My ultra resolution objects are growing a beard

#1
I'm only a month into using my gMax. So I'm still running tests to sort out its capabilities from its limitations. I ran an experiment overnight to compare the surface quality of an object printed using the standard 0.20mm layer height against one printed using 0.08 'ultra' resolution. Once again, both prints were sliced using S3D's Vase Mode.

First of all, the ultra resolution's overall surface quality is magnificent. (See the image below.) I'm using Hatchbox's transparent red PLA. The sheen coming off and through the piece reminds me of the first time I saw the deep red paint job on a Tesla 'Signature Series' Model S.

But there are flaws in the finish: a beard-like fuzz along the outside surface. The fuzz is most prominent at about 5:30 and 11:30 (160-175 degrees, and 340-255 degrees, for you geometrists in the audience.) The geometry of the test piece has a wave pattern. On close examination, it does NOT appear that the fuzz is due to the bead of a layer not laying on top of the layer below. Each layer seems intact. (Though at 0.08mm resolution, it's hard to say with any certainty.) Rather, it seems like extra material may be building up on the nozzle to the point that it gets caught on the surface at these points and gets deposited on the piece as the nozzle passes by.

Just to name it, the nozzle moves counter-clockwise in S3D Vase Mode.

Anybody seen this before or have any thoughts on what might be causing it. I'm stumped as to what experiment to run next to further clarify the cause.

- Bob
 
#2
If you see stuff building up on the nozzle tip, then change your extrusion multiplier by 2-3% test again...

So for PLA, you can vary from .9 to 1.0 on S3D.
For instance my hatchbox solid colors seem to be around .98, but the translucent seems a little less viscous.