Thin-wall printing bug

[gdmccormack]

Scenario:
Start with a solid model, which is then shelled to the nominal width of the print extrusion. The CAD software's shell algorithm will adjust according to the slope of the surface, so that sloped walls will have a thicker linewidth when sliced by S3D. Setting thin wall behavior to "allow single extrusion walls" will accomodate the thicker linewidths for sloped walls, however a bug occurs when the extrusion goes from printing a vertical wall to a sloped wall. In the attached image, endpoint modifications (like wipe and endpoint extension) were turned off for clarity in the S3D simulation screenshot. In the printed result the otherwise pristine surface can be turned into a hot mess from all the unnecessary extrusion stops and starts.

Any suggestions on how to stop this? I admit I'm mystified why the toolpath algorithm thinks its a good idea to stop an extrusion, only to restart it at the next index position. I go through a lot of time and effort to create designs that hide the extrusion start/stops, and this vertical-to-sloped wall issue really compounds the difficulty.

[S3D-Alex]

Could you please post a Factory File for this so we can look into it further?

[gdmccormack]

Thank you for looking into this!

I've attached the factory file for a 'torture test' of the undesired stop/start effect, which might help understand what triggers the issue. There are two adjacent shells that have a narrow gap cut in their facing walls, to force the desired location for layer indexing.

Each structure has variable radiused corners that start at zero at the base. The upper radius is 0, 0.8, 1, and 2mm for the square structure, and the upper radius for the rectangular structure is 1 or 2mm for walls sloped at 45deg and a slightly curved 30-ish degrees. You can see many undesired retractions along the radiused corners. I haven't found any combination of settings that can eliminate the undesired retractions.