Hi all,
I am now nearing the completion of my bridgeport retrofit project however there are just a few irritating glitches remaining which prevent me from using the machine properly.
I think I have narrowed the fault down to interference from the VFD which actually seems to be getting into the computer and making it unstable.
If I run a g-code program I can runn the machine at full speed (5 metres per minute) and I get a fast smooth response and everything appears to work just nicely. This is without the spindle running.
Anything up to about 50% of my max spindle speed and it still runs nicely but as soon as I run the spindle much above 50% the machine starts to respond in an unusual way.
This can take a number of forms:
1. When doing rapid movments the table will judder whilst trying to reach its target location
2. The spindle will ramp up to full speed and then ramp down a bit and then ramp up again.
3. When the spindle gets close to full speed mach 3 will go into e-stop mode stating a driver watchdog error as the cause.
My setup is as follows:
I have a Huanyang 4hp VFD in the rear cabinet of the machine and it is mounted in the top left corner. The output wires are not shielded but all three phases are twisted together and there is only a short (6 inch) exposed area before they go into earthed metal conduit up to the motor. There is an airgap of at least 1ft between the output wires and the pc or any other circuit. The single phase supply wires are unshielded and do run alongside a lot of other wires however it is my current understanding that the input side should be 'clean' and only the output side is noisy. The control cables (forward, reverse and speed are shielded; earthed at the VFD end. The direction wires are connected though cnc4pc solid state relays which then goes to a cnc4pc breakout board. The speed control (0-10v) wires go to a cnc4pc variable speed board which then goes to the cnc4pc parallel port breakout board.
In my opinion the faults seem to suggest noise from the VFD is actually getting into the pc and causing it to output some strange stuff. This would explain the driver watchdog errors, the juddering axes and ramping up and down of the spindle speed.
Anyyway ... basically I'm really stuck with this. I need to solve this problem as I cant use my machine properly in this state but I don't have a clue what to do next. I would be really greatful if somone could help me out here.
Regards,
Dom