- Solution
Time for another Slashee Deep Dive™:
So the cause of your quandaries seems to be a combination Cooling > Minimum Layer Time and your acceleration and jerk settings. Minimum Layer Time is is designed to slow down layers that would be especially quick to give the filament time to set. Looking at the file you sent:
The orange lines are because of your inner wall speed is twice your outer wall speed. The blue patches on the inside of the letters are where some skin (top/bottom) is poking through and its acceleration and jerk are lower than the rest of the print. If I reduce your inner wall speed these look good, but it's not a huge issue overall:
Minimum layer time isn't coming into effect here because you're printing both cubes, which obviously takes more time.
If I switch to just the regular cube:
The middle layers are being significantly slowed down so that they take the minimum layer time to complete. The skin layers print at full speed because they need to cover the whole surface, which takes a lot more time.
Switching to the calibration cube:
The layers where the walls are printing faster is because there's some skin in there slowing it down. Where there's no skin, they need to be slowed down a little to meet the minimum layer time.
So what can we do about it? Turning down the minimum layer time would make the preview look pretty:
But that's ignoring the real problem:
Yes, the E3V3SE can accelerate at up to 4000mm/s². But that doesn't mean it's a good thing. Too fast and the filament can end up being dragged behind the nozzle rather than being laid down properly. I never go above 1000mm/s² myself (including travel speed), and even then I've found problems with support (which I print at a lower flow rate so it's a bit easier to remove) being pulled along (and out of position) when the head zooms off on a travel move, resulting in a warped print (so I don't have to slow down the acceleration the whole print I created a post-processing script which lowers the maximum acceleration when it starts printing support until after the first travel move away from the support - but you probably only need to worry about that if you share my level of paranoia).
However my bigger problem:
Umm... holy cow. I never print with jerk above 8mm/s, and go as low as 2mm/s if I'm printing something complex or likely to fall over. Jerk is how much the head is allowed to instantly change direction at corners. In an ideal world, the print head would move to a corner, come to a stop, then start to move in the next direction. In the real world, that would result in a blob at the corner, so it has to slow down a bit to approach the corner, and then at the corner instantly change direction and start accelerating in that direction. High jerk - and I'd call this ridiculously high - can also result in the print head or build plate slipping and moving a step or two out of alignment due to the vibrations. This causes layer shift, which is when layers start printing out of alignment with the ones below. It can also make the filament cut corners, seeing it's being dragged behind the print head and it'll just get pulled along and follow the print head using the shortest path possible (which will be a diagonal because it doesn't have time to set before getting dragged along).
If I disable jerk control (which will make it print with the printer's default jerk settings, which are much lower than 40mm/s) then the preview in Cura doesn't actually change, but that's because it doesn't depict acceleration along a move, just the print speed for a line.
The solution: firstly, lower your jerk or turn off jerk control. This doesn't actually make the previews look any different, but it'll immensely help the print process. Trust me. Slow print > bad print.
As for how the previews look... it's working as intended. You're printing very quickly and your layers don't have much in them. You could try lowering the minimum layer time to something like 1 second and that will make it print at a consistent speed, but that setting is there (and has a default of 10 seconds) for a reason. Feel free to lower it so it doesn't slow down a print and test it, and if it works for you, go for it. Small scale testing is your friend. Just try and remember it if you're trying a more detailed print later and having problems.
Personally I'd also turn off acceleration control (or lower it to 1000mm/s²) so the acceleration is a more reasonable pace. It's not going to change the speed in the preview, and yes it will make it take longer, but again: slow print > bad print.
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Slashee_the_Cow 489
The colour spectrum used for speed changes depending on the speed range that will be used in your print, so you can't do an apples to apples comparison, and in all three of your screenshots it's different - and hard to see because of how the forum crushes image quality:
If you could post the Cura project files of all three of your examples (.3mf, in Cura set it up then go to File > Save Project) that would be great, so we can see if there's anything we can figure out based on them.
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MrLonnie 0
Gotcha! Good to know for posting on here. I reduced my outer wall speed by almost half and it kind of fixed it visually in the slicer. I still have the issue of banding along the layers where speed changes in the slicer. I slice under my customsd_alt profile usually, but I saved the change in the temp#2 profile.
CHEPCalibrationCube.3mf
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