Notifications
Clear all

New k value?  

  RSS
Nino Nobile
(@nino-nobile)
Member
New k value?

Hello guys!
I was reading that there is a new k value, is that already in force in firmware version 3.8 firmware?

http://marlinfw.org/docs/features/lin_advance.html  

 

 

Posted : 23/09/2019 1:23 pm
bobstro
(@bobstro)
Illustrious Member
RE: New k value?

I believe the new version is scheduled to be included in 3.9 in November.

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 23/09/2019 1:45 pm
Bunny Science
(@bunny-science)
Noble Member
RE: New k value?

Like Bob said, it is not in Prusa's 3.8.0.

You can get LA 1.5 in custom firmware like mine (just comment out the 0.9 degree X & Y motor defines

https://github.com/guykuo/Prusa-Firmware/tree/0.9-Degree-Stepper-Support

or  

https://github.com/prusa3d/Prusa-Firmware/tree/MK3_LA15

 

Posted : 24/09/2019 4:28 am
Nino Nobile
(@nino-nobile)
Member
Topic starter answered:
RE: New k value?

@guy-k2

Thank you very much for that data, how are you doing with the new LA? Do you notice improvements?

Posted : 24/09/2019 1:19 pm
Chocki
(@chocki)
Prominent Member
RE: New k value?

I'm using Guy's firmware with a Skelestruder and find that the K adjustment is at  0.1 for PETG and PLA, why it can go up to 2.0 is plain daft, it retracts mm's once I set it above 1.0 from the looks of the extruder gear. To be honest 0.1 is too much and it could do with being 0.05

I wonder if there is a scaling bug with the 3.5 gear ratio or something as it seems wrong. In my case all adjustment would be between 0.01 and 0.2 not 0.1 and 2.0.

This post was modified 5 years ago 2 times by Chocki

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.

Posted : 24/09/2019 4:40 pm
Bunny Science
(@bunny-science)
Noble Member
RE: New k value?

decimal values are OK. Just set up the range and step values to test from 0 to 0.5 when you are making the Marlin test code.

With LA 1.5 values end up 0.075 to 0.1   

MUCH lower than with pre- LA 1.5. K is completely redefined in LA15.

If you have not tested with the Marlin code generator, I would leave it off or at 0.1.

This post was modified 5 years ago by Bunny Science
Posted : 24/09/2019 5:01 pm
Chocki
(@chocki)
Prominent Member
RE: New k value?

Thanks Guy,

It was this part from the Marlin documentation that had me thinking the minimum value is 0.1 and must go up in increments of 0.1

Thats great news, going to re run K calibration.

New K value required

As the unit of K has changed, you have to redo the K calibration procedure. See next chapter for details. While old v1 K values for PLA might be between 30-130, you can now expect K to be around 0.1-2.0.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.

Posted : 24/09/2019 6:50 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: New k value?

marlin has to support bowden fed printers , which will have much higher values the direct drive extruders

 

Posted : 24/09/2019 7:01 pm
Chocki
(@chocki)
Prominent Member
RE: New k value?

Wow, I've never used a bowden fed extruder, I had no idea they need squish the filament that amount from what I've seen moving on mine, and the printing speed must have to be so much slower to allow for that amount of filament retraction and de-retraction to print accurately etc.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.

Posted : 24/09/2019 7:52 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: New k value?

bowden printers have to deal with the flexing of the filament in the bowden tube acting like a spring between the extruder and the hot end and so use larger retraction settings to unload the spring and then retract the filament from the hot end.

one problem with people looking for advice on prusa printers and reading advice for creality printers is the difference between bowden and direct drive

Posted : 24/09/2019 8:35 pm
Share: