Welcome to the SeeMeCNC Community

My parts are shrinking in the X and Y as is goes upwards in the z-direction. it appears to be fairly consistent - about .5 of shrinkage per 50mm of height. it does not appear to get more extreme if the part is wider, so I figured it's not the delta_radius / arm_radius, but I don't really know. The adjustment I made in that area just messed up my perfect bed calibration and didn't seem to fix the scaling.

I've had this problem forever and until recently I was rarely making parts that needed the precision fit that high up, but now I'm in need of a fix. thanks for the advice

Is your tower spacing exactly the same at top and bottom? A larger spacing at the top would cause shrinkage with increasing height. If it's not that, maybe it's something to do with heat rising from the bed.

yeah. tower tilt is my theory as well. I've never messed with it myself. it's been exactly as it came from seemecnc - accept that it has traveled a bit. I'll go find a way to measure that and see.maybe a tight cord around the top would make enough of a difference to do a quick test?