PETG coming out uneven, lumpy, and messy
I am using an almost new spool of filament that I opened a few days ago. I printed a 1 day print (not huge, but 50% infill) and it all came out okay. Then, a few days later, I tried to do another print that's had several issues. I've addressed some on another thread, but this seems to be a totally different issue. I'm printing with PETG and the filament is coming out lumpy and uneven. It looks like there are sections of the 2nd layer that don't have any filament there. When I tried reloading the PETG into the nozzle, the filament that came out during the purge was lumpy and often would just gather in a bundle or tangle around the tip of the nozzle.
Here's some of what I'm getting. This was taken during a print. The 1st layer looked just fine, but I saw this in several places on the 2nd layer. The 3rd was even worse.
When printing the third layer, it was such a mess, I stopped and just peeled it off the print bed.
This is bent from peeling it off the textured sheet. You can see where a 4th layer started printing over this, using gyroid infill. Also, on the left, near the top, you can see a big lump of filament that came off the print head.
I'm using an MMU3, so I unloaded the filament, ejected it from the MMU, cut off some of the end to remove damage, then ran it through again. When I loaded it into the printhead and the printer purged the first part of the filament, what came out was not constant - it was lumpy:
On this photo, it's easier to see the lump by looking at the shadow first.
I unloaded the PETG and ejected it from my MMU and put in PLA instead. It behaved better, but not perfectly. I tried loading it multiple times and sometimes I still got a tangled clump on the end of the print nozzle when it purged the filament.
I live in a high humidity area. Inside the thermostat reads (this time of year) between 55% and 60% humidity. I'm wondering if the issue with the PLA is due to humidity. (The PLA was new, but when I opened it up, I saw the plastic bag was torn, so it had been exposed to the humidity for weeks.) I've had humidity issues at times (until I got a filament drier), but I've never seen PLA develo problems unless it was out for a few weeks. Could PETG develop humidity issues in a few days?
If it's not humidity, what else do I need to check to fix this?
Could PETG develop humidity issues in a few days?
PETG can develop humidity issues in a few hours...
That's typical wet filament behaviour, if you listen carefully you may hear the popping of steam bubbles as it forces extrusion out of the nozzle and messes up the internal pressures.
Cheerio,
RE: PETG coming out uneven, lumpy, and messy
Could PETG develop humidity issues in a few days?
PETG can develop humidity issues in a few hours...
That's typical wet filament behaviour, if you listen carefully you may hear the popping of steam bubbles as it forces extrusion out of the nozzle and messes up the internal pressures.
Cheerio,
Thanks! I was thinking of all the other things I'd have to check, like cleaning my print head (did a bit of that, but it's such a pain to take it apart) and anything else that might be going wrong. I guess I'm lucky, then, that it took a few days before I had issues. I put the filament in a drier last night and I'll run it through another cycle today and try again.
I don't have room for a cabinet in my workshop, so I'm planning on building an in-wall cabinet for filament storage.. (The wall has a crawlspace next to it, with enough room, as long as I put insulation around the cabinet walls.) I'm really looking forward to having a humity-controlled cabinet for storage instead of the plastic bags, since so many don't hold the vaccuum well.