zhangyx1998
commented
5 months ago This problem also exists on objects with semi-open holes and complex geometries. An example image is attached. The "holes" denoted in red lines are supposed to be shrunk instead of being expanded.
In these cases, the expansion could only be reliably calculated from the local curvature of contour paths.
LMK if you would like to investigate on this more, I would be happy to help implementing some algorithm.
BambulabRobot
Bambu Studio Version
1.8.4.51
Where is the application from?
Bambu Lab Official website
OS version
MacOS 14.3.1
Additional system information
N/A
Printer
Bambu Lab A1 Mini
How to reproduce
x1) and X-Y Contour Compensation (x2) to a different value, i.e.x1 !== -x2.Actual results
Inner surface of the layers with holes are offset from other layers. i.e. an extra "ring" was printed on the inner surface, with exactly the same heights of the through hole.
Expected results
Demonstrative Cross Sectional View:
Project file & Debug log uploads
Project file is not necessary for this specific issue.
The problem arises because the hole breaks the topology of a layer, making the inner wall part of the outer contour. The slicer would then apply outer wall expansion on the inner wall contour, which is actually supposed to be shrunk instead of expanded (under given configuration).
Sliced layers:
This is kind of the "expected" behavior according to topology, but it destroys the inner surface of the model. In my use case, I need a perfect smooth inner surface to create a sliding fit.
Possible solutions:
Instead of checking the direction of a contour line, use the curvature of the path (i.e. inward v.s. outward) to calculate the offset. i.e. Higher inward/LHS curvature corresponds to smaller hole, and should be shrunk more, and vise versa.
This should be a more precise way to model the extrusion expansion. This looks like the ideal and optimal solution to me.
Insead of offset each layer, apply the compensation to the meshed model before slicing.
Checklist of files to include