Wavy layer pattern
I was playing with various print settings, trying to maximize speed for a particular print, and ended up with a really interesting result. It was a single-perimeter print, and the layers started getting "wavy", and then the next layer above that would print with the same wave pattern but shifted by 180 degrees (if it were a sin/cos wave), so that the two waves essentially interlock, forming a very interesting surface texture, not to mention having a rather strong layer adhesion!
photos at: https://goo.gl/photos/erB1JdxfyjC6V8hA6
This was with a black esun PETG printing at 250, with no fan and ~30mm/s printing speed. It was basically a smallish (~15-20mm radius) single-walled cylinder. The pattern didn't appear over the entire surface of the print, just in select areas.
I was curious if anyone had seen this before -- or if anyone has found a good way to actually cause this to happen, because it's a really neat effect. I wonder if you could intentionally print a wavy first layer (i.e. the gcode actually describes a wavy pattern), and then go back to "normal" layers, and have it start interlocking like this. Or maybe generate the gcode to form the staggered wavy layers all the way up.
Re: Wavy layer pattern
Oh, forgot to mention. It was at .35mm layer height and 1mm extrusion width, with a .4mm nozzle, printing as a spiral print.