My first print with Bambu Lab PETG-CF had bed adhesion issues, which a thin layer of paper glue fixed, thanks to amazing people here who helped me.
My second print with this filament was much bigger disaster, though.
The 3D-printed mouse model had thick filament ‘hairs’, protruding from the surface.
Have a look at the attached pictures.
Would anyone give me some insight into why is that hairing happening?
Some surfaces are beautiful whereas some ruined the model completely. There are even holes in the printed support.
Printed by A1 mini with 0.4mm Hardened Steel hotend, using the default profile the creator has provided.
Since you have a drier, weight the spool before (in grams) and after drying to see how much moisture was removed. Keep drying until the weight stabilizes.
If the dryer has a relative humidity measurement in the drying chamber, it’s important to note the reading before removing a spool to weigh.
Weight absolutely is great for knowing how much weight was lost but the RH measurement gives a solid clue why if the weight doesn’t change much or at all.
Yes it does seem odd but my thoughts about that is the moisture in the filament is causing it to “spurt” filament as it prints that takes a little time to build up on the nozzle, which eventually is transferred to the model in clumps.
I was also a bit worried if the increased filament friction could be the cause because the spool sits on rotating tubes. Even though there are bearings in there, the spool is a bit harder to rotate by hand than it was on the printer’s holder. However, I am unsure what exactly an under-extrusion looks like.
Mostly true, I did not notice that.
However, when looking at this photo and then on the slicer, this part was not printed with any gap and yet it’s got defects
Did you happen to notice the humidity in the filament dryer when you pulled the spool? Even better - did you weigh it before and after drying to know how much water was lost? Added - Actually not better but of similar importance.
Unfortunately, I do not have a precise scale to measure the water loss. However, the humidity meter was saying 32% before drying, and 22% after drying.
22% is actually pretty good but I think you said you’re using PETG-CF. That may need to be more dry than other filaments based on all the advisories to dry PETG.
I’m just starting to use PETG-HF and dried to 21% IIRC and my prints are coming out well but what I’m printing with it now isn’t that demanding.
Not sure. I’m out of ideas. I’m sure someone will have more though.
I don’t see any noticeable difference between the three prints… I don’t know how I can help you, because I use the default settings and everything works fine.
But I think is not a humidity problem…
I think I found the culprit. Seems like this filament is extra sensitive to an accurate flow rate. After making sure the spool moved smoothly and re-running the flow calibration, the print came out amazingly well.
Today, I discovered that the flow rate wasn’t good enough because the nozzle was clogged.
When I switched to PETG Translucent filament, the first layer had quite a few small blobs of translucent filament.
Suddenly, a few millimetres of dark PETG-CF filament were extruded. Thanks to the switch to translucent filament, the released clog was clearly visible. After stopping the print and another flow calibration, the print turned out to be perfect.
This was my first experience with a nozzle clog. The under-extrusions in all my PETG-CF prints were clearly caused by these clogs, and the flow calibration only compensated for the blockage.
Hopefully, my inconvenience will help someone else.
