So my MendelMax 3 took a nose dive on me about a month ago. I had purchased and added the Auto Bed Leveling kit to the system. The steel plate that's used for the sensor that replaces the aluminum plate had a bit of a bend in it by the time it was said and done and as a result I ended up with a head crash on the plate as it was reading too far down.
Pretty much my fault for not noticing and thinking it through. Anyway I couldn't get the plate as flat against the glass as I wanted so I flashed the firmware back to the original so I could print something for a friend.
And that's where things went south. Every print was ending up like corrugated piping on the outside kind of like ^^^^^^. The layers repeated on all four sides so it wasn't bed slippage. Every 5 or 6 layers there would be a 'fat' layer protruding out making a ridge.
Long story short nothing we tried, I engaged the MTW folks on several occasions and in the end we were all stumped. Since I travel through the town they're in about once a month they were kind enough to accept my ask of could I bring the printer with me next time I passed through.
But then work took a nose dive and things got hectic and I just didn't have free time or in truth the enthusiasm to look at the printer for awhile.
Then this last weekend I needed to escape the world so I cleared some space and took the printer apart down to its component parts. The only thing I left intact was the wiring on the Rambo. IT takes less time to strip a MM3 than it does to build it but not a lot less since you have to take care to keep everything grouped etc.
I looked for any irregularities during the deconstruct, loose screws, things not butted against each other, shifting, out of alignment blah blah blah. Nothing.
Okay well I can't take a pile of parts to MTW so I build my printer for the second time from piles of parts.
I run a calibration cube and WTF, literally I said WTF, as it printed mostly good. As part of my troubleshooting I'd re-installed MC and S3D on different PC and thus didn't have anything but the default settings, none of my tweaks were there. So there was some zits on the sides here and there. This is also a third (fourth) brand of filament that I was trying, again as part of the troubleshooting just to rule out the ridiculous thought that maybe the three other brands of filament I had that had printed great before had all 'gone bad' at the same time.
So I tweak some settings from memory such as retraction, coasting, heating, cooling and print it again. And this one was as good as my first print.
Again I go WTF...
So I print an Elder Wand (bad design by the way, it's printed laying down so it requires supports and the shallow curves at the top and bottom result in layer artifacting. But asided from that it printed perfectly.
So yay, I have a great printer again. Why it messed up, I have no idea. How it got fixed I have no concrete idea. I mean obviously tearing it down and back up again fixed 'something' but what that was may remain a mystery.