Dimensional inaccuracy
When using my MK3s after it being inactive for a while, my prints are always 1mm too small in the X and Y directions. It doesn't matter how large my print is. 10mm becomes 9mm, 50mm becomes 49mm. I have factory reset, recalibrated and checked my printer mechanically. When extruding 100mm filament, it actually extrudes 100mm filament. At the moment, I'm a bit lost. Anyone had this problem before?
If you review older posts you will find many variants of this question.
Basically: Every print and every printer expand and contract as they heat and cool - it's possible to predict some of this but in practice if dimensional accuracy is essential then the only two courses are 1. to print oversize blanks and machine to fit and 2. Calibrate: print one, measure, back calculate the gain and incorporate it into the original CAD, rinse and repeat until satisfactory.
Two thing to bear in mind: Your closest limit of precision is roughly half an extrusion width, 0.225mm with a standard 0.4mm nozzle.
It is normal for thermal contraction to be greatest along the line of extrusion, depending on the model geometry this might not be in either X or Y direction but may be somewhere in between.
Cheerio,