Inconsistent first layer height - Sometimes too high - Sometimes too low
I'm having a lot of difficulty with getting the first layer right on my 5-tool XL. The prints are always sticking, but sometimes there's a lot of squish with significant elephant foot, and sometimes the prints are high, with gaps completely through the first layer. Even if I carefully clean the nozzle of the probing tool, just to be certain there's nothing to interfere with probing, I still get some prints that are high, and some that are low. This photo is of two parts that were printed together in one job. One was at the back of the bed, in the center, and the other was right in front of it. One is too low, and one is too high.
The black filament is Prusament PETG. There's also transparent green and white PETG (other brands) and the red is Ninjatek Cheetah. All filaments are dry, and printed directly from dry boxes with hygrometers showing 10% humidity. I have the latest firmware and PrusaSlicer 2.7.0 with the IS profiles and 0.6mm nozzles.
I measured the flatness of the bed with an aluminum bar and a dial indicator, and I don't see any flatness deviations over +-.005" (~0.13mm).
Any thoughts on what might be going on and how to troubleshoot this further?
RE:
Some XLs like mine have a major issue with the back 1/4 of the bed not being level. I was having this same issue until I found that out. Try printing a small test print in each corner (perhaps a small flat cuboid). I think you may find the answer there.
Specifically, my back left corner is way too low leading to the issue you show, while my back right is slightly high leading to excessive squish and squeezeout.
Brand new to 3D printing and my 5-tool XL is my first 3D Printer!Check out my Multi-Tool fork of PrusaSlicer to mix and match nozzle sizes.
RE: Inconsistent first layer height - Sometimes too high - Sometimes too low
This looks like what I'm seeing. Some areas of the bed are much better than others. However, if I print something that covers the entire bed--especially in PLA--the bottom layer looks fine. So maybe there's something about the exact area that it probes and there are corner cases where it can't correct for the local distortion, but it can for the entire bed? That doesn't make much sense, but I don't have any other explanation.
RE: Inconsistent first layer height - Sometimes too high - Sometimes too low
This looks like what I'm seeing. Some areas of the bed are much better than others. However, if I print something that covers the entire bed--especially in PLA--the bottom layer looks fine. So maybe there's something about the exact area that it probes and there are corner cases where it can't correct for the local distortion, but it can for the entire bed? That doesn't make much sense, but I don't have any other explanation.
I'm running down several avenues on this one. In another thread, a user suggested changing the gcode so the bed probing is done with a lower temperature. I'm linking that below. I dropped by PLA bed probing temp to 140C and that made a big impact. A 10-minute heat-soak at 80C also helps but absolutely should not be required, so I am not convinced by this hack. Apparently "fully assembled" units have been delivered with some bed warpage/alignment issues which I am measuring with a machinist's straightedge and documenting.
Brand new to 3D printing and my 5-tool XL is my first 3D Printer!Check out my Multi-Tool fork of PrusaSlicer to mix and match nozzle sizes.
RE: Inconsistent first layer height - Sometimes too high - Sometimes too low
That wouldn't surprise me--especially on a printer this large. That was the takeaway from my review of the first version of the QIDI X-Plus3. As the heat soaked into the frame during the print, the Z height changed significantly and wreaked all kinds of havoc. That's a different situation, but big beds are hard.