Under-extrusion
Been struggling with the MMU2S to run without intervention. I've played with temps, cooling steps, and load/unload speeds. I can get most objects to print, although I help it along. The worst is under-extrusion. Any tips on keeping the filament flowing? The particular filaments I've had trouble with is Ultimachine's Translucent Blue and e-Sun's White.
RE: Under-extrusion
It'd be helpful if you posted pictures and a description of the specific issues you are having. Your post is too general to offer much help.
However, MMU problems generally boil down to the following:
- Friction in the filament path
- Friction in the filament path
- IR calibration
- Friction in the filament path
- See 1-4.
RE: Under-extrusion
I've replaced the bowden PTFE tube with a 2mm inner diameter to reduce friction. I've calibrated the filament length for that. I also ran IR calibration. I'm really at the end of my rope on this one. We also have a MK2S and MK3S. I'm pretty familiar with Prusa's machines. My boss is telling me if I can't get this sorted soon, we're rolling back to 2.5S.
I'll get some pictures up on the next failure.
RE: Under-extrusion
Here is the under-extrusion.
Here is a filament that printed perfect.
Any tips to get that translucent blue to print would be appreciated. As stated, I've tried a range of temps from 190-220. The black and grey was printed to show that it's possible. The translucent failure was printed with the same settings as the black/grey.
RE: Under-extrusion
Not just the bowden tube, also the buffer/MMU input tubes. I had to ditch the buffer entirely because I found that AmazonBasics filament's rough surface texture just would not play nice with it and would constantly jam or grind. I strongly suspect you have similar issues with the brand giving you grief.
The melt temp for that filament appears to be hotter than normal. You're going to want to print a little hotter than 220, very possible this is your problem. The spec range is 190-230°C.
Try 230 or even 235. It's not just a matter of being above the melt temp but far enough above it that you can keep it molten while fresh solid stuff is still coming in.
RE: Under-extrusion
I ditched that stupid buffer on day 1. Have the filament on Universal Auto-Rewind Spool Holders ( https://www.thingiverse.com/thing:3338467 )
The holders are well tuned. Very little drag. Just enough to rewind the filament. I'll look into replacing the other PTFE tubes. I know the receiving tube after the feeder gears is tight. It catches frequently. I'll try cranking the temps up to 230+. Thanks for the input. I'll report back after the attempt.
RE: Under-extrusion
*sigh* Cranked it up to 235 and absolutely no change. Sounds like I'm getting a clog. Lots of clicking happening. No other filament gives me this much trouble. I'm pegging it on the bad tolerances of this filament. Cannot recommend eSUN or Ultimachine for MMU prints. Works fine on the Makerbots and MK2S and MK3S.
RE: Under-extrusion
Update: The tolerance on this filament is horrible. It's advertised as +/- .05. Measuring it tells a different story. It went up as high as 1.83 and as low as 1.71 (still within tolerance). I'm pretty sure that is my issue. I measured some of the other Ultimachine filament and was getting the same wild fluctuations.
RE: Under-extrusion
That'd do it. I'm guessing you could still use it in non-MMU mode without issue. Maybe contact the company and give them a heads up; worst case nothing happens, best case you get some free replacement filament that's hopefully in spec.