Preview versus reality

Can anyone tell me why this:

Printed this:

What does the prime tower look like?

Could you show us the sliced results in the preview mode? The screenshot of the model doesn’t really say anything.

Wow…the prime tower has the gap! I don’t think I want to print this 4-hour print again until I know what’s going on. The first one I printed didn’t do this.

I would say the red has had a feed problem of some kind, and I suspect it would be different next time. Print a calibration cube or something simple using the red.

Actually the red started printing where it was supposed to. The gold stopped early.

Okay, tried to print a gold cube and it prints air. So I get to learn about clearing clogs in the U1.

Do I do a cold pull like I do with Bambu?

This is on the forum:

I also recommend having some appropriate-diameter acupuncture needles to hand, as barrel cleaners.

Whoa! I’ve never seen one this bad. Obviously the culprit but why didn’t the machine sense the tension? I didn’t hear any grinding.

How did you not spot that??!

It is supposed to be able to tell there isn’t any filament coming through, but according to several discussions on the forum that’s not very reliable.

Yeah how did I not spot that indeed. That’s a crazy knot.
My theory: the gear grinded just enough to tear the filament in half, but the end was still tripping the filament sensor so it kept thinking it was printing.

Remember, filament runout is detected in the printhead. If there is filament present, it will not trigger. Whether or not the filament is moving makes no difference. Tangle/air print is detected by the feeders and must be turned on via the applicable menu on the printer. It is not enabled by default.