found that there is really no good way to do it without dismantling the hotend. The best option is to calibrate the thermistor in a precise bath thermostat before putting it in. You might be able to obtain a sensible result by doing an in-place calibration if your hotend is small and well-insulated, but with the Diamond Hotend, that is nearly impossible.

I went ahead and did it the hard way, using a trick that does not seem to be easily reproducible. I did realize early on that it was a stupid thing to do, but it was too much fun to quit, and in the end, I did achieve a passable result. I have summarized my findings at https://github.com/selkovjr/gt-2-thermistor-experiment

The next time I have to do it (my bed thermistor is next), I will construct an external thermostat.

David, your suggestion that it could be104GT seems to have been spot-on, although the best-fitting curve looks almost parallel to 102GT, which is an odd one in the family. It is possible that it is a somewhat odd 104GT. Maybe it is a QC reject. Its room-temperature resistance is within the norm but the estimated B value is almost 3% off. I posted a couple NLS fits on that github page.

Yes, I had noticed pressure advance and it did help a little bit, to the extent that I was able to find an optimumal setting. But it did not solve the problem.

Here's what happened. I guesstimated speed and acceleration limits from major resonance modes, and they turned out to be pretty good estimates, but I forgot that the g-code commands for setting those values expected per-minute velocities. The result was mesmerizing. I just sat there and admired the smoothness of motion. I took it as a sign of Duet's intelligence and forgot to check whether the character of the movements I observed had anything to do with the values I had entered. Best of all, I thought, was that none of the motion was transferring to the walls of my apartment. Surprisingly, that newfound smoothness didn't really affect the overall print time too much, so I didn't realize what I got wrong until much later.

Today I found and corrected the error, and now the machine shakes like crazy again, but it produces passable prints. Not bad for a second try. The strokes are still thinner in the middle than near the ends and there is a small ridge on the top surface where the infill meets the perimeter. Traces of ringing are visible on the sides but are not really palpable (way under 0.01mm) – which is an excellent result for a frame that is not famous for its rigidity and a print head whose total weight is approaching 1 kg.

Thank you for thinking with me. I wouldn't be making as much progress without your help.