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Author Topic: Linear Scales  (Read 3915 times)

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Linear Scales
« on: February 26, 2013, 05:36:49 PM »
I use to have a knee mill that I setup with AC servos on it and it was running under Mach 3, so I have some Mach 3 experience but no experience with linear scales and Mach 3. I am now looking at getting a knee mill with steppers and I have a question about using linear scales with Mach 3. Will linear scales allow me to turn the steppers off and use Mach 3 as a DRO under manual operation? Also can the linear scales be used for positioning when using the steppers and Mach 3 as a CNC?
Re: Linear Scales
« Reply #1 on: February 26, 2013, 08:59:54 PM »
Mach3 is strictly an open-loop controller.  You can use the scales as DROs.  Mach3 will NOT control the machine based on the scales.  You can get that capability with some third-party hardware motion controllers, like KFlop, but Mach3 will be totally unaware of it.

Ray L.
Ray L.
Re: Linear Scales
« Reply #2 on: February 26, 2013, 11:10:46 PM »

Thank you for the reply. I am primarily interested in using the scales as DROs but if I can get hardware that will also allow it to run the steppers in closed loop that would be advantageous.

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Re: Linear Scales
« Reply #3 on: February 27, 2013, 03:42:36 AM »
In my opinion trying to close the loop is a waste of time with steppers however updating position from encoders after manual movement should be possible without any hardware.
I was interested in doing something similar a while back, instead of linear scales I was wanting to use my servo drives encoder outputs. Problem with that was I could not get the hardware I was using at the time to accurately read the high counts from multiple encoders. As you will be using much lower counts from the linear scales you likely wont have that problem even if being input via the parallel port.
Anyway what I had was some VB which, when I pressed the Reset button, looked at Machs position and encoder position and it would then pop a message up if they were different. It would tell me what the differences were and ask if I wished to update Machs DROs to encoder position.