Printing Polymaker PLA Pro, at 215C. High Temp plate at 55C
When printing small parts (or short sections of larger parts), I get exceptional print quality. On larger parts, the quality degrades on longer runs, getting worse the farther the nozzle travels without interruption. In the image below, the semi circle is about 7 inches in diameter. The layers where features/holes break up the layer, I get really good quality. The top and bottom, where there are long, continuous paths result in degrading quality. You can see the quality gets worse the farther the nozzle travels (left to right in this case).
I’ve confirmed that this is not dependent on bed position. The opposite side of the part shows a mirrored result, with the quality getting worse from right to left as the nozzle moved that direction on the other side.
I’m quite stumped by this. I will try lowering the nozzle temperature a bit, and maybe the max volumetric flow rate. Would appreciate any other thoughts.
I think you idea about reducing the max volumetric flow rate might be on track. It does not matter what the max speed or speed setting is for a short section because acceleration and deceleration take up part of the section. For a long enough section the nozzle will reach the max speed set for that kind of extrusion and limited by max volumetric flow rate. If your max volumetric flow is set just a little high then the only time you would see the under extrusion is when it runs at max flow for a long enough time.
I am no expert on this. But I agree with you that it only shows on long contiguous extrusion and it looks terrible. Good luck!
The quality difference is noticeable between the layers with openings and others.
Check the sliced print layer time, flow and speed. Or share print screens including this info.
I expect the quality issues will be noticeable in the sliced print.
One more vote for max volumetric being too high. You could increase your extruder temp, though, and that would possibly address the issue too.
The printhead doesn’t run at full speed all the time. It has an acceleration parameter that dictates how hard it tries to get to speed. For the runs between the holes, the printhead is almost certainly not getting to the same high level of speed it gets to on the uninterrupted run, which is why you see it there and nowhere else. That’s the area where acceleration has the most time to get the print head to higher speeds…
Max volumetric was the culprit. Reduced it from 21 to 15 and saw much improved results. Will experiment some more to see how high is too high. For now, this does it. Thanks again.
