1 missing layer during print.. and after all ok again
Since a couple of days I run my trusty Prusa i3MK2 with the MMU upgrade. Everything works ok and as expected. One small glitch on my second test printout with a missing layer at about 15mm height. It was Extruder 2. See this image:
Also the purge block has the same missing layer in it. I suspect that either the filament got stuck momentarily in the 'multiplexer'' unit at the point when it enters the extruder. I think it is at the PFTE entry. When trying to push through the filament manually during the assembly, I could feel some minor resistance of that specific hole. Measuring the length of the filament when getting stuck clearly pointed to said interface at the PTFE tube with the tapered entry. The other 3 entries where 100% smooth. Since I couldn't solve the problem I thought - ok let's try it anyway.
The first print was all fine:
So I thought - ok no worries with the slight force the the entry. But the Nikko dog model at the entry of my post made me think again whether I should check this again.
Any thoughts what to check - or how to modify the PTFE tube (I've measured it's length - it was correct 40.5mm and even 0.5mm shorter than Prusa's drawing). I could see that there was a small gap at the lower end of the small multiplexer block - that was caused by a too long PTFE tube. But mine is even shorter than the drawing.
Thanks for any suggestion!
John