Nema 23 4Nm Stepper Motor

**Jonathan** · 06-02-2013

Originally Posted by Tenson

Sorry to keep this off topic from the sale, but what is the difference between a servo motor and this? Servo really just means a feedback loop which is what the optical encoder provides. Also is the smoothness Jazz mentioned not simply to do with the motor? I wouldn't think the encoder will be responsible for that.

The term 'servo motor' is generally used for DC or brushless DC motors, which tend to have a low pole count compared to a stepper motor, so they are quite different in that respect, however the control systems are similar. The 'smoothness' is greatly dependent on the resolution of the encoder, which is where 'genuine' servo motors are likely to be better since good ones come with much higher resolution encoders - 16-bit and 20-bit are common, compared to only 10-bit (1000ppr) on the stepper motor linked to. To put it simply, with a higher resolution encoder the controller is getting more information about the motor, so is able to compensate for errors, and smaller positional errors.

**Gary** · 06-02-2013

The encoder is 1000 line, this is 4000 PPR.
Typical ac servo motors have at least 2500 line encoders and that is 10000 PPR.
While there are incremental encoders with a higher resolution than 2500 line, they are not normally found in the back of an AC servo motors, and if a higher resolution is needed, then you would use a Sine / cosine encoder.
DC brushless servos are normally on the smaller size. (up to about 200W)
DC servo are normally brushed and are a thing of the past, but are still used on some applications.

Originally Posted by Jonathan

The term 'servo motor' is generally used for DC or brushless DC motors, which tend to have a low pole count compared to a stepper motor, so they are quite different in that respect, however the control systems are similar. The 'smoothness' is greatly dependent on the resolution of the encoder, which is where 'genuine' servo motors are likely to be better since good ones come with much higher resolution encoders - 16-bit and 20-bit are common, compared to only 10-bit (1000ppr) on the stepper motor linked to. To put it simply, with a higher resolution encoder the controller is getting more information about the motor, so is able to compensate for errors, and smaller positional errors.