I printed a model today with some pretty severe under extrusion (3/16" gap, see pic #3) at the seam. Looking for ideas of what caused this and how to avoid it. I know how to print and never get under extrusion. This seems to be something in the slicer. See the pictures as they tell pretty much the whole story.
1 - The model face in question is continuous.
2 - The sliced model shows an odd shaded area which I thought was just weird dithering, but its not. (see Pic #4)
3 - The print has a 3/16 gap at the seam.
4 - This shot shows the Flow view – the reduced flow section is obvious.
Using Orca 2.1.1. Printing PLA mostly at generic defaults except Gyroid infill and support enabled. No Scarf on this one.
So I already know at least part of the answer to avoid it: Randomize seams and the problem goes away. Or more accurately, is spread out so its not noticeable. But that’s a hack – I’m trying to figure out what setting is reducing flow so drastically at the seam?
Try reducing the seem gap % to do this you will need to enable the developer tab in the preferences menu near the bottom, then under the quality tab there will be a setting for seam gap, reduce it to 10-12 % and try it may need to be a little bit lower. I have found that I need to do this with some filaments.
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The photo in the bottom right clearly looks like the [scarf seam] setting is active, which would slow down the flow prior to the end of the seam.
when thats active in orca slicer you’ll need to have a the paired setting [extruded flow rate] - I can’t remember the name clearly… but its at the very bottom of the [Speed] settings tab. A value between 300-350mm/s^3 is desirable and will smoothen the gap as it’ll adjust the flowrate accordingly.
OR this could be an issue within the model itself because it should slow down there.
After testing found that you’re right, scarf is the source of the issue. The flow rate at the beginning of the scarf drops to zero and that is causing the gap. I’ve been adjusting settings for outer wall speed and scarf speed and length, but nothing has changed this much. Its odd because I’ve been using scarf defaults for a few weeks now with no issue. Based on @oddsandsods comment I’ve enabled Scarf Joint Flow Ratio and am testing that now. I’ll try Extrusion Rate Smoothing (assuming that’s the speed setting you were referring to) next.
The developer setting exposed Scarf Joint Flow Ratio. I already played with Seam Gap a bit and didn’t notice much change, but will test some more with both of these.
How’d it go? Typically itll be the extrusion rate smoothing flow
Yea, I don’t know. I spent hours messing with settings, but nothing made any difference before I ran out of time. My seams, any type, are big gaps. I think I wasted a lot of time trying to determine if the issue was in the latest Orca betas or scarf properties. Later today I’m going back to basics – thinking maybe its just new filament retraction and PA settings are off. I really never mess with these since moving to P1S, but if I were still on a last-gen printer, that’s what I’d say these big craters are.
Yeah it could possibly be caused by retraction, I had an issue with PETG getting holes after a seam and reducing the retraction to about 0.4mm fixed it. Try reducing it and see if the holes close up. You can check the standard retraction length in the printer settings but to alter them the override settings are in the filament settings under the override tab if you’re unsure. Don’t alter them in the printer settings as this will be global to all filaments and could cause you major problems, I’ve been there😂
