Why printing speed varies from one group of layers to another?
Dear community,
Would be great if one could explain and help me to fix the following issue. I have noticed that Prusa v2.6.0 uses different print speeds at different heights without (IMHO) any good reason. On the picture the speed varies from (roughly) 35mm/s (green) to 55mm/s (yellow) and that creates a visual effect on the sides of the model.
Any ideas how to make a print more smooth are warmly welcomed!
Best Answer by Neophyl:
That looks like the result of the small perimeter speed kicking in on those islands. However without your project file its impossible to be sure.
Set your small perimeter speed to be the same as your external perimeter speed and slice to test.
The blue section on top that is really slow will be because of the Slow Down if layer time is below xx setting, under the Filament cooling section. Change that speed to match and/or change the time value to something very small like 1s and you can get that printing at the same speed too.
RE: Why printing speed varies from one group of layers to another?
That looks like the result of the small perimeter speed kicking in on those islands. However without your project file its impossible to be sure.
Set your small perimeter speed to be the same as your external perimeter speed and slice to test.
The blue section on top that is really slow will be because of the Slow Down if layer time is below xx setting, under the Filament cooling section. Change that speed to match and/or change the time value to something very small like 1s and you can get that printing at the same speed too.
RE:
Indeed the key player are small perimeters 🤔 which are mixing with "normal" perimeters all the time. Thanks for looking into that and pointing out the reason. It is possible to redefine what is "small perimeter" (e.g. its length or square)?
P.S. The blue section on top was slowed down by me manually using the box modifier.
P.P.S. Strange, I should have attached the project to the original post, but apparently I missed that. When preparing this post I realized what was the trap: attaching file with AMF extension is silently ignored, so one needs to ZIP it first, then forum engine accepts that attachment.
RE: Why printing speed varies from one group of layers to another?
Yes pretty much all files need to be zipped. Btw an AMF is not a project file in the sense of what we need. When we ask for a project file we specifically want the .3mf saved from PS using the File>Save Project As option.
A 3mf saved from PS contains not only the models but is a snapshot of your slice. So all the profile settings, any modifiers, placement, painting etc is all included. We can slice it exactly as you are doing and look at the preview options. It makes it much easier to debug things.
As for the small perimeters setting being configurable by length, unfortunately not. Its for stuff like that I will drop back to using Super Slicer, as it has many many more options, including that one. Unfortunately the current release version of SuSi is based on PS 2.5 so you don't get things like tree supports or the new cut tools. It is being updated to merge with the latest PS 2.7 though so at some point we should get an up to date version. If you aren't using the new stuff though it can be worth it.
You do have to be careful swapping between the 2 as while they are based on the same software and many settings are the same there are several that are NOT. In fact they can actually be the opposite. The similarity can lull you into thinking they are the same.
RE: Why printing speed varies from one group of layers to another?
Thanks for update! I really meant 3MF, but misspelled. Thanks for pointing to SuperSlicer, it is really worth trying 👍