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Struggling with Revo Six and MMU  

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Henry
(@henry-2)
Estimable Member
Struggling with Revo Six and MMU

I installed an MMU on my printer a few months back and the process went very smoothly. I had one model that I printed that gave me significant trouble, but otherwise, the MMU performed nearly flawlessly. Last weekend, I installed a Revo Six and this fan mod at the same time. Since then, I've had nothing but trouble. All of my filament has been recently dehydrated for 8-14 hours at 60 degC. These are the symptoms I'm seeing:

  1. PETG prints stick much more strongly to the bed now. My Atomic Filament Perfect Yellow leaves behind a very noticeable ghost/residue on the textured build plate. This ghost cannot be cleaned with alcohol, and it almost always pulls off the bed and onto whatever I print next. My black, red, blue, and green don't seem to exhibit this issue. I think this means that the filament is too hot. Perhaps a low live-z can cause this? I did recently raise it up 0.2mm, but haven't tried yellow on the first layer again.
  2. On an MMU print, the purge block is terrible. The bridges sag multiple millimeters and very frequently break. They then get pulled/warped so that the strands tend to point nearly straight up. This leads to nasty messes on the block, often transferring boogers to the nozzle or causing collisions and messes. Does this indicate the temperature is too high? That's where I'm leaning because of the significant sag, but then again, it is essentially liquid as it comes out of the nozzle. I never had to monitor the MMU previously, so I don't know what the inside of the wipe tower looked like on the other hot end. The layer fan was disabled, just as with my V6, except for bridging. For some reason, the wipe tower isn't treated as a bridge in PrusaSlicer.
    https://forum.prusa3d.com/wp-content/uploads/2022/04/20220331_155902.mp4
  3. The supports printed within the wipe tower (the tall, thin, vertical walls) almost break apart simply by touching them. There's almost no layer adhesion.
  4. I designed this part and can dang near crush the thing by hand. The front thin part snaps off easily without bending. Then I easily pop off the top section with the numbers from the back part of the print. Then, with a bit of effort, I can break apart the rest of the model by hand. I think this suggests the temperature is too low.
  5. The surface sheen of a large part is much duller than when I printed the same part with my V6. I think this suggests the temperature is lower than when printing with the V6.
  6. I enabled the fan at 30%, which helped the purge block tremendously. It still looked like hot garbage though. I printed another one of the models (from #4 above) and swapped out the cooling fan mid print, returning that component to stock. From that layer and up, there's a notable improvement in quality. I'm not brave enough to try and break the print by hand though, at least not yet. I want to keep it until I try and print another one.
  7. My thermal camera shows the nozzle at 170°C (sock is removed... accidentally broke it while removing it) while my setpoint is 230°C. Will PETG even extrude at 170°C? I'm not sure which temperature reading to trust.
  8. There's a significant difference in print appearance with the sock removed.

I think most of the data points to the temperature being too low. If the nozzle actually is 170°C, would it even print? I suppose as a test I could try printing with the setpoint at something higher. I would expect there to be a temperature gradient from the thermistor and the nozzle surface, but I wouldn't expect 60°C.

Postato : 03/04/2022 3:52 pm
Henry
(@henry-2)
Estimable Member
Topic starter answered:
RE: Struggling with Revo Six and MMU

Dang, I can't edit my previous post because time expired. But #8 is incorrect. I paused the print again and tightened the nozzle and the appearance looks the same again as with the sock on the nozzle.

Postato : 03/04/2022 4:02 pm
Henry
(@henry-2)
Estimable Member
Topic starter answered:
RE: Struggling with Revo Six and MMU

I think the 170°C was incorrect now. I believe it is more likely that it was caused by simply trying to read the temperature off of a metal, reflective surface. I also bumped the temperature up about 10°C and the surface is looking glossier. I'll probably go up by another 5 to 10°C.

So many knobs to turn...

Postato : 03/04/2022 11:14 pm
Henry
(@henry-2)
Estimable Member
Topic starter answered:
RE:

oh holy hell. I'm so incompetent. Terribly, terribly incompetent. My "Atomic Filament Perfect Yellow" is PLA. It isn't PETG. This totally explains why it is leaving a residue when printed to the bed, why it won't adhere to the other PETG in the wipe tower, why it does all kinds of stupid crap, and why the tips on it are so much more difficult to shape than the tips on my other PETG filaments that are PETG.

I grabbed the wrong danged spool. I've been testing and tuning for over a week now. Dozens, if not a hundred, prints to try and get this working. 

There's so many clues that make sense now. Like why it every so slightly melted the strands together in my dehydrator. Why it sags when I try to bridge with it. I'm in this weird limbo where I'm ashamed, but I'm also terribly happy too.

Postato : 03/04/2022 11:45 pm
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Henry
(@henry-2)
Estimable Member
Topic starter answered:
RE: Struggling with Revo Six and MMU

Oh... I'm slightly less happy. My wife pointed out to me that due to my stupidity, I spent $400 yesterday on an IR camera so I could verify the nozzle temperatures. I'm too stupid to read a label, and it cost me $400.

LOL. At least I can laugh.

Postato : 03/04/2022 11:52 pm
BaconFase hanno apprezzato
gnat
 gnat
(@gnat)
Noble Member
RE: Struggling with Revo Six and MMU

You can be honest here. You just needed an excuse to buy the IR camera that the wife would buy into. We won't judge 🤣 

That sucks you went through so much frustration and time though. Definitely done that a few times myself, but as far as my wife needs to know, it never cost me that much... 🤐 

MMU tips and troubleshooting
Postato : 04/04/2022 3:16 pm
ZombiPach
(@zombipach)
Eminent Member
RE: Struggling with Revo Six and MMU

Don’t beat yourself too badly. We’ve all been there. 👍

Postato : 05/04/2022 4:01 am
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