y slope with 3.5.0-rc1, not seen with 3.4.6

Adrian52

There seems to have been a change in the most recent prusa slicer(2.7.0alpha1) and orca slicer(1.8.0beta2) which has caused a recurrence of this problem.
A further note - trying to find the minimal conditions to trigger the slope, I found that a 20mm cube with no fill and no top layer does not slope, but the cube with fill (still no top) does slope. So presumably the problem lies in the transition to and/or from perimeter to infill.

balajiramani

I too have observed a similar issue with the 3.5.0-rc1 firmware. For me, it happens when I print a cubioid in vase mode. Printing the same stl with two walls does not exhibit the problem. I reverted back to 3.4.6 and the prints are fine.

gloomyandy

@Adrian52 If you now have a simple repeatable case I wonder if you could try changing a few things that look like possible problems to me....

I think you are only setting the jerk value for one of your two extruders with this line:

M566 X2100 Y2100 Z2100 E3000 P1

Can you try running M566 in the console to check what jerk settings you have for the two extruders (and maybe post the results). If they are not the same could you try setting both extruders to 3000 jerk. (so E3000:30000)

Your jerk settings seem very high to me and I've seen that cause skipped steps. Could you try reducing them all to something like:

M566 X500 Y500 Z500 E500:500

Can you try removing the L400 option from your input shaping command (not many folks will be setting that parameter and how it works has also changed in the most recent rc1 builds).
Can you try disabling input shaping completely.

It is probably best to try the changes individually though I suspect that item 1 is just wrong. However applying the "correct" jerk may have a knock on effect given that you are using the two extruders in tandem as I think that will now allow the very high jerk settings you have to be used (at the moment I think may be limited by the default jerk for extruder 1).

I understand that things worked fine in 3.4, but some of the changes in 3.5 (in particular some of the changes to IS) may mean that things like the high jerk settings are now causing problems that would not have been triggered in 3.4. I'm also not suggesting that for instance you run with IS disabled or that the suggested jerk values are the final ones, it it more a case of exploring possible causes.

Good Luck!

Adrian52

@gloomyandy Thanks for looking at the problem.

the output from M566 is

22/11/2023, 14:21:15 	M566
Maximum jerk rates (mm/min): X: 2100.0, Y: 2100.0, Z: 2100.0, E: 3000.0:3000.0, jerk policy: 1

So that jerk command I have does seem to set both extruders.

I will try a lower E jerk setting
I played with the L parameter at DC42's suggestion, because with 3.5 I was getting very hesitant movement of the extruder, leaving lots of little loops on the print surface. This was the minimum value that gave fluent movement and a smooth surface.
I should have mentioned that I have already disabled IS, and still get the y slope

Will report how lower jerk looks

Adrian52

@gloomyandy with E jerk at 500 for both extruders, I still get the y slope if the cube is 15% filled, but vertical sides if the cube has no fill. I checked this with the release version 1.8.0 of orca slicer.

gloomyandy

@Adrian52 Did you experiment with lower jerk settings on X and Y? 2100 seems pretty high.

Adrian52

@gloomyandy not so far - can do. Didn't think they were that high for a delta.

Adrian52

@balajiramani hi - I just tried vase mode in orca slicer, and it printed vertically for me. I am using a recent 3.5rc1+ (from 2023-11-1), so that may be the difference .

Adrian52

@gloomyandy just tried with 900 x, y, and z jerk. The y slope remains the same. I originally tuned the jerk up to 2100 to control sharp corners bulging.

balajiramani

@Adrian52 Can you point me to the link where I can download the 3.5rc1+ firmware for Duet Wifi? I would like to try that out.

Adrian52

@balajiramani I think this is it
https://forum.duet3d.com/post/326478

balajiramani

@Adrian52 Thanks for the link. I will give that a shot and report back.

balajiramani

@balajiramani I tried the 3.5rc1+ firmware and the slope is no longer there.

Adrian52

@balajiramani is a cube with 15% fill vertical for you?

balajiramani

@Adrian52 Haven't tried that specifically. Let me try that and report back.

balajiramani

@balajiramani I just tried a cube with 15% infill (not sure how much that matters) with the 3.5.1rc1+ firmware. The slope is back. I am reverting back to 3.4.6 for now.

Adrian52

@balajiramani phew - glad it's not just me. I find zero fill (and no top) prints vertical - not tried other fill levels.

balajiramani

@Adrian52 Are you using vase mode or regular mode with zero infill and no top surface? When I use vase mode for a cube that is longer in the X direction as compared to the Y direction, I get sloped prints. If the cube is longer in the Y direction, then it prints fine.

Adrian52

@balajiramani I have been using regular mode rather than vase mode. Will check out varying x:y ratio with no fill on my setup.

Adrian52

@balajiramani
tried with unfilled cuboids, with 3 perimeter walls :
30x20x20 (x, y, z) - very pronounced y slope, about 1.3mm over the 20mm z height.
20x30x20 - y slope almost gone, but still clearly there; about 0.3mm over 20mm z.
20x20x20 - rechecked this with exactly the same slicing as above, printed consecutively, and it comes out vertical.
What??