Thanks for the complete specs in your report - very helpful.

Actually these hockey-stick shaped lines are very normal behaviour - each motor accelerates, at the same rate from "stopped", and both motors reach the same top speed at the same time, so the line that comes out is the product of these two, synchronised movements. This line is straight-ish, but it's not actually pointing at the target, it's far off to one side.

So each motor has a different target: MotorA is moving 1000 steps, MotorB is moving 1500 steps, so MotorA starts slowing down long before MotorB does, and as MotorA slows down, it pulls the line to one side, actually putting it back on track to hit the target.

The "move to point" function is exactly that and no more, it moves the pen to a particular point, but makes no guarantees about the path the pen would take, and in actual fact, the simplest way to do this his happens to move the pen in an indirect fashion.

To plot a straight path, use "move direct". Good luck!

sn