Need Help!- Fanuc 18-T Setting Grid Shift

[Chuckwagon]

Hello all,
I have a Hardinge T42SP (Fanuc 18-T control) with a 12 station Top Plate which I replaced the turret clamp and turret reference switches. I now need to perform a turret home and grid shift setting. Can anyone help with a procedure for setting grid shift amount or for setting turret home position?
Thanks.

[Al_The_Man]

What servo axis is the turret driven by?
I am not familiar with that machine but I could probably tell you the grid shift for a particular axis.
Are you sure it is axis driven?
Al.

[Chuckwagon]

The controling axis of the turret is 'A'. The turret homes off-center of lock down position. I can move the turret manually back to lock down position and zero out the encoder register, but when I perform a zero return, it returns to the original off-center position.
Chuckwagon

[Al_The_Man]

The grid shift parameters are shown stored at P1850.
I take it you do not have the parameter manual or maintenance manual?
Is it 18TC or 18TB?
Al.

[Chuckwagon]

Yes we have the manual but have not been this deep in the controller ourself. The fanuc is a 18B model. I've been changing the grid shift # trying to home in lockdown position. Getting closer but not there. When the cam crosses the prox it deccels and goes too far past prox sw for home position. What and how needs calculated with abs encoder # and grid shift # to get correct position after cam detection.

[Al_The_Man]

The grid shift is in encoder counts/resolution, remember you can go in the minus as well as plus.
You may have to move the home switch if the grid shift does not take it far enough.
Al.

[Chuckwagon]

Is there a formula to calculate the encoder units/ 'Number' which will be put in the grid shift to move to home position? We know where we start (the numbers in diagnostics 301 & 302) and we know where we want to be (zero position numbers in 301 & 302) but can't calculate the number to make it so.
Chuckwagon

[Al_The_Man]

Encoder counts x4 is the resolution of 1 revolution of the motor.
The final resolution is then calculated from the number of motor revolutions per inches or degrees of movement.
Al.