Does anyone know what causes these horizontal ridges, and how it's possible to reduce this effect?
I printed these stands from http://www.thingiverse.com/thing:106568.
Very simple prints, no overhang, no retractions etc. Printed at 0.2 mm at low speed (outer shell only 20 mm/s), see Cura 14.06-settings screenshot. Some overhanging ridge appeared on the first print (left), mostly on the x-axis it seems. At first I thought the whole x-plane had shifted somewhat (slipping belt?), but it appears only at one side of the print. So with the second (mirrored) stand I rotated the print 90° to see if it was again mostly the x-axis. Seems to be the case.
Also, it looks as if the z-resolution changes whenever there is a 'change' in the shape or total surface area of a layer, causing 'ridges' all over the print. If I were printing fast, it would probably be that previous layers had more cooling time. But does that still have such a big effect at low speed? You'd think there would be plenty of cooling time anyway. I'm using this fanduct btw: http://www.thingiverse.com/thing:151061
Some more pics:
I'd be grateful for some helpful tips to reduce these effects!