Servo Limitations

[nashyboy]

Hi everybody,
I am new to CNC machine building and was wondering if anyone can shed some light on controller limitations before I decide on a final system. I would like to know a couple of things...

1) Is there a controller available which will allow me to manually jog or control the servos without programming them (a bit like the manual controls on a commercially available CNC lathe - for example)? So I can choose the axis I want to move and fine tune it through manual jogging or even perhaps manually machine a piece if required. (I have seen a "joystick" controller, but i'd much prefer a "dial" which hopefully can be adjusted for slow and rapid feed).

2) can two steppers be controlled through one channel? Eg. If I want to have two servos controlling one axis? Are there any limitations (Accuracy / torque) on this type of system?

Thanks for taking the time to read this, hopefully someone can help me out!

[mcpltd]

Originally Posted by nashyboy Hi everybody, I am new to CNC machine building and was wondering if anyone can shed some light on controller limitations before I decide on a final system. I would like to know a couple of things... 1) Is there a controller available which will allow me to manually jog or control the servos without programming them (a bit like the manual controls on a commercially available CNC lathe - for example)? So I can choose the axis I want to move and fine tune it through manual jogging or even perhaps manually machine a piece if required. (I have seen a "joystick" controller, but i'd much prefer a "dial" which hopefully can be adjusted for slow and rapid feed). 2) can two steppers be controlled through one channel? Eg. If I want to have two servos controlling one axis? Are there any limitations (Accuracy / torque) on this type of system? Thanks for taking the time to read this, hopefully someone can help me out!

Most servo drivers are bumb (need external control) and to have a jog feature, i think you will need to look at one with some controller or positioner built in, and that will require some programing, but not a lot.

Regarding having two steppers or servos, are you talking about a follower application where one axis follwer the other?
If so that is not a problem with most drivers with onboard control.

[nashyboy]

The programming you have said would be required...would this be programming within cnc software or via an external microcontroller?

The servo setup I am considering would work best with one motor following the other's position in the same axis, so I am glad you have said this is possible.

[mcpltd]

OK, what you are looking for is a product like this:
http://www.motioncontrolproducts.com.../Harminica.jpg
This is a 1200W digital servo amplifier with onboard motion controller.
It is fully programmable and can do 1.5 Axis of control (Follower or Ecam)
the datasheet is here http://www.motioncontrolproducts.com.../Harminica.pdf

If you are looking for a stepper solution, the Microlynx would work very well
http://www.motioncontrolproducts.com/c2/uploads/mx.pdf

You will need a dumb driver for the second axis, and the main axis will be giving the second clock and direction.

With the Microlynxs you will need a high speed differential I/o card to but with the harmonica you will need the advanced version.

Originally Posted by nashyboy The programming you have said would be required...would this be programming within cnc software or via an external microcontroller? The servo setup I am considering would work best with one motor following the other's position in the same axis, so I am glad you have said this is possible.

[nashyboy]

thanks...you've given me somewhere to start!