Filament loading--a possible software enhancement?
This post is for the Prusa team, or other members of the community that can hack the firmware. I don't have those skills.
As everyone who uses an MMU3 is aware, unless the tip of the filament is perfectly straight and has a nice, trimmed point, it can be difficult to thread the filament over the pulley and into the PTFE tubing at the front of the unit. Often, I find myself unscrewing the idler assembly and manually directing the filament into the PTFE tube.
I've examined the failure mode in some detail, although admittedly unscientifically. In my experience, the filament tends to miss the tubing by riding over it, rather than deflecting side-to-side. Last print, I tried something. I manually rotated the idler so that the bearing was positioned almost engaged over the pulley, but just a couple of mm forward of the fully engaged position. This created a guide and I was able to easily slide a non-perfect filament into the PTFE tube.
I'm wondering if it would be possible to create an additional screen, similar to loading filament, perhaps termed threading filament, and that allowed the user to cause the idler to rotate to the correct position so that the filament is guided into the tubing. Not sure I'm expressing myself well, but I hope you folks get the idea.
RE: Filament loading--a possible software enhancement?
The upper part with the idler (drum with bearings) must not be too tight. The idler bearings bend the filament away from the Teflon tubes Even the recommended position of the screws to adjust the idler pressure is too tight. For me, the setting where I place the idler on the toothed rollers and lightly tighten the screws just enough to catch them in the nuts. And everything has been working as it should since then.