hobby cnc question

[chrispare]

not sure if is in the right spot but here goes.

I have a hobbycnc driver and steppers,
my question is what is the difference between 1/2 ,1/4, stepping??

thanks

chrisp

[WayneHill]

Chrisp,

A stepper motor with 1.8 degrees per step will take 200 full steps for one revolution.

1/2 step will take 400 steps for one revolution. 1/4 step will take 800 steps for one revolution.

[jalessi]

Chris,

The precision of a stepper motor is determined primarily by the number of steps per revolution; the more steps, the greater the precision. For even higher precision, some step motor drivers divide normal steps into half-steps, quarter steps, eighth steps, or even smaller divisions of micro-steps.



FULL-STEP

In full step operation, the motor steps through the normal step angle e.g. 200 step/revolution motors take 1.8 steps while in half step operation, 0.9 steps are taken. There are two kinds of full-step modes. Single phase full-step excitation is where the motor is operated with only one phase energized at-a-time. This mode should only be used where torque and speed performance are not important, e.g. where the motor is operated at a fixed speed and load conditions are well defined. Problems with resonance can preclude operation at some speeds. This mode requires the least amount of power from the drive power supply of any of the excitation modes. Dual phase full-step excitation is where the motor is operated with two phases energized at-a-time. This mode provides good torque and speed performance with a minimum of resonance problems. Dual excitation, provides about 30 to 40 percent more torque than single excitation, but does require twice the power from the drive power supply.


HALF-STEP
Half-step excitation is alternate single and dual phase operation resulting in steps one half the normal step size. This mode provides twice the resolution. While the motor torque output varies on alternate steps, this is more than offset by the need to step through only half the angle. This mode has become the predominately used mode by Anaheim Automation because it offers almost complete freedom from resonance problems. Motors can be operated over a wide range of speeds and used to drive almost any load commonly encountered.

MICRO-STEP
In the micro-step mode, a motor's natural step angle can be divided into much smaller angles. For example, a standard 1.8 degree motor has 200 steps/revolution. If the motor is micro-stepped with a 'divide-by-10', then each micro-step would move the motor 0.18 degrees and there would be 2,000 steps/revolution. Typically, micro-step modes range from divide-by-10 to divide-by-256 (51,200 steps/rev for a 1.8 degree motor). The micro-steps are produced by proportioning the current in the two windings according to sine and cosine functions. This mode is only used where smoother motion or more resolution is required.

Jeff...