major failure
MMU2 all installed, first print was just a single color piece, all good.
second print, some parts for a spool holder on the wall. all going ok to start when i returned at the finish. the filament had formed all over the hotend, over the wiring and up the back, melting the thermister cable and even though the extruder was in the finish position. the temps was still on 215 and when i pulled some of the stuck filament a big pool dripped all over the place, very dangerous. its ruined the hotend and cabling. i feel that since i added the mmu, the system is no longer as reliable. any thoughts?
RE: major failure
Looks like you had a failure of the part coming loose from the print bed. This can happen just as easily without an MMU when the bed is dirty or contaminated.
You should consider a silicone sock for your hotend as part of your repair. It will make things like this less likely to be as catastrophic, since it helps prevent the molten plastic from sticking to the heater block in the first place - it just blobs and droops rather then basically sucking itself around the entire thing and sticking.
RE: major failure
Yeah unfortunately the blob of death is not something unique to MMU setups.
I had some PETG try it on me (with the MMU disconnected), but I was lucky to catch it before it was more than just a mess to clean up.
Sorry it happened right as you were getting somewhere with the MMU. Trying to get my first 2 color print done it decided to jam so bad I had to tear the hotend down to it's individual parts to clean it out. Not as bad as your mess, but I totally feel for the frustration.
RE: major failure
a failure like this has nothing to do with the MMU, the part you printed lifted off the bed and caused the blob of death to form.
could happen on any printer in any configuration.