Causes for bad print finish?
Hey there,
I have recently bought and assembled the Prusa MK3S and have already printed a few nice pieces. Yesterday I tried to print the rotating rings from here: https://www.prusaprinters.org/prints/7876-rotating-rings-toy
As you can see from the picture below it did print quite well except for the last few layers. At each ring the filament seams to seperate at the edges and especially in the middle it is pretty messed up. Am I right to assume that the parts may have become loose from the print bed in the end? If yes, what would you suggest to change for my next print? Maybe use some glue next time, although this should not be really necessary for PLA? Or is there any other possible reason for the bad print quality in the end?
BTW, I used the gcode from the project linked above and printed on a powder coated plate. I have also configured my first layer height and I am pretty confident, that this should be fine.
RE: Causes for bad print finish?
That part is tricky to print - most print-in-place designs take some setting tweaking to make right.
Can't speak to your first layer, but it does look like your print completed without loosening from the bed. Would have to see the bottom side to make any comments on your live Z.
Notice that the loose strands are kind of taking short cuts around the corners. I would think you want to make sure to up your extrusion width or change your nozzle temp until the traces are sticking together. The other thing you have to do to make print-in-place designs more reliable is to detect bridge overhangs and I often change my bridge speed to go 5 to 10mm slower when printing bridges.
RE: Causes for bad print finish?
I think in general it's better to start with a 3mf file or with the STL rather than the GCODE. The gcode may or may not work for your particular filament and printer but if not, you're stuck.
Actually, looking at the picture again... I thought I was looking at the model from above but now I'm wondering. These strands of filament look to me like what I'd expect to see from a print that needed support but didn't get them (filament printing in thin air). Are we looking at the side that was on the bed?
RE: Causes for bad print finish?
Assuming what you're showing is the underside... I just looked at the gcode in the Prusaslicer preview slicer, and the outside perimeter lines seem a bit smaller than what I get when I slice the 3mf. So maybe the gcode was produced with a smaller extrusion width, and the outside perimeter lines of the second layer don't have enough support and sag.
I'd reslice the model with your standard settings and give it another try.
RE: Causes for bad print finish?
Thank you both for your replies!
I did some testing this afternoon. I sliced the 3mf file myself and also reduced the overall print speed for the first few and last few layers by 25 %. This was enough to significantly improve the overall quality as you can see below.
