I started using the Dual Extrusion head not so long ago and finally got around to trying some multicolor prints, but i keep getting this filament binding inside the gears and cannot figure out why.
I’ve tried the following:
What filament are you printing?
Could you purge your nozzle easily?
Maybe your z height of the first layer is too small or your filament too flexible and fast printed.
Where are your spools mounted?
The picture is Sunlu TPU, but the exact same thing happens with Elegoo PLA. Filament type/brand doesn’t appear to matter at all.
There are no clogs, i’ve checked and cleaned both nozzles.
In the print the picture happened in, it was in the middle of a print, so not a first layer issue.
Spools are in two Polymaker Dryboxes inside the enclosure behind the build plate (on the floor of the enclosure). That’s why I tried with and without the bowden tubes so check if resistance was an issue, and it’s not.
It first started happening when i was printing a print in place treasure box that has small pieces of color. So I used white for the majority and black for the small bits of color. The white never bound up like this, but the black did almost immediately. I thought maybe it was b/c it wasn’t waiting for the nozzle to get back up to temp from stand by, so i increased standby temp and no luck.
Can you Link the tpu? Just TPU (Hardness ≥ 90 Shore A) is supported.
And I cannot Imagine how Pla should be bend around. Which retraction do you use there?
Printing tpu typically needs very slow printing speed (like < 20mm/sec) and (for me) mostly 0 retraction.
Whats your toolchange retraction setting?
Printing temperatures, bed, T0, T1, speeds..
There are more possible reasons I could imagine:
I would suggest to print with prime tower and observe the print the next time when it fails.
I have the same problem with anycubic filament. It worked fine for months and now every new spool jams. I have turned off retraction, adjusted speeds, spent hours messing with it, sometimes james in minutes, other times in hours. Drying filament lets it go longer but result is same. Changes to hatchbox or creality filament or the snapmaker filament and everything prints fine. Jams for me only happen in the left head of the dual. Worked with anycubic support and got nowhere. But new spool fails, spool i have had for months of same filament different color same settings and it prints fine. Changed brands and two weeks now no fails. And testing failing filament with single extruder also fails. I think they changed formula and its too soft now.
Is this happening on both nozzles?
The hotends still include a PTFE liner, which sometimes degrades and causes such problems. You may need to replace the PTFE liner.
For me it is not that. I swapped in new hot ends and problem persisted. When it followed to the single extruder i determined it was filament and not machine related.
While the picture is showing TPU, i use PLA the most and like I said, this happens with PLA to. It’s a matter of printing with both hotends and not the filament.
I took my hotends entirely apart and found that they actually don’t have the PTFE liner at all. Not sure why as these were the ones that came with the dual extruder.
I cleaned them as best i could to make sure there were no clogs, including soaking everything in Methyl Acetate over night (couldn’t get any ethyl acetate, everything was closed and my wife had some nail polish remover that had this instead of acetone). Cleaning everything did not help.
I tried moving my spools to reduce distance and friction, didn’t seem to help at all.
If i just print a single color, from either nozzle, everything is fine, no issues.
I print at 220 for my PLA filament, but have all the other settings the same. I thought maybe it was the idle temp going down to 150 and then not back up fast enough. So I tried setting idle temp to 220 also. No luck, but the binding wasn’t as bad. I’m going to reduce the retraction distance from 16mm to like 3mm or something also to make sure nothing soft is getting backed into the gears.
Other than the 220 printing temp, i’m using defaults in Luban for everything.
