Z axis threaded rod question

Hello all

I'm just ordering parts to build a new 3d printer on my current printer prusa i3 Aluminium frame the Z axis uses a M5 threaded rod and nut, I was thingking of using a M8 or M10 Leadscrew and brass nut, the thread pitch on those will be 1.5 / 2mm which is greater than the m5 thread pitch on my current z axis.

so I assume my Z axis speed could be quicker (less rotations per mm) I think I will choose the 2mm pitch option should I change my stepper motor from a 1.8 deg to a 0.9 deg stepper thus keeping my original settings in my firmware or stick with the 1.8 and have a quicker z axis ?

You are fine with the steppers you currently have. I went from a m5 threaded rod to a 4mm pitch lead screw with no noticable change in print quality. You will need to change the steps per mm for that axis in the firmware however. A good calculator to figure out the proper setting is here: http://prusaprinters.org/calculator/

According to the calculator, you would want to change your steps to 1600. I wouldnt suggest a .9 stepper for the z axis.

thanks for the reply I went for a 8mm Lead screw with a 2mm pitch.

I'm still building the printer I have the frame and motors fitted I haven't tried them out yet, but they do move much smoother than the m5 threaded rod so it should be a good improvement.