THE STORY OF A BUILDER

I used all of the original drives and motors on the VMC.
The axis drives are a triple-stack fanuc unit (all 3 axis drivers on a single pcb set),
the spindle drive is a fanuc unit which drives a rather large 15hp fanuc servo motor.
All motors are brushless ac servos.
Interfacing to the drives was really quite easy since I had the original wiring diagram
for the mill and most of the connections were obvious.
Each of the axis drives take a +/-10v analog signal for velocity control and a simple digital line for enable.
I used a mesa 5i20 board with 1 x 7i33 (4 axis servo card) and 2 x 7i37 (opto-isolated IO cards).
The axis velocity signals come straight from the 7i33 and the motor encoder feedback
(8000cpr) goes back into the 7i33.
The enables are triggered from 3 io lines on one of the 7i37 cards.
The spindle drive is similar except it takes a 0-10v signal for the velocity
and 1 of 2 contacts must be closed to request either fwd or rev motion.
I used the 4th channel on the 7i33 for this and fed the spindle encoder feedback
back into the 7i33 to provide speed feedback for rigid tapping, etc.
Most of the rest of the IO is used to control the automatic tool changer which
was by far the longest part of the retrofit.
Infact it's still in progress but should be complete within the next week or so.
The rest of the mill has been finished for some time now and I've been using it in anger for a while.
I'm very very pleased with the retrofit and in the process have learnt a lot about EMC, HAL and ladder logic.
I ripped out the original siemens acramatic control from the rear (control) cabinet
and it now houses the mesa cards (on din rails), an old p3-500 and lots of fresh air.
Next time I have the camera in the shop I'll take some photos.
Once the automatic tool change is working I plan on posting some video.
I should add that I retained all of the original relay driven safety circuits and am very glad I did so.
When this thing moves it's scary and with 1kW ac servo motors on the x and y
axis it's not going to stop in a hurry.