Trapezoids? I have a 50mm square test piece (50% scaled from http://reprap.org/wiki/Calibration#Theory_and_Maths) and while I’m much closer (50x50mm printed as 57x55mm, now 50.1x50.7) I’m obviously taking an average because I’m NOT PRINTING SQUARES. 
The object is centered on the build platform and I’ll blame my crap effector (with the aforementioned drag issues) without the slightest provocation…but man, how do you compensate when squares aren’t squares?
Is this a mechanical issue? I assume if you try printing a circle you get an oval?
he stepps are set correctly?
I’m thinking it’s drag on one of the effector balljoints, or the printers not quite dialed in. I’ll reprint, then measure in place and see if the geometry corresponds to one of the three towers.
@Wayne_Friedt That’s what I’m tweaking to get the printer calibrated (so 1mm in the model is 1mm in real life), unfortunately, if you change e-steps, you have to recalibrate EVERYTHING, with the added hassle that the end stops only have so much adjustability in them.
'Getting real good at it, though, just not good enough.
Use a firmware with M206 /M666 adjustments to speed up recalibration
I’m getting good enough at dialing it in, I just may do that.
Mike you’re using a 3DR yeah? I get the same thing.
There’s some wobbling of the extruder in the mount, I’m thinking based on the direction of extrusion and that deflection it’s causing the nozzle to drag about a bit.
Do you have 6mm rods? I’ve noticed that though I’ve resolved the bearing slop I get a bit of flex in them causing slop.
Same here too. I’ve found that my rails are not square - bottom motor mount and top electronics mount differ dimensionally and so the rails are not parallel, they are closer at the top. There’s a lot of discrepancies in the dimensions in the original Sketchup files which seem to have been compounded with differences when printed. I’m going to dismantle mine and try shimming the top mounts to bring it back in true.
