Scale problem

[Rick Osgood]

I had calibrated my TOM to print out a 20x20x10mm calibration cube almost perfectly.  However, now that I have started printing larger objects, I noticed that they print too large, more so in the X axis than the Y.  The Z seems to be fine.  For example, the 20mm calibiration cube ends up printing at about 20.3mm or something like that.  But when I scaled it up to twice the size and tried to print it, it ended up being closer to 43mm then 40mm.  I also had designed a custom part that was supposed to print at 58mm but it ended up being 64mm.  It seems the larger I go, the more skewed the print gets.  I'm guessing this is some kind of calibration setting but I haven't figured out which one.  Any ideas?

Thanks,

RickO