Quote Originally Posted by tribbles View Post
What sort of speed are you after? You'd need to go pretty thick for that length if it's going to be fast and not whip (25mm at least).

I'm running 1500mm lengths of 25x25, giving me about 18m/min, and with 400 steps per revolution, accuracy is 0.0625mm. But I've also got some pretty hefty steppers to drive them though...
Well, im set on going with servo motors all round, 2 on the X ( each screw ) 1 for Y and smaller 1 for Z. im going to use 20x5mm screw for my Z but i am unsure if i will get the accuracy with the X and Y if i use 25x25 for the X and 20x20 for the Y
i was thinking of using a belt reduction connecting the servos in the regions of 3:1 or perhaps abit higher, What are your thought as servos are fast but need gearing to get torque. As Tribbles said about his accuracy being 0.0625mm could i achieve anything better with servos in conjunction with the pitch of screw.

Or would it not matter if i went for a finer pitch screw and kept with the servos and still be able to achieve good rapids relying on the high speed of the servos!

AHHHHH questions questions questioins :(