Parts do not fit together

Hi out there and a Happy new year.

Printer K-8400 1 nozzle. No heated bed.

I have made some parts, AS well AS downloaded from Thingiverse.
When I print them out, They does not fit.
I have printed a box with a lid, but the inside of the box is a litle bit to fit the lid.
Is there any way to calibrate this?

Hello,

print a test cube of known size, measure it and and scale the object accordingly. Also look at the box you printed, measure it and scale it down or the lid up a little.
Also look at the model you downloaded. If there is absolutely no clearance included, it will never fit without scaling or grinding it down afterwards.

I have made a calibration cube in different sizes, and They fit.
This is outside meassuring, inside it seems like it “grows” a 1/10 of a millimeter or so.
Is there any vay to deal vite this?

Could be overextrusion. If you’re printing with stock setting, reduce the flow rate to ~75% as a starting point and temperature to 195°C (PLA) or 225°C (ABS).

Do you have a link to the box?