[meknik2001]

Hello

Basically, I need to know what kind of coupling are normally used to stepper motor axis.

By the way... somebody knows how big can stepper motor axis be?

[jhudler]

When you say axis, are your refering to the shaft size?
What do you mean by; big? Size of the motor or the size of the shaft.

[meknik2001]

Yes, you´re right.
I´m asking about stepper motor shaft. (When I posted, I didn´t know how to say "eje")

Well... I´m thinking about design a Small CNC and my principal shaft (screw endless) has 30mm diameter.

sorry for my English

[jhudler]

Your English is fine.

To couple a stepper motor shaft to a lead screw, you use what is called a "Helical Beam Shaft Couplings" or something similar (with Zero Backlash).
For example see: http://www.mcmaster.com/nav/enter.asp?pagenum=1147
You do not want to use a rigid coupling. This would place unwanted stress on the motor from even the slightest misalignment.
Size the coupler for the shaft sizes and the motor torque.

[hignog]

This is what i use.

http://www.slidesandballscrews.com/f...ngs-p-141.html

Hello

Basically, I need to know what kind of coupling are normally used to stepper motor axis.

By the way... somebody knows how big can stepper motor axis be?