(really) Lots of artifacts on curves
Hello,
My 3 month-old MK4 is driving me nuts on curves. There is almost no way I can be sure to get a "proper" curve without random artifacts (dots) creeping in. Here are a few shots of my last print, but the problem is (almost) always present on anything curved.
I'm using PrusaSlicer, if this could be useful.
First, the parts on the build plate.
Close-up of one of the small upright parts. Half of the semi-circle is okay, smooth and the like. The other half is spiked everywhere. When the printer prints each layer, it goes quite fast on the first half (the smooth one ; the hotend goes left to right then) but makes a lot of small stops on the second half (hot end going right to left), and thus splotches.
Same problem on the bigger part, but not limited to half of if. Pure hypothesis : this may come from the fact that it's a real circle here, whereas the smaller parts have a straight line followed by a half circle.
Close ups of one of the small parts, where the "good vs bad" zones are easy to see (it's the same printed part on both shots) :
Those spikes also appear on the inside of the curves, here from the big long piece (this make screwing the opposite part (not seen anywhere here) somehow harder, obviously) :
And here with one of the small parts (because of tight clearance, this part is unusable) :
Does any of you have some idea where those artifacts could come from, and (more importantly) how to make them disappear ?
Thanks.
RE: (really) Lots of artifacts on curves
Looks to me like a random seam position. Printer does an outside loop, where the loop comes back to meet itself, you get a tiny blemish, this is happening in random places. I've not found a way to completely eliminate but it tends to look better if you have a line rather than random.
See https://help.prusa3d.com/article/seam-position_151069 for more details
RE: (really) Lots of artifacts on curves
Hi, thanks for your answer.
Looks to me like a random seam position. Printer does an outside loop, where the loop comes back to meet itself, you get a tiny blemish, this is happening in random places. I've not found a way to completely eliminate but it tends to look better if you have a line rather than random.
See https://help.prusa3d.com/article/seam-position_151069 for more details
That was one of the first idea I thought of. Unfortunately, it is not the seam. I haved "seam : aligned" configured in PrusaSlicer. Moreover (but it's hard to tell from the photos), I have several dozens of "bad points" on the same layer.
RE: (really) Lots of artifacts on curves
When it's on one side like this, there's a couple of ideas I have:
1. is it occurring when the print fan is blocked by the part? So maybe it's wet filament but on the cooled side it solidifies before bubbling, but if it takes longer to cool it bubbles then solidifies
2. asymmetric belt slippage - not sure if this is a thing, but can the y or x axis belt be slipping only when it is moved in one direction but not the other? Maybe it's moving in the end fixation or something. On second thought this seems unlikely to cause what you're seeing...
Prusa MK4 since Jan 2024, Printables: @MikeB_1505898
RE: (really) Lots of artifacts on curves
This looks like the old buffer problem where the printer can't keep up with loading commands, so it pauses constantly.
Are you using .gcode or .bg format?
Are you loading the gcode from USB, PrusaConnect, or OctoPrint?
Do you have G2/G3 commands enabled?
RE: (really) Lots of artifacts on curves
Hello,
This looks like the old buffer problem where the printer can't keep up with loading commands, so it pauses constantly.
Are you using .gcode or .bg format?
Are you loading the gcode from USB, PrusaConnect, or OctoPrint?
Do you have G2/G3 commands enabled?
I'm using the regular Gcode format, and going through octoprint. I'm going to make some tests with a USB key, hadn't thought about that.
As for the G2/G3... I do not know how to activate them. Looking at the Gcode, the « offending » areas only use G1.
RE: (really) Lots of artifacts on curves
G2/G3 commands can be enabled under Print Settings -> Advanced -> Slicing -> Arc Fitting -> Enabled: G2/3 I J
RE: (really) Lots of artifacts on curves
Hello,
G2/G3 commands can be enabled under Print Settings -> Advanced -> Slicing -> Arc Fitting -> Enabled: G2/3 I J
Found it, thanks !
So far, my tests are... well, as you can imagine. Everything works perfectly, even without G2/G3 optimization (i.e. the very same file that prompted my firs post, on the same printer, without anything having changed except we are on a saturday).
So I'm currently leaning towards an outside cause, for example bad USB cable (it is a longer-than-useful cable). I'll keep investigating, if/when the problem arises again.