My multi-color/-material printers

[spegelius]

I'm currently battling some jamming issues with the Tronxy. I had to reprint some of the idler levers of the extruders and suddenly the tool changes are very finicky. Part of the problem is some small clearance issues on the levers due to the clone Bondtech gears not being equal, some of them have deeper grooves where the teeth are thus requiring the idler to close more. Also since the Bondtech gears are geared, the gearing itself doesn't allow the gears to close enough for good grip if the groove is too deep. Should have bought real Bendtech gears... not sure if I should just order the real gears. Couple of the filament change failure seemed to be due to lack of grip from the extruder so definitely can't rely on these. They do work ok for normal printing, but the filament change movements do require dome extra grip and torque, especially if the filament tips aren't perfect.

Another part of the failing tool changes might be the elevated temperature in the room during summer. The filament tips are more stringy, which eventually clogs the feeder part. I hope I can get that sorted out with tweaking the tool change gcode. Swapping filament to hotend isn't simply pulling one out and feeding another, the filament tends to stretch and have those wispy strings. Also the tip swells a bit when cooling so it might be simply too big to fit to the throat. And all this is quite random, a print could go well for an hour and then there's one single failed tool change which either fails the print by jamming in the feeder or leaves a gap due to missed layer.

Here's a couple tips that could be better, but usually feed ok. Also a picture of print that has parts missing due to failed tool changes. MMU2S apparently has a feature to detect failed filament changes which is a good feature. OTOH if the failures happen at this rate, it basically means babysitting the machine quite long, for example this print with 6 colors would probably taken 2 days or so, multicolor printing is slow.
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