PETG blues (well, yellow)

[supercazzola]

I'm new to 3D printing and slicing, so please be patient with me.

At first, I was just using the PLA profile and adjusting temps for PETG. Of course, the quality of the print was horrible


Then, I learned a bit about the retraction settings and print speed, and thought I was making progress. I got a decent looking calibration cube.


and I went to print an STL file that had a large flat area, with a few tabs on them, and a back that rose up, slowly and on an angle. I got a mess!


i've tried reslicing, reorienting, but for whatever reason, whenever the print gets to this part, it starts to have trouble. The dimensions of that area is pretty thin, so I thought maybe it is the infill, so I increased the # of wall layers, changed infill to 100% and I still got the same type of pattern there.
What is odd is that you can see, part of the print is ok, and then it seems that the extruder just starts to go on the blink.

It takes me a few hours to get to this, so I will try to post more photos. In the meantime, I hope someone might have an idea of what to do next.

RObo3d R2, 0.2mm, Hatchbox PETG. hotend: 255, plate: 65, print speed: tried 1500 mm/min to 2000 mm/min, retraction distance: 5mm, retraction speed 2400 mm/min
thank you for taking the time to read this post.

[dkightley]

Before you post any more photos, any chance you can sort out the photos you've posted that don't show?

Rather than trying to link in from a photo site, why not use the forum's attachment feature. Its a breeze to use!! Grey bar at the bottom of the posting window...."Upload attachment"...and once uploaded, you can place inline or leave at the bottom of your post.

[supercazzola]

Before you post any more photos, any chance you can sort out the photos you've posted that don't show?

Rather than trying to link in from a photo site, why not use the forum's attachment feature. Its a breeze to use!! Grey bar at the bottom of the posting window...."Upload attachment"...and once uploaded, you can place inline or leave at the bottom of your post.

Sorry about that.
First photo:

Second photo:

Third photo (better illustrates the issue):

Again, this issue doesn’t occur on the base of the unit, but only when it starts to print a very narrow, sloped, long shape.

[arhi]

retraction distance: 5mm

that is too much for all metal hotend so you have hotend blocking due to filament bulging.
keep below 2mm (1 should be ok, then experiment with wipe and coast)

if you are not using all metal, 255 is waaaay too much for ptfe tube.

the issue is more visible on some features, especially when you slowly extrude, due to heat creeping up the hotend. make sure "throat" of the hotend is properly cooled and lower the retraction below 2mm (ideally below 1mm)

[supercazzola]

Here is another photo - looks like underextrusion , but why would the lower 4 to 5 layers print okay? I believe all of the speeds are the same, as are the support speed multipliers

[MasterFX]

Since PETG is softer than PLA or ABS you must increase the extusion multiplyer about 5-10%.
This is because of the softness of PETG, which gets pressed more in the extruder gear and therefor the effective radius of the gear is smaller, so a lower amount of filament is transported than expected.

[supercazzola]

I changed the extruder multiplier to 1.05 and had the same symptoms. Always seems to print great close to the heated bed, and then crappy as it travels higher (bed lower). Fans are off.
Any other ideas? I tried to increase the extruder multiplier to 1.10 and wound up with a lot of blobs and some burned looking spots,
thank you

[arhi]

Always seems to print great close to the heated bed, and then crappy as it travels higher (bed lower)

tell tell sign for filament stuck in the throat is "work ok at start and gets worse as the print continue"... the filament gets stuck in throat
- because of high retraction (lower retraction)
- because heat creep (better cooling of the hotend
- in case of ptfe lined hotend - ptfe tube degradation

[gearsawe]

Is your hot end all metal? or does it have a liner in the heat break?
I have an all metal hot end. Print ABS with no problems. PETG was a problem as it gets hot it softens it almost becomes sticky if trying to slide past a metal heat break. I found this is where the problem was with mine. Unfortunately with my setup I will not be able to use PETG.

The only way I was able get a couple good parts was to reduce retraction and print faster to keep the fillament for warming up in the heat break.

As a test I removed the extruder held it with pliers and turned it on. I was able to easily push the filament thru. As heat creeped in the heat break I could feel the amount of increased force required to push the filament thru. after a couple minutes it was not possible to push the material thru. The heat creep was worse with out it being mounted in the heat sink