LR3 Y-axis accuracy off by 5mm?

He was moving his machine 3mm less if he sends 1780mm

I use my machines home location after pulloff to be the zero, and i place my spoilboard accordingly. I dont loose any space (in the v1 calculator i use 12mm extras for x&y

Now, ge solves his issue by adjusting the steps per mm, i guess we all need to fine tune things depending on what belts where in the hardware pack (its not your issue)