For the z axis you just physically measure. Tell to to move 100 and check it with calipers or print a 1oomm tall part and see what happens.
Turns out it was just the one crappy bed I got from a crappy printer, Doesn’t happen with any other bed I have tried. If you want to be extra safe add a fan to your ramps or a heatsink to the mosfet parallel with the d8-10 block (or both).
Rods are on order but my vendor just switched my rep and she isn’t very good at her job, normally I could give a time frame but she hasn’t even shipped my first order yet, and the rods are on the second…