Minor layer shifting issues

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Forsaken
Posts: 2
Joined: 19 Jun 2016, 10:14

Minor layer shifting issues

Post by Forsaken »

Hello everyone!

Within the last week I tried to switch over to KISSlicer instead of using Cura/Slic3r/Craftware and I'm actually pretty happy with it. The overall Print quality is a lot better, yet I have one unsolved quality issue which I can't get rid of.
I experience minimal layer shfting issues with KISSlicer, which don't occur for any other slicer. I'm quite sure this is some kind of hardware problem, since I only experience it on the (most heavy) y axis of my MendelMax 1.x style printer.
Minimal layer shifting on the y axis
Minimal layer shifting on the y axis
I experimented a lot on limiting the different axis speed/accerlation and jerk settings using the marlin firmare of my printer (while yet keeping the same gcode from kisslicer) but did not manage to resolve this issue at all. For the most recent test I went down to the very conservative values of:
- 20mm/s for maximum Y feedrate
- 300mm/s² for maximum Y accerlation
- 5mm/s for XY jerk
Question: Those firmware limitations should enforce the given maximum speed/accerlation/jerk settings for the y axis, no matter what maximum speeds I used for slicing right?
My idea: I want to set the limits of my firmware to match the limitations of my hardware (as precise as possible) in order to prevent any errors like this regardless of the slicer settings.

The layer shifting does not seem to stack up. It acually seems to always cancel out upon the full print. Also those shifts always occur on the exact same layers of the print.
Beside adjusting the limits of my marlin firmware I mentioned before, I checked the following things on the hardware side:
- Tension of my Y axis belt (tried to give it more or less tension)
- Current of my Y axis stepper (also tried more or less current)

You can download the gcode I am using for testing using the following link:
https://drive.google.com/open?id=0B_Rx7 ... 3hiNk1Fdms
It uses this modified marvin model from thingiverse:
http://www.thingiverse.com/thing:716077

I would be happy about any ideas and constructive feedback.
Best regards from germany,
Jens aka Forsaken
Dreide
Posts: 66
Joined: 07 Nov 2014, 15:23

Re: Minor layer shifting issues

Post by Dreide »

Could it be backlash?
Also make sure to limit acceleration for both, printing and travel paths (M201 and M202, respectively).
Forsaken
Posts: 2
Joined: 19 Jun 2016, 10:14

Re: Minor layer shifting issues

Post by Forsaken »

Dreide wrote:Could it be backlash?
Also make sure to limit acceleration for both, printing and travel paths (M201 and M202, respectively).
Thanks for your idea!
Backlash could actually be the answer to this behavior, if the other slicers (try) prevent this by e.g. going always in the same direction before starting the permimiters. I will do some more research about that.
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