Calibrating a Vyper with Klipper

FDM 3D Printers
#1

Good evening everyone!

So, I installed Klipper on my Anycubic Vyper a while ago after reading some post about how it being the cure for baldness and rather than keep having to re-compile my own Marlin version just because I want to tweak a setting.

I seem to have some problems with getting a good PA result, attaching images below. Bulging corners causes for example other prints with need for precision to not work at all.

IMG_20220712_220027
IMG_20220712_220059

Using Cura.

Settings:
Filament: eSUN PLA+ Grey
Temp: E 205 B 60
Speeds: Outer perimeters 50mm/s, infill and inner perimeters at 100mm/s, Initial layer 25mm/s
Retraction: 2.5mm at 30mm/s
Cooling: 70% with dual 5015 blower fans

Klipper is configured with a PA value of 0.489 from the formula of (0 + 24.45 * 0.020) as given by the documentation.

Got the measurement from a print of the PA model from Klipper github.

IMG_20220712_222038
IMG_20220712_222111

Am I doing something wrong here? Anyone else with a vyper running klipper that care to share some knowledge on getting this right?

#2

Try testing with a larger model, ex: 200% calibration cube. It will give you more accurate results.
But don’t forget to calibrate flow rate first, before doing the PA calibration.

#3

Hi and thanks for the suggestion. :slight_smile:

I did the following things.

  1. Disabled PA by removing the set values in my printer config
  2. Measured sections of the filament, used your calculator and was surprised to see an actual value of ~1.71 (I thought eSUN was good… :smiley: )
  3. Ran flow calibration with a hollow cube, came up with that 102% of flow in Cura should be set
  4. Performed the process of PA calibration, now measured 21.64mm giving 0 + 21.64 * 0.020 = 0.4328 to set as PA

Then I printed three calibration cubes, with variation on PA and scale.

cubes

Leftmost: No PA set
Center: PA set to 0.4328
Right: PA set to 0.4328 but cube is 200% scaled

Closeup of the last one.
largecube

Still seem to be bad rounded corners and edges? Both on the X and to the right…

Do I have to do anything else than set the pressure_advance value in the extruder section of the printer config?

#4

I would also recommend you to check the PTFE couplers during printing. If you notice a small movement, then you need to cut a small piece of tube an insert it again to eliminate that.
You can also increase the PA value a tiny bit more. For ex. 0.45-0.46 and see what you get.
Also note that Sunlu Grey seems to have a higher PA value compared to other brands, so you will probably need to tune that again if you plan to change filaments

#5

I marked the bowden tubes and observed and I could not see that they moved in/out from the couplers. Especially the extruder since the one from Bondtech grips quite well it seems.

Tried printing a new 40x40 cube and changing PA value myself in intervals.

IMG_20220714_115644

Can’t really see much change?

Even tried to print a regular 20x20mm with .7 PA, still bulging corners.

What’s odd is that the PA calibration cube thingy show actual PA change while these not so much?

#6

I use the PA test on this page GitHub - AndrewEllis93/Print-Tuning-Guide

I get better results with the PA here, than with the tower method. Follow the steps on the page.

#7

Thanks for the tip! Checking it out right now. :slight_smile:

#8

It’s a great guide in general. It’s my tuning go-to.