Hi everyone! Can anyone point me in the right direction on how eliminate the different surface sheens I’m getting when printing with PETG? (Brand is OVERTURE).
Is this a cooling issue? I included some photos below.
Can’t tell if that is flow ratio problem or a max flow/speed problem. If its a flow ratio problem, run some flow ratio calibration tests and tune it in.
If its a max flow rate/speed problem its all about print speed and flow. The printer can print faster than the hot end can properly melt the filament. Slow the speeds down and get a more consistent sheen.
Adversely, you can sometimes mitigate it by bumping up the nozzle temps to help melt the filament more evenly and fully. But the best way is to manage the print speeds.
The best way to do this, look at the flow preview in the slicer. As shown below, I would have a change in sheen when it goes from 80mm/s to 200mm/s (cool how the software can predict this to the layer). The two ways to clean it up is to either limit the max flow in the filament profile, or slow down the outter walls to a similar slow speed (for example in my example of 80mm/s and 200mm/s I’d want to keep the outer wall speed down to 90mm/s and lower).
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Hi, I appreciate the input! See below for flow, speed, and fan speed of this object. They are pretty much constant throughout the print, other than the first layer which is not the layer I’m having an issue with.
I’m still thinking the speed of the top wall could be playing a part (because its pushing along pretty fast on that layer).
Try a test, cut it in half and scale down the Z axis by 50%. Try one as you did it on your first print, as a control (basically to make your the problem repeat), and one with the top surface max speed dropped to 100mm/s. I’d test to see if the speed is boarder line.
If it is a flow ratio issue (over extrusion), simply run the flow test on Orca Slicer.
This looks like bad PA with a slight underextrusion.
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I missed how much detail the OP’s pics had. You may be on to something with the PA. If you look and the entire extrusion line you can see a VERY pronounced extrusion change in the area the OP is unhappy with. Can’t tell if its the acceleration or deceleration which is significantly crushed down. But looking from left to right the extrusion lines get significantly flattened and the sheen changes.
OP, did you change the pressure advance settings?
Hi, this is PETG but I don’t think that matters much.
Forgive me as I’m still only a few months into 3d printing (I am well experienced with CNCs and lasers).
I have not changed any of the pressure advanced settings. Isn’t that what the flow calibration is for (X1?). Either way, what settings in Bambu Slicer should I be looking at to dial this in?
Pressure advance is important to all filaments if the printer is trying to account for it. PETG is actually a relatively difficult filament to print well. People tend to classify it as an easy to print filament but, at best, its in the medium ease of print range.
The pre-print calibration should fix this, but obviously, in that photo its clearly not. In the picture below, you can see the printer start the lines one way and finish a completely different way. This is consistent with an incorrect pressure advance setting. Again, ideally, the printer should be able to account for this but it looks like it not coping well. These lines should be consistently thick as the print accelerates and decelerates through its range of motion.
Do you have Orca slicer downloaded? If so, run the test for pressure advance and manually calibrate it with the slicer tool. And try again.
If you don’t have Orca, try a print with the pre-print calibration turned off. Maybe its actually making the print worse, with a bad value.