3.6.0-beta.2 Pressure Advance Issue?

Bendy88 0

I think I have found a bug with pressure advance on G2/G3 moves. It seems that the extruder just quits extruding around medium sized holes (about 15mm). When I slice the model using only G1 moves I get a nearly flawless print. However, if I change the slicer to use G2/G3 moves I get no extrusion on the holes around 15 mm in diameter. If I set pressure advance to 0.0 the holes print fine, however I get all the artifacts one would expect from not having PA. I would love to include pictures, but it seems as though I do not have the pillages for that yet.

Some info about my machine and config:
It is a Railcore ii based CoreXY machine. I am printing at 200 mm/s and 10k mm/s^2 accelerations.

Potentially relevant config.g info:
; Axes
M584 X0 Y1 Z5:6:7 A6 B7 ; set axis mapping
M350 X16 Y16 Z16 A16 B16 I1 ; configure microstepping with interpolation
M906 X1400 Y1400 Z1000 A1000 B1000 I30 ; set axis driver currents
M92 X200 Y200 Z1600 A1600 B1600 ; configure steps per mm
M208 X0:320 Y0:302 Z0:345 A0:345 B0:345 ; set minimum and maximum axis limits
M566 X500 Y500 Z30 A30 B30 ; set maximum instantaneous speed changes (mm/min)
M203 X36000 Y36000 Z900 A900 B900 ; set maximum speeds (mm/min)
M201 X10000 Y10000 Z1000 A1000 B1000 ; set accelerations (mm/s^2)

; Extruders
M584 E3 ; set extruder mapping
M350 E16 I1 ; configure microstepping with interpolation
M906 E1250 I30 ; set extruder driver currents
M92 E837 ; configure steps per mm
M566 E2000 ; set maximum instantaneous speed changes (mm/min)
M203 E3600 ; set maximum speeds (mm/min)
M201 E5000 ; set accelerations (mm/s^2)

; Kinematics
M669 K1 ; configure CoreXY kinematics

;Input Shaping
M593 P"ZVDD" F65 ; use ZVDD input shaping to cancel ringing at 65Hz

;Pressure advance
M572 D0 S0.02 ; set extruder 0 pressure advance

This was also a problem in 3.5.4 except that I had the same issue even with G1 moves around medium sized holes. Additionally in 3.5.4 it seemed like input shaping was not applied to G2/3 moves. Based on my limited testing it seems the new input shaper algorithm is applied to G2/3 moves which is fantastic news!

I had been tearing my hair out trying to get PA and input shaping to work on 3.5.4. After some testing it looked like input shaping was not applied to G2/3 moves so I switched to a ridiculously fine gcode resolution in PrusaSlicer to get arcs to print smooth with my newly set accelerations. (with default resolution cylinders/arcs were quite choppy!). PA still just quit extruding around medium sized holes. Then I came across another forum post stating that an issue with PA was solved in the 3.6.0-Beta, so I immediately installed, and my issues disappeared! (while using G1 moves only.) Then I attempted to use G2/3 moves to eliminate the need for the high resolution to get smooth arcs. To my disappointment, my PA issues re-appeared. This is very repeatable.

droftarts

@Bendy88-0 Thanks for your report. I've highlighted it to @dc42. I've upvoted your comment, which should allow you to post images (it's a spam deterrent), should they be needed.

Ian

droftarts

@dc42 * bump *

Ian

Notepad

@droftarts This might not be helpful, but some times back in beta2, I did notice if a Z-seam was placed on a corner which was filleted with a small radius, the chance for under extrusion directly after the seam was greatly increased. At the time I only assumed it was because my PA value and extruder settings was too aggressive, but it may be linked.

T3P3Tony

@Notepad Can you check to see if this is the same issue in 3.6.0beta4 please?

droftarts

~~@T3P3Tony Maybe this one is related? https://forum.duet3d.com/topic/37435/extrusion-gaps-after-arcs~~

Checked the attached Gcode, all G1 moves not G2/3 arcs.

Ian

bsilver8192

@droftarts said in 3.6.0-beta.2 Pressure Advance Issue?:

~~@T3P3Tony Maybe this one is related? https://forum.duet3d.com/topic/37435/extrusion-gaps-after-arcs~~

Checked the attached Gcode, all G1 moves not G2/3 arcs.

Ian

(OP from the linked topic) these still sound related: so far I've only tested with 3.5.2, and the problem in this topic was reported to also happen with G1 in 3.5.4. The big difference I see is that I have PA turned off completely though. I'm planning to test with 3.6.0-beta4 tomorrow, and I'll report back in my topic about how it goes.

Also hearing about issues with holes is helpful, I haven't tried printing any parts with large holes so I'll add that to my list now.