Layers go bad when cross-section changes abruptly
I have a problem printing models where horizontal cross-section changes abruptly. A simple example would be multiple boxes or pillars of different height. At the Z level where one pillar ends, there is a change in layers of other pillars. Sometimes I just get a very weak bond, other pillars are weak and may even snap at the exact height where the cross-section area dropped. Sometimes it's as little as a visible line across all other pillars at the same height. Sometimes it's few ugly layers, uneven or sticking out sideways. But somehow, when the total print area changes abruptly from one Z value to the next, the layers at that next Z (the first layer printed with the smaller area) are always affected.
This happens with both ABS and PLA.
Any suggestions?
Thanks!
Re: Layers go bad when cross-section changes abruptly
I have a problem printing models where horizontal cross-section changes abruptly. ....
Any suggestions?
❓ which slicer ?
❓ which resolution ?
❓ which amount of infill ?
❓ how many top layers ?
❓ can't you provide some pictures ?
it's very hard to figure out what you are exactly concerned about...
dem inscheniör is' nix zu schwör...
Re: Layers go bad when cross-section changes abruptly
Here is an example, a spool holder: https://www.tinkercad.com/things/6lbdLUOnrI7-prusa-i3-mk2-spool-holder . The photo is attached. ABS filament. Slicer was Slic3r but I've had very similar results with Simplify3D. Printed at 0.2mm with standard settings (6 top layers, 5 bottom layers, 20% cubic infill). Temperature was 255 for the first layer, 240 for other layers to reduce warping, bed at 100 degrees.
You can see two seams in the photo. The first is exactly at Z level where the top of the horizontal base is. The second seam is exactly where the top of the rectangular fin is (the top layer between the two triangle slopes). There are seams like this on all three tall parts, the photo shows the frame mount, the same is at the spool tube, and the filament guide actually snapped at both seams when I handled the part, the layers just came apart like they were cleaved. There were no weak layers anywhere else, I superglued the guide back and nothing else breaks.
Thanks!
Re: Layers go bad when cross-section changes abruptly
Here is another example, this is PLA, 0.35mm, again Slic3r, default settings for Mk2. You can see that the outer wall is shorter than the inner walls, so at Z=20mm the cross section changes abruptly. Zooming in on parts of the print shows that starting from Z=20mm, the layers of the inner walls look different, less accurate.