Our 10hp 7500 rpm spindle on a 1996 Fadal 15XT(30x16 table) began to drop RPM's at various intervals. For example... while running 600 rpm, it would go from a load of approximately 30% up to approximately 90% and drop down to about 300-400 rpm. Seconds later it would recover and run fine for awhile. Service tech eliminated the possibilty of a bad encoder by swapping it for a new one, and the same problem persisted. This problem occurs at all speed ranges from low rpm up to 7500. Service tech suggested an all new Baldor Vector Drive. We had ours rebuilt, but now the spindle motor wants to spin backward, at 150% motor load, and only turning at 30 to 40 rpm in reverse with a S500M3 command. S500M4 command will make the motor want to try and spin clock-wise, but with the same 150% load. C axis fault Motor Overload occurs when I stop the motor from the STOP button on the Vector Drive. I do not know what the problem could be... bad Regen Resistor used for braking? Encoder now bad? I did run through the program function on the Vector Drive and zero balanced it to the machine. We even swapped out controller cards that went to software version FA7; the original card was software version FA5. If anyone has suggetions, please help!

just cuious... have you checked out the motor? sounds like the bearings are going south or you may have bad connections to it ...just a thought

If the motor is 3 phase swapping any two wires will reverse the motor. Since it ran better before you "fixed" the drive, I would start there. Call the guys who rebuilt it. I would hope they would stand behind it and also have some suggestions.

Eric

This was an easy fix with the new encoder style. It didn't solve my spindle motor problem though.

I am not familiar with the Fadal 8030, but basically there are two types of encoder mounting, one is the through-hole type where the encoder disk is mounted to the actual motor shaft directly, these are usually the most awkward to remove due do the disk seizing onto the shaft over time. The second type is the separate mount type that has a flexible coupling between encoder and motor shaft. Either way it is usually necessary to remove the encoder before the motor end plate. There is often an access hole to get to any set screw.
Hopefully someone who has done it on a Fadal may answer.
Al.