Stepper or Servo? Best choice and best source...

[BWay]

I am currently working on my first CNC router. I am planning a 4 axis machine and will be using Nema 23 size motors. A friend strongly recommended servo motors but am wondering if the extra cost is justified? What will gain by using servo's? Also, I have noticed that whether I use steppers or servo's there is many sources and the prices vary greatly. What is a good source that provides good quality at a good price?

Thanks!

[YZF]

Very generally for a similarly sized motor you can run at higher speeds, higher torque and with a higher "stiffness" with a servo motor.

The "price" is somewhat higher complexity and the need to tune the control loop for optimal performance which can be tricky. Traditionally servo systems are more expensive due to the cost of the control electronics, the encoder and the software but this may be changing.

If a stepper motor will meet your requirements and is cheaper it is much simpler to use in a home CNC application.

By the way, it is also possible to run a stepper motor as a servo motor and a 3 phase brushless motor usually used as a servo motor can be stepped in open loop...

Hope this helps...

Originally Posted by BWay I am currently working on my first CNC router. I am planning a 4 axis machine and will be using Nema 23 size motors. A friend strongly recommended servo motors but am wondering if the extra cost is justified? What will gain by using servo's? Also, I have noticed that whether I use steppers or servo's there is many sources and the prices vary greatly. What is a good source that provides good quality at a good price? Thanks!