Quote Originally Posted by Scott Damman View Post
It is more of a delay to start, i.e. the master motor starts moving and the slave starts up just slightly after (which racks the gantry). When it comes to a stop the master stop slightly before the slave bringing it back into square.
Again another obvious suggestion but got to be said to eliminate. Not got loose Pulley.?

Quote Originally Posted by Scott Damman View Post
When you say line filters on the VFD's you are talking input line filters correct?
Yes Input line Filters.

Did you Earth the Frame.?

Re: Separate ground rod then I'd say not because want to use the same ground that mains supply does so don't introduce ground loops. However I'm not expert on this and don't know the differences between American and UK electrics other than frequency.