Help diagnosing print quality problems

[martincho]

I could use a little guidance on how to fine tune S3D to produce better results. Factory file attached.

Basics

• PETG

• 0.8 mm nozzle, hardened steel

• 230 C nozzle, E3D volcano, BMG extruder

• 60 C bed

• 100 mm/s nominal speed

• Ball-screw/stepper driven machine, custom built

This is what I think is going on

• A - Might be a cooling problem?

• B - I think this is caused by the infill rather than any mechanical issue

• C - Z seam showing through

• D - Not sure...z seam issue?

• E and F - At first I thought this was due to some kind of a backlash issue with the Y axis screw/nut. That doesn't match what I am seeing on other prints and the lower portion of this print. Now I think it might be related to the infill and how it changes shape at those locations.

Again, I'd appreciate opinion on how to address the above.

[greybeard]

I posted this viewtopic.php?f=8&t=7353&p=50780&hilit=petg#p50780 awhile ago - scroll down toward the bottom of post to find my input...

Review my posted file and test part. Will probable need to adjust Flow Multiplier to correspond to your nozzle size. Then, bump up the speed as needed.
And, 'sinking' like seen in your photo is, as you suspect, most often due to infil. Thus, increase infill %.
Note: PETG does require cooling to avoid sinking and stringing...

[martincho]

Well, after trying different ideas Pressure Advance fixed the problem. I still have some tuning to do but the improvement is beyond obvious. It fixed more than the basic problems I was having. I'll fine-tune some more but this is the first setting I've touched that's actually made a real difference when it comes to blobs, zits and z-shift defects.

Here's the requisite picture. This is not a Bowden setup, so a low Pressure Advance setting of 0.05 was all I needed. I had it set to 1.0 and it was too much: