I have noticed when slicing and using variable layer height, that it will override any speed settings at any layers that are very thin.
IE: I’m slicing a curved part using PETG. Slicing it before adaptive layer height applied, the layers all have consistent speeds and it prints fine (albeit with visible layer lines). When I use adaptive layer height to smooth out those layer lines, then slice, the gcode output for the thin layers has overridden my custom speed settings and prints way too fast. This speed increase ultimately causes the print to fail. Images of both examples (In described order) below
With custom speed settings you mean line speed as opposed to volumetric speed, right? So what are your settings? What line types are indicated in the preview for the lines that print too fast?
It looks like you have your speeds set to 300 mm/s but with regular layer height, it can’t reach those speeds, because max volumetric flow in the filament settings throttles those speeds down. With adaptive LH, the thinner layers can be printed much faster before the flow limit throttles.
You could quickly test that slicing without adaptive LH, but regular layer height reduced in half. I guess that now you see the same high speeds.
So if you want consistently lower speeds, reduce the values in the speed setting tab of the process settings to the desired value
As @Alex_vG has pointed out, it looks like you are hitting your max volumetric speed in some regions and your line speed in other regions.
You could try to uncheck the “Slowing printing down for better layer cooling” in your filaments settings. This should resolve your issue. However, keep in mind, to ensure ensure propper layer bonding and printing details in those regions, it might be beneficial to reduce overall print speed.
