Anycubic Predator printing skews in Y direction

[CoolioX]

Greetings --

Recently, my Predator was having issues where it would automatically zero out at a higher position that it should have. As a result, I attempted many things (physical tightening of belts and software autocalibration) to try and get the printer to resolve. Thanks to this forum, I got the height issue resolved, but NOW I have issues where printing a simple XYZ calibration cube finishes in some messed up ways.

To demonstrate this, I printed out a series of calibration cubes around the print bed. I've labeled them in the photo 2.1 - 2.7.

First how I positioned them on the bed:

Then, in a row:

They all seem to have some skew in the Y-direction.

Additionally, here's a photo of my height map (which seems extremely irregular)

Also attached, are my config, config-override and bed files:
bed.g
config.g
config-override.g

Any advice will be graciously accepted. Thanks so much!

Thanks in advance!

[droftarts]

@CoolioX I’m sure you’re already familiar with the Duet delta calibration page, but can’t hurt to go through it again: https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer

I also found this page useful for understanding what the bed mesh was trying to tell me: http://boim.com/DeltaUtil/CalDoc/Calibration.html

Ian

[CoolioX]

@droftarts -- Thanks -- I have gone through "Calibrating a Delta Printer" many times previously. I should point out that at some point, my Predator WAS working with the Duet board, so I'm still trying to work out if it's a mechanical or software issue. I'll check the second link. Much appreciated!

[jay_s_uk]

@CoolioX

I'm guessing its more than likely mechanical.
I run a duet board in my predator without issue. In fact, looking at your config, you're running my version anyway.

I've recently had to change a few mini wheels on one of the axis due to poor quality bearings. I have also had a belt snap. I would suggest removing a tower/axis at a time and stripping it to parts and inspecting.

[CoolioX]

@jay_s_uk -- and thank YOU for your repo! It was a great help to getting me started!

[CoolioX]

Thanks to everyone for their help and suggestions! Turns out it WAS totally a mechanical issue. There was a grub screw that fell out of the stepper motor pulley on the back motor. Here are the results after adjusting!

Original in Purple, new in BLUE:

[jay_s_uk]

Glad you got it sorted