Dimensional accuracy - XY position - relative error
Hello,
Recently I've been printing some large models which I split into 4 or more prints and connect them like Lego with little nubs and holes.
The problem is that they often don't fit together. I'm not talking about the holes being smaller or nubs bigger. It is NOT an over/under extrusion/expansion of filament. It is about positions of those holes and nubs. The farther are two holes/nubs from each other the bigger is error in the distance of their centers from each other.
I've measured it and come to conclusion that X axis should have 100.3 steps per mm and Y axis should have 100.5 steps per mm. But how can this be? The pulley and belt have teeth so the ratio should be as designed i.e. 100 steps/mm!
Can XYZ calibration play a role? Btw. I've already tried redoing it to no avail. My understanding is that it just corrects angles not lengths of XY axes. But could there be something like rounding errors or trigonometric functions approximation that come into play?
Right now I'm running a new print with `M92 X100.3 Y100.5` and I'll see whether it helps but if anybody can provide me with any clues where this problem can originate I'd be grateful.