I just made a remix of that mod to have a more rigid chassis for Z axis.
While the parts are a little too heavy to my taste, I did import the STL to FreeCAD and made some adjustments before printing. I noticed weird defects on the layers in the range of a hole. It seems that all the layers belonging to a hole have a small offset, and sometimes the part is literally sliced, like for the layer tangent to the bigger hole (8 mm diameter) or the small hole (3 mm) on the left of the picture where I can see through the part (!)
That part was printed without any support on my CR-X and I noticed that the mirrored part printed in a different position has the same defects on the same layers, so I doubt if can be an issue with the hardware. The slicer is Cura 4.6.1. It takes 6 hours, so I did not watched it and cannot tell if the print is making a pause at some points (I suspected the minimal time for a layer setting for the smallest part, but it is probably not the case for the biggest hole).
Do you know where these weaks could come from?
Here is some additional info to help for the diagnosis:
- one proposed explanation is clogging, but i think it is not the case for the following reasons:
- I replaced the stock spool holders by ball bearing mounted holders from this design (no issue to print it) and the general setup (after the chassis mod - so is was less rigid to build the part of my question) is now this one, the parts mentioned in my initial post being the ones used to mount the threaded rods so the resistance to extruder steppers is minimal
- as told, I printed for the chassis mod 2 x 2 parts from 2 initial designs, and the mirrored part for left/right sides, the defects are quite identical (same Z layer) in each pair of parts, while the mirrored part was turned is a different rotated position around Z axis, but in different layers between each pair (not the same distance from bed). Here is an example of the top mounts for threaded rods (and I remark there is a slice in the middle of a hole, not tangent to it)
- I managed to print additional pieces without issue and with satisfactory aspect and no defect at all e.g a improved part for my coffee machine (right of picture) 110 mm diameter / 12.5 mm height
The black parts were printed using basic PLA, 0.15 mm per layer, 190 (or 200 ?) °C for nozzle / 60 °C for bed, 60 mm/s with 8 mm long & 70 mm/s for retraction (and possible Z hop while retracted and during layer change). I am unsure because I did not keep this Cura project but these are my usual settings for now. I have only the machine for a few weeks.
Also: I have checked the belts but they seem neither too loose nor too tighten, while it is difficult to get an accurate idea of the tension. I would rather suspect a Z axis problem (for the slices), but it is driven by dual square threaded rods.