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Z-Banding Anycubic Kossel Linear

Posted by rigs 
Z-Banding Anycubic Kossel Linear
March 30, 2018 03:42PM
Hi !

I have a "Z-Banding-wobble-zebra" problem with my linear kossel delta but I can't find the solution...

I tried:

speed : 30 / 20 / 10 mm/s --> no change
Temperature : 250 / 240 / 230° ( Petg ) --> no change
Acceleration : 3000 / 2000 / 1000 mm/s --> no change
Fan : 100 / 50 / 0% --> no change
Flow : 100 / 90 / 80 % --> no change
I tightened the belts --> no change

My settings:

I changed the print nozzle 0.4 --> 0.8 mm
Layer Height 0.3 mm

Can you help me, I'm lost !

Thank
Attachments:
open | download - Anycubic Delta Plus.jpg (495.7 KB)
Re: Z-Banding Anycubic Kossel Linear
March 31, 2018 02:57AM
This looks like a mechanical problem. IDK the Anycubic Kossel linear, so I can only guess it has some play/backlash in the rod ends or carriers.
Re: Z-Banding Anycubic Kossel Linear
March 31, 2018 07:56AM
There are lots of possible causes of banding on deltas. Here are some of them.

1. Using bang-bang control of the bed instead of PID control (common in Cartesian printers too). In that case the banding would be along the Z axis, although there might be banding from other causes superimposed on it.

2. Drivers that don't do low-current microstepping well. This is most common when using DRV8825 drivers, but A4988 drivers can be affected too depending on the motors and the supply voltage. There is a long thread about the on the forum. If the layer height is an exact number of full steps then on a simple shape like a cube, the banding will be vertical. Increasing the motor current may help, provided this doesn't make the drivers or the motors overheat. Changing the layer height may make the problem less visible. Putting back-to-back diodes in series with the motors will help.

3. Segmentation banding, caused by using delta firmware that uses segmentation with the segments too large (e.g. when trying to print faster than the electronics and firmware can handle comfortably) and/or the coordinates getting rounded to whole steps at the segment boundaries. In this case the banding should get smaller and probably less noticeable at lower print speeds.

4. A small amount of moire is normal on delta printers, although in a typical belt-driven delta it is hard to see with the naked eye using 1.8deg motors and very hard to see if you use 0.9deg motors.

Edited 3 time(s). Last edit at 03/31/2018 07:59AM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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