How to improve corners consistency?

zapta

This question is for a new Hypercube Evolution CoreXY printer with 60cm 1.9mm bowden. The prints have issues with corners consistency. Some corners (not layer start/end) are 'inflated' and others have inconsistencies on layer that change footprint.

Any suggestion how to improve it?

The duet's config.g file is here https://github.com/zapta/misc/blob/master/evo/duet/sys/config.g , slicer is Simplify3D.

If it matters, this is the model colored in Simplify3D by head movement speed.

Veti

https://duet3d.dozuki.com/Wiki/Pressure_advance

and

https://duet3d.dozuki.com/Wiki/Gcode#Section_M592_Configure_nonlinear_extrusion

zapta

Thanks @Veti, I will try to digest the information.

Can the inflated corners be related also to jerk setting?

Phaedrux

Usually I find that bulged corners or edges like that are a result of either xy jerk being too low and slowing down too much on corners, or z axis speed or retraction speed too slow/E jerk or acceleration too low causing layer changes and retractions to take too long and allowing plastic to ooze out.

Looking at your linked config file I would say that your E jerk and acceleration are quite low and you could increase them by an order of magnitude.

Pressure advance can also help quite a lot because it reduces nozzle pressure in advance of the nozzle speed reduction which helps keep the extrusion width consistent.

zapta

Thanks @Phaedrux , this is very useful. I also found your post here https://forum.duet3d.com/topic/8689/extruder-acceleration-jerk-and-tuning/3 and quality is much better now.

Findings so far:

Turning off Simplify3D "Adjust print speed for layers below..." significantly improve consistency between layers as they are printed in same speed.
Various pressure advance settings don't change the corner bulges. Not using it.
Corner bulges appear more when printing in high speed. Increasing jerk limits significantly improve it.

My current setting is based on your other post but with increased jerk limit:

M201 X6000 Y6000 Z30 E8000                              ; Set maximum accelerations (mm/s^2)
M203 X15000 Y15000 Z300 E15000                          ; Set maximum speeds (mm/min)
M204 P1000 T3000                                        ; Set printing and travel accelerations
M566 X1200 Y1200 Z100 E3000                             ; Set maximum instantaneous speed changes (mm/min) (Jerk)

dc42

@zapta said in How to improve corners consistency?:

Various pressure advance settings don't change the corner bulges. Not using it.

That's unusual. What values of pressure advance did you try, and how long is the Bowden tube between the extruder drive and the hot end?

zapta

@dc42, 0.1 to 0.5 with 600mm, 1.9mm ID bowden.

Another change that improved the corners was reducing temp from 215 to 200 (PLA). The corner are reasonable now, especially at lower speeds, but not perfect (coming from a direct drive Flexion printer).