Printrbot Z Axis 5mm threaded rod upgrade

I was unhappy with the 5/16 threaded rod that the Printrbot comes with and the Z-ribbing artifacts. The problem is the stepper motors have an uneven amount of steps with the 5/16 rod. When you print something with the 5/16 rod, your layer heights will be off every x number of layers unless you choose very specific layer heights. By going to 5mm threaded rod(mine cost $15 shipped from McMastercarr) you can change your steps from 2267.72 to an even 4000 steps. This gives a nice even layer heigh