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I am trying to set up the linear advance on my Mega S. My current set up includes TMC 2209s with no modifications (just pulled the old drivers switched the plugs and installed the new ones.). A Hermes / Hermera extruder ( Bowden) and a v6 hotend. Currently using Marlin 22.214.171.124.
Printing PLA / PLA+ at 206C
Print speed 45mm/s
retractions were set to 3mm
loading speed set to 28mm/s
unloading speed 90mm/s
although I am able to get a smooth surface on most of the print I have artifacts as follows. The dark blue benchy shows print quality without linear advance enabled.
Does the 2209s fix the issue with linear advance on the extruder that the 2208s had?
I would say the dark blue benchy looks better as print quality compared to the other print...
Did you properly determined the linear advance K factor? For a Bowden configuration it is very low. And it is obviously incorrect, a wrong K kills the details and edges - like in the light blue print.
You have and a (too high) temperature problem there, the stringing for PLA is easy avoidable.
BTW, it is such a pity to keep a Hemera in a Bowden configuration...
The only change between the two prints aside from the colour of the filament is the addition of linear advance. I have tried larger K vales but the results are as follows. Thus I lowered the K value until the other artifacts disappeared. Should I have gone the other way and increased it?
If you want to use linear advance you have to determine it; read carefully, generate testing patterns, reduce the range, generate new testing pattern etc
Just for reference: K depends on configuration and filament. On my Bowden machine with Capricorn PTFE tube, E3D V6 and dual gear extruder (BMG clone), the determined K was 0,77 for PLA.
Tested and re-tested 5 times with the same results. After many trials and errors, I determined that the issues were the length of my retractions, the filament that I was using and the heat-break and nozzle. Replaced the old heat-break and nozzle. PID tuned the hot end again and ran the test once again. things looked better however, I still had the echoing ahead of the X on the calibration cube. At that point, I started to decrease the length of my retractions. That eliminated the echoing. Now all that is left is to dial in the temperatures to perfect the print.
Thanks for the hints. I finally settled on a K value of 0.78 and a retraction length of 2.4mm. Still not happy with the bridging over the doorway so some temperature adjustments are in order however it is an improvement over the previous benches. Please excuse the colour of this Benchy, it was a good way to get rid of the mountains of sample PLA I have acquired .