I have just googled this VFD and come up with this link to a forum. There is a chap on there who seems to know quite a lot about it.The link is at
http://www.cnczone.com/forums/archive/index.php/t-24107.html.
The connections to your VFD bear no comparrison to those on a modern VFD
We now appear to have, as standard 6 pins.
1. M3 connection 2. M4 connection 3. 0v M3/M4 4.V+ connection 5. Speed voltage reference 6. 0v speed regulator
Pins 1 and 2 connected to ground (via a relay) give forward or reverse drive - both cannot be "on" together
Pins 4.5 and 6. which are electrically seperate from 1,2 and 3 give a +v and 0v reference to attach to a potentiometer and pin 5 is the return from the pot wiper, which sets the speed.
The connections shown for the Oracle VFD are nothing like that. You require momentary contacts on the forward or reverse pins (not on/off switches) and the speed sensing seems to be somehow all intertwined with it .
Unless you are a competant electrical guy, I would suggest, in all honesty,that you get yourself a more modern VFD that has standard connections. On the standard set up, Mach 3 has the relevant outputs - M3, M4 and PWM (to run a digispeed controller to control your VFD) - and THEY WORK.
I have had M3 and M4 going for some time, but I also fitted a Digispeed two weeks ago, and now I can control the spindle speed to 1 r.p.m from the computer. It is marvellous.
Without being a pessimist, I think you will spend a lot of time with your old Orac, and all you will manage is to get forward and reverse going satisfactorily - and that will still leave the speed control up in the air.
Anyway - have a look at the link and see what you think