I'm running into an issue where at some point while printing my filament will unload completely out of the chameleon. I have manually adjusted my timings to be unloaded right at 1" before the y splitter. I have verified this by sitting and watching to confirm each color unloads to roughly the same position. And have adjusted my loading times accordingly.
But for some reason occasionally while printing bigger prints it's almost guaranteed that at least one color will unload completely from the chameleon. This hasn't been consistent with a specific color/position. It's usually completely random which one unloads too much but it's typically whatever color was previously used that it unloads too much before loading the new color. Obviously this isn't ideal as it ruins the print. I haven't been able to catch this actually happening as it usually happens after a few hours of printing. But as you can see in the timelapse where it happens. In this example Blue gets pushed out of the chameleon system but white is being fed with no issues.
It tries to change back to blue but can't because it's completely out
of the gears of the chameleon. I'm not entirely sure where else to look for this. Running small test prints this doesn't happen at all. But anything longer than about 2 hours this happens almost everytime. My button coordinates are dialed in to a T so I know it's consistent with pressing the switch. Anyone else run into this and find a solution?
Yeah I had this same problem from cross-talk like Bill said.
Sometimes it would unload T2 if T1 was loading. So T2 would not print again basically
It's possible you're getting a "cross talk" issue where when one is loaded, another is unloading. This can happen for a few reasons.
The filament drive gear is dirty and is rubbing the other color while the active one is printing. - to fix, make sure it's cleaned out.
The drive gear isn't perfectly aligned with the filament and is engaging two filaments, one forward and the other backwards at the same time, which is causing it to unload. - to fix, make sure the drive gears are perfectly centered on the filament paths. Here is a drawing of how they should be:
3. The cam is damaged, causing the system to not align properly. - examine it and if needed reprint the cam from here: https://www.printables.com/model/354998-3dchameleon-mk4-upgrade-parts-with-ptfe-grip/files
4. Tension Tuning Sliders have the bearings too close to the drive gears. - print new tension tuning sliders to adjust it. You can download them from here: https://www.tinkercad.com/things/0JBXWmRAdxn-3dchameleon-mk3-tension-tuning-sliders On #4, make sure you only replace the ones that actually are moving when not commanded, that is, the one that is unloading. And I'd only adjust it by .25 (so use the top red middle ones unless it is still happening... then go to the top left red one.)
Bill