Ah you're using a delta printer. With this type of printer it is very important to set up the right geometry in Configuration.h. Otherwise nonlinear distorsions and strange scaling problems will occur. You can test (and adjust) distorsions and scaling by sending gcode like > ; home > G28 > ; set to millimeters > G21 > ; goto xyz (0,100,0) with speed 8000 > G1 X00.0 Y100.0 Z0.0 F8000 to your printer, using some mm paper or a tape measure taped to the headbead. Test positions like (0,100,0), (100,100,0), (100,0,0), (0,-100,0), (-100,-100,0), (-100,0,0) (0,50,0), (50,50,0), (50,0,0), (0,-50,0), (-50,-50,0), (-50,0,0) and adjust geometry measures, until your positioning is perfect - i.e. your printer reproduces *all* tested positions with high accuracy. Also have a look into the G-code your slicer produces. Slicers usually offer parameters to do some (minimal) inset/outset compensations. Also they calculate an extrusion width. Printing a 60x60 square might produce gcode like this: > G1 X29.65 Y29.65 E20.9915 F5400 with .6 mm extrusion width. -- View this message in context: http://forum.openscad.org/Scaling-and-3D-Printing-Questions-tp17161p17170.html Sent from the OpenSCAD mailing list archive at Nabble.com.