[reabdet21]

I had just finished adjusting the spindle speed to 2600 when a few seconds later my spindle shut off and the screen indicated the emergency stop had been activated. It will not clear.

I do not have a manual so I am limited in my research. What features on the mill will activated the emergency stop? What would be my best avenue for trouble shooting? Thanks, Jim

[machintek]

You need a schematic to check for voltage along that "string".
You can start by checking for voltage at the emergency stop switch. That it goes in and comes out with respect to ground.
You did not state what year/version your machine is. There are many with a lot of internal changes.

George

[reabdet21]

I found the breaker tripped for the motor. I pushed the reset and it clicked closed.

Fired it up. It ran for about 5 seconds making a rattling noise and then something popped. The noise slowly died down and left the spindle rotating quiet and smooth. I shut the spindle off and then attempted to restart the spindle. The motor just hummed like the brake was on. I immediately shut it off and it is now parked.

Just a guess but something has happened to the motor/drive pulley. The spindle is not frozen.

Any suggestions as to the problem? What would the loud pop have been?
Anyone know where I can get the instructions on motor removal for the variable speed?

Needless to say, I think I have some major repairs awaiting. Has anyone experienced this before? Jim

[reabdet21]

After musing upon this a bit more this evening, since this all occurred after I had adjusted the speed, could the spring loaded pulley have stuck and the "pop" was the pulley snapping back closed?

The motor was overloading to trip the breaker so the draw could have been pretty high on my static converter. My guess this evening is that I also lost a phase from the converter as a result of attempting to get the mill running. That would result in the hum because I did remove the "D" plate below the motor and the pulley easily rotates. The motor is not frozen.

What is the method of lubrication for the variable pulley on the shaft?

I am considering switching to a VFD and provide a 115V AC supply directly to the leads disconnected from the 115 AC output transformer. Would this be the best solution for using a VFD?

[John Bennett]

A (Bridgeport) CNC does not like static convertors but rotary and VFD are the prefered choices. Check to see if all phases are working, the spindle motor is the only part of the mill that requires three phase, the rest of the components can be supplied 220 volts single phase an have the transformers reduce the voltage as required (wiring diagram would help show this) .

[machintek]

I use a static phase converter at home just to fire up a head to make sure it is working correctly after I rebuild it. BUT, any drag and it will cut in and out and I have blown them up. The artificial leg is created for only a few seconds. The motor HP is about 10% of what it is with 3 phase power. Because the static device is so unbalanced you will always trip the overload.
The head should not rattle. And maybe you broke the vari drive belt. Remove the plate on the bottom of the belt housing beneath the motor. Turn the spindle by hand and see if the motor shaft is turning. Or look through the air port above the speed changer dial and see if the belt is turning while turning the spindle.

George

[reabdet21]

Thanks guys, I really appreciate the help.

I did open the static converter this morning and found the cap melted. Everything else in the converter looks ok. I have another cap and I think it will fix the converter and restore the missing phase causing the motor to hum.

That said, it still does not fix the original problem. When I had it running the last time, there was a very loud snap or pop and then the belt dimished vibration in about 2 seconds back to very smooth running. Since it was running smooth and quiet, that really sounds like the pulley stuck in an open position and finally slammed closed as I was adjusting the speed control again.

Does anyone know how I could lube the shaft where the pulley slides without opening the head?

My next question is a VFD for the machine. That is the way I want to go. I see the machine is fused for 10 amps and the 3hp vfds are rated at 10 amps. Would that be the proper size for my 2hp Ez trak?

A third question. When using a VFD, should I power the computer and servos with another 115volt supply. I could easily do that. What I worry about is the frequency shift when using the speed control on the VFD. How will that affect the computer?

If the VFD is used to power the entire mill, is there any preference for which phase would power the computer?

Thanks, Jim