Originally shared by Ursus “Dreamer” Domesticus
3D printed satellite
they are some nasty prints you got there.
WHat would be causing all those lumpy artifacts?>
I see something similar (though not nearly as bad) when printing cylinder shapes at high speed.
I think it’s caused by a slight over extrusion at the layer transition points, but I’m not 100% sure. Personally I’ve not run into it enough to try and calibrate it out, but if anyone knows a way I’d be interested in hearing it.
Same problem I’m fighting on my prints now. I think that’s the retraction but I’m not entirely sure.
Depending on the slicer you are using enabling/disabling retraction on layer changes can sometimes help with those zits too.
@Aric_Norine these don’t look like random start point blobs - they’re mostly in a consistent pattern. Look on the nosecone - they’re in a straight line up the side, appearing every X layers.
It looks more like some sort of build-up on the extruder that’s being dropped regularly when it reaches a certain “weight”.
I had a problem that was similar, tried every setting in slicr that had to do with retraction. Then i noticed there was a lot of play in my push-fit coupling for the PTFE tubing. I replaced them, bumped up the retraction to 6.5 mm x 110 mm/sec, and used wipe setting. There are still traces of this heppening but it is 10x better.
Too fast retraction i believe. Had that issue for some time now. Halfed the retraction speed and iam on now 
I’m curious what is your retraction settings (length & speed)?