We're looking at the light gray cylinder and the print is upside down (you see the slight flaring from a too tight 1st layer in the top left corner). It's a 2.5cm cylinder and was printed on a bed with other parts. The first 2/3 of the cylinder are printed nominally at top speed ( 50mm/s with no perimeter underspeed) and the last part of the print (the bottom of the image here) was slowed by S3d to, say, 5mm/s since by then this was the tallest part on the bed and it was trying to maintain a certain layer time. At "high speed" I'm wondering if those vertical bands are: a) "ringing" as the nozzle changes direction to follow the vertices of the STL mesh? b) some weirdness relating to 8bit electronics struggling with curves at speed: http://forum.e3d-online.com/index.php?threads/jerky-xy-motion.1047/ ? Or something else? It's not a massive effect but a simple form like this is a good place to analyse it and the knowledge will be useful elsewhere. The second image shows the cylinder on its side in S3d. You can see the Mesh. The mesh seems to be rather finer than the banding. Hmmm. So ringing? We see that slowing it down solves the problem, but who wants to do that? So if I reduce the weight of the print head (Pro Box: Titan / pancake motor) what effect will that have?