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Strange behavior in speed  

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Chop3D
(@chop3d)
Member
Strange behavior in speed

Can someone explain this to me? These are all the same layer types, so why is it changing the speed? I can't find any parameter that influences this. After a few layers, it just stops... I don't understand it at all. Of course, you can also see it slightly in the print quality.

Posted : 01/04/2025 7:54 am
Neophyl
(@neophyl)
Illustrious Member
RE: Strange behavior in speed

First of all welcome.  Secondly, we cant debug something without information.  I mean we can guess, and possibly give you a good guess but that's all it is, a guess.

To debug something properly we need your Prusa Slicer saved project file.  So slice, get the thing you are concerned about and then use File>Save Project As to save a PS .3mf file.  A 3mf saved from PS contains not only the objects you are working with but ALL the settings from your 3 chosen profiles as well as placement, any modifiers etc.  Take that 3mf file and then ZIP it up and attach it to a reply here.  It must be zipped or the forum will just silently drop it.

Your pictures don't give any context at all.  They are rather cropped too.  Your first one with blue external perimeters suggests that your external perimeter speed is set pretty slow.  It also looks like its on ALL the layers.  While your second picture obviously shows a difference between the lower layers and upper layers.  No info on if that's the same model with different settings, or if its 2 different models on the same build plate.

There are for example a bunch of setting on the filament page to do with cooling that can change print speeds.  Those are often based on layer time so can change things in non obvious ways.  Again without a project file its all blind guesswork.

 

Posted : 01/04/2025 9:27 am
Chop3D
(@chop3d)
Member
Topic starter answered:
RE:

Thanks for the response. Here’s a bit more context:

The blue image shows that all layers are the same type—in this case, 2 inner and 1 outer. The second image shows the set speed. Both green and yellow represent normal outer perimeters, but for some reason, they are printed at different speeds. As far as I can tell, there are no separate settings for this.

This post was modified 2 days ago by Chop3D
Posted : 01/04/2025 10:12 am
Diem
 Diem
(@diem)
Illustrious Member

Please save your project as a .3mf file

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

Posted : 01/04/2025 11:26 am
Neophyl
(@neophyl)
Illustrious Member
RE: Strange behavior in speed

Again, if you post a project file as requested we can check.  Also what mode are you in ?  Simple/Advanced/Expert ?  Settings are hidden depending on mode.

Also I have to ask this, are you even using Prusa Slicer ?  Blue bars for things like layer sliders are usually a sign of using Super Slicer.  

So to summarise, no info on version of software you are using, No info on what actual software you are generating the screen shots from,  no attached project file, no info on your operating system.  

Please attach the project file.

Posted : 01/04/2025 11:26 am
Chop3D
(@chop3d)
Member
Topic starter answered:
RE: Strange behavior in speed

Form-Kubus

Posted : 01/04/2025 11:31 am
Neophyl
(@neophyl)
Illustrious Member
RE: Strange behavior in speed

OK found what is causing it.  As I mentioned there are settings on the filament cooling that can effect speed.  Its a combination of your "Slow down if layer print time is below" setting and the fact you have combine infill active from the Reducing print time section.

Look at the preview and you will see that the layer print time changes depending on if a layer is printing the infill or not for that layer.  This causes speed changes as the layers are below 5 seconds to print.  One side effect of fast printers.  

Change the Slow down if layer print time is below setting to be zero.

Posted : 02/04/2025 6:40 am
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