3D CAM, servo or stepper ?

[skenn_ie]

Hi. Having just bought a 3D measurement machine with a working volume of about 1m^3, for conversion for additive and conventional machining, I would appreciate some advice. The machine currently has 3 servo-motors with tachs and position strips. I intend to use an Arduino to control position, but should I replace the servo motors with steppers, or stick with the servos ? The machine came with a minor accessory, superfluous to my requirements, a Renishaw PH10M and TP20 std force probe.

 

[Harald Kapp]

Servo + position sensor should be good. The advantage is that you always know the exact position thanks to the position strips. You don't have to worry about finding the origin after power up or about missing steps.
The "disadvantage" is that you'll have to evaluate the sensor data from the position strips.

 

[KMoffett]

Unless the strip is an "absolute" position encoder, you still have to relocate the origin on power-up.

 

[Harald Kapp]

Of course, you're right. I implicitly assumed the encoder to be of the absolute type. I inferred from the "position strips" - incremental strips do not give an absolute position.

 

[skenn_ie]

Absolute of incremental, I don't yet know, but even incremental will avoid missed steps (of steppers) under load.