Strange print issue, need new eyes to help troubleshoot

Basic Information:

Printer Model: Ender-3 S1 Pro
MCU / Printerboard: STM32F401RCT6 (Stock)

Fill out above information and in all cases attach your klippy.log file. Pasting your printer.cfg is not needed

Describe your issue:

I just finished installing and tuning klipper and my prints are having the issue pictures below. Overhangs are printing terrible. And it seems like it only affects the first 20cm or so. Didn’t have this issue with marlin. This print was with a wall speed of 90mm/sec, 3000mm2/sec accel. I’m pretty happy with the rest of the print. I’ve adjusted everything I can think of to fix this but it keeps coming out the same way. It’s just odd that it seems isolated to the lower part of the print. Is this some kind of overheating issue. I tried printing at slower speeds I was using on marlin with the same result.

Welcome to Klipper. This looks to me like a classic case of printing PLA too fast with insufficient cooling. If you watch the printing, you will probably see the edges of the layers curling up…

I’m thinking so too. It also looks like the radiant heat from the build plate may be playing into it since it is only the overhangs close to the plate. It was also about 20 degrees warmer in my garage than usual today. It is cooler now and I started a new print with the bed at 40 lowered from 60 and raised the min layer time to 10. We will see what it does. Looks like I need to upgrade my part cooling fan. This is a pic of the print I just took off.

So I ran down the overheating issue, and have decided to upgrade my part cooling, however it looks like my issue was pressure advance related. Left is with PA=0.04 and right is with it turned off. Not sure what I have done wrong. I calibrated PA per the klipper documentation. Any idea’s?

I don’t know about pressure advance being the root cause. It would only affect print areas where the extrusion significantly slows down or speeds up (seams, corners, etc.) Your previous photos clearly showed the issue on constant speed extrusions like the external perimeters. Pressure advance would also not be really affected with the wall slope angle (within reason).

If your printer is otherwise well tuned, I personally prefer to use the “Voron recommended” method of pressure advance tuning. But you have to make sure that your bed is well leveled and your mesh is working well.

AndrewEllis93 Pressure Advance Tuning

It is extremely quick, uses almost no filament and the results are much easier to select.