weak patches

I've been having strange problem. My prints work great, at first. The take a little bit for the plastic to get flowing, but the raft takes care of it(although I'd prefer if kisslicer supported skirts) good bed adhesion, good flow of plastic. Then the print porgresses, and everything falls apart. For some reason, there are patches in the print, weak spots. These patches usually last for maybe a foot of linear print. Watching while the printer does this, the flow rate seems to drop to less that half of normal during these patches. It's fine again afterwards, but that's a layer that just won't hold together. This has happened in every print I have tried with this machine. Multiple brands and colours of filament, different temperature settings. Any ideas?

neptix

It could be your hobbed bolt slipping. Try increasing the tension on the idler.

Not hot enough to keep up with the flow rate. Try increasing the temp by 10c

E steps not calibrated correctly. See the tutorials page for E calibration for Kisslicer.

Extruder motor overheating and the little gear then slips. Check if the motor gets hot or if the set screws are loose.

Extruder stepper driver over heating and going into protection for a second and then you end up with less plastic then required.

Retraction speed set to high and it causes skipped steps on the extruder during un-retract which results in not enough plastic being extruded. Try reducing the max E speed by 2mm/s.

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Ok, I can rule out the hobbed bolt, the skipping is occuring at the extruder stepper, not the bolt. I redid the Estep calibration and found that it was out a bit(was 450 now 436) and that seems to have made the problem worse. I've changed the temperature from 190 to 225, and I've found it sticks best at 220. It's not a retraction issue, as it starts happening while it's still printing the raft now. The extruder motor is not overheating. I'm going to try a mechanical rebuild of the feed mechanism to make sure nothing is loose or jamming or anything, then recalibrate the drive current for the extruder. I'll let you know how that turns out.

neptix