A high pitched noise which indicates the filament is stuck. I went in and made the chamfers a little better so the bowden tubes were in the Y-connector all the way. I have just tried this using PLA as the support material and what happened is interesting:

The first layer went down fine. The model pla printed and then the support pla first filled in a layer on the priming tower and then printed its first layer. When it came to the second layer, the model pla hardly moved during the tool change and then you could see it slowly travel down the bowden tube. It was so far away that nothing was going to print for the second layer. I think there is some kind of mechanical issue. I have a note in the SeeMeCNC site since the dual extrusion for my Max V3 is their baby. Any insight is appreciated though.

I have dual extrusion set up and mechanically it works. My problem is with PVA. For some reason, it gets blocked in the hot end and won't retract during a tool change. I was running at 200C, I upped it to 220 since that is what it took to be able to manually pull it back. It also appears to not extrude enough to be ready after a change, but this is at the 2nd or 3rd layer. I upgraded my extruders to Bondtech since I was getting way too much filament grinding and extruder clogs due to the retraction heavy prints I have been making. Any insight would be greatly appreciated.

Thanks very much! I need to modify the model with the single extruder mount to hold 2 of them. Shouldn't be too difficult.

Thanks. I will need 2 mounts, I'm hoping they won't get in each others way. I am enclosing a picture of the dual extruder setup. Please let me know if your mount will fit. If not, can you give me some specs for mounting the Bondtech? I'll be able to design a mount that way. Again, thanks -- Ivan

Sorry for the confusion. I am using the SeeMeCNC dual extrusion kit which includes a second EZR and am using the standard HE280 hot end. I turned off retraction for the PVA extruder and am only using it on the model filament. The settings I listed are for the model filament.

I just started using a dust filter (from thingiverse: https://www.thingiverse.com/thing:190118) and that may have solved my problem. Not sure why, I guess the long bowden tube combined with the Y connector and 10cm tube to the HE280 may provide enough friction under some circumstances that the filament moves too slowly through the extruder causing the extruder to grind down the filament so the extruder isn't able to move the filament anymore.

Are there better extruders that aren't so easy to jam that are compatible with my Max V3?

I have a Rostock Max V3 which I just upgraded to a dual extruder (single nozzle). I have had a weird extrusion issues that I thought went away until after I upgraded. First of all, on dual extrusions I use PVA in the second extruder and turn off retractions all together. This is because the PVA is very soft and it appears to be very easy for it to grind down and then not extrude. The T0 extruder gets clogged after a few hours when I am printing a model that needs retraction. My retraction settings are 5mm retraction, 5mm wipe and 40 mm/s speed. Someone at the SeeMeCNC forum told me that retractions above 3mm are not recommended which I think must be wrong. The Max has a long boden tube and I am amazed that 5mm works. I am wondering if this is a problem with the extruder and if there are better ones available that won't cause this problem. Of course, any easier solutions are most welcome. Advice and wisdom much appreciated.