Setting the Linear Advance K factor to improve print quality

Jerome Herbert brought to my attention that there is something called Pressure Advance/Linear Advance tuning. In looking it up I found it is the M900 command and is supported by the last version of Robo Marlin. I just started using the tuning tool from Marlin: https://marlinfw.org/tools/lin_advance/k-factor.html and could see that for me a K factor of about 25 was good. ( I am now seeing if it translates to better prints)

On the LCD in options -> eeprom -> advance settings you can see adjustments for K and R0. Does anyone know how to adjust R0. For now I am using the settings -> GCODE scripts -> and adding "M900 K25"

I am posting the last version of Marlin Code Robo had, which includes the M900 linear. I am also posting the version of Marlin I use to compile without bugs . I am also including a Hex editor. I search out the Robo name for my machine and the do a search and replace with a new name using the same number of characters. This allows me to have a reference for my changes. As long as the number of characters are the same it is okay to edit the hex code.

Just take the hex code and put it on a USB drive, goto files on the LCD USB and run the hex code.

https://drive.google.com/file/d/1-9G3DqEJBj6Ij6g693GBRFivEWTn7be-/view?usp=sharing, https://drive.google.com/file/d/1VJbKnYBNBaj2MGi5N9iI_ZXe1eGTvC6w/view?usp=sharing, https://drive.google.com/file/d/1o6Y_jwGPM3XeRI1E-sb3Y2swW8ra8D9U/view?usp=sharing

 

I didn't start tinkering with Linear Advance / Pressure Advance until after I switched to Klipper, so I have no idea what good values for Marlin might be. That said I've found that this tool https://ellis3dp.com/Pressure_Linear_Advance_Tool/ does a a really great job helping to dial in the value.

One thing to note, the value will vary between filament types, nozzle temps, different nozzles, etc. Hell, I have even seen different colors on the same brand and type of filament have significantly different values. So I've found it best to tune this value for each filament I use and store it in the slicer profile for each.

 

I am confused I see where I can put K into the eeprom or use M900.

I do not see where I use PA

 

Pressure Advance is the klipper term for linear advance. They do effectively the same thing.

I can hardcode a specific PA value into the klipper config, or I can pass a SET_PRESSURE_ADVANCE macro in as part of my gcode. This is pretty much the same thing as M900.

 

I do not use Klipper and would believe that it is a rare usage among Robo owners. I think that the test pattern and the result I posted at the top is what most users need because it can be directly entered into the GCODEs in Octoprint.

I sure am glad that you pointed out K factor, I use now on all of my prints.

I keep on learning