extreme axis limit

[bghowland]

I have a bridgeport 412 and just replaced the z axis moter ,now get a extrem axis limit failure code can anyone help me?

thank you
brian

[machintek]

You did not say if this has a Heidenhain or Fanuc control. The machine came with both.
You have to understand the process of homing. The machine sees the home switch, and then looks for a marker pulse that occurs once per revolution of the motor, then it counts so far and stops.
I would change the relationship of the motor pulley to the ballscrew by 180 degrees. In other words loosen the belt and turn only the motor 180 degrees and put the belt back on. This should get you past that issue.
But if you have a Fanuc control, it always knows how far it was to that switch. If that value changes, it will give you a overtravel alarm. Boot the control with P, Q, and CANCEL held in. Then release those keys and home it. This tells the control to ignore the stored value and write a new one.
REMEMBER that you will have to reset your tool change height parameter!!
Or else your tool changer will crash. See your maintenance manual for which parameter that is in whatever control you have.

George

[bghowland]

I have a Heidenhain controler, tryed turning moter 180 degrees an it still reads extreeme axis limit .could the card on te new moter be bad or the switch need to be adjusted?
brian

[machintek]

Is it on the extreme limit switch?
Can you press and hold the yellow push button switch to keep the drives on and jog it off the limit? There is a brake on the Z axis so I do not advise pulling it off to lower the head.
How did it get onto the limit? If the axis moved, then I would believe the motor and drive are good.
You probably have BORCH drives. Good luck getting them fixed!

George

[bghowland]

yes. it is on the extreme switch but i can move it off by turning the belt .
i do have borch drives but they look good, could the encode on the back of the z moter be bad how can i tell?
brian

[machintek]

The easiest way to tell is to move the Z axis down, start the home position, press and hold the Z home switch, it should stop in .5 inches or less. If it does not then you may have a problem with the encoder. Please make sure you move the Z axis down far enough to do this safetly.
Have you tried holding the yellow drive enable button in, and trying to handwheel the Z down off the switch?

George