I think it’s in this thread.
This script is intended to tell you where your limits of accuracy are based upon the dimensions of your frame. It’s not really intended to tell you if your machine will produce straight or curved lines.
The accuracy of the maslow depends upon the kinematics model the controller uses to convert x,y coordinates to chain lengths. If the model doesn’t account for all the equations that govern the system (i.e., chain sag, chain stretch, wrap around sprocket, etc.) or use the correct coefficients for those equations (i.e., the calibration parameters), then results won’t be as intended. It’s hoped that holey calibration kinematics model will get us closer than the current model and that we can achieve accuracy high enough that it doesn’t really matter how ‘straight’ a line is. In reality… and this might be a bit deep… with how the machine works, every ‘straight’ line will really be some form of an arc… the goal is to use the kinematics model and calibration such that the curvature of the arc produced is as close to zero as possible. If a straight line from one side of the board to the other results in an arc with a 0.5 mm curvature (its 0.5 mm lower or higher at the center than the two ends) that’s within the ultimate accuracy goal of the machine.