How to program tool change on large cnc lathe

[cuttergrinder]

I started out running a mazak cnc lathe with mazatrol control so tool changes were handled by mazatrol. Now we have a large Leadwell cnc lathe with fanuc control. It will turn about 30" x about 13' I know on most smaller cnc lathes they send them home using G28 or G53. Most parts we do are not nearly as long as this lathe so I change tools with the carriage up closer to the part. I usually use this line in my programs to position for a tool change.

G54 X25. Z8. T00

Most parts are no larger in dia than this and my boring bar is a little less than 8" long so this usually works well but I know at some point others will be running this machine and would like to know what the normal way of positioning the turret is for a tool change?

 

[sinha]

The normal way is to change the tool at the home position.
Z homing may not be necessary. In such a case, pull the turret to a clear Z position and command G28 U0, before tool change.
If Z homing is also required, command G28 U0 followed by G28 W0, before tool change.
I consider it safer than G28 U0 W0 which shows dogleg effect (tailstock may interfere).

 

[alphonso]

We use:
G28 U0
G0 ZXXXX (somewhere that clears work, tailstock)
TXXXX

 

[cuttergrinder]

Thanks guys. Actually just sending it home in X would work most of the time since this lathe is so big. I will start using G28 U0. I have been changing tools at X25. Z8. X home would be a little safer if I was running a big job. I just never wanted to send it all the way home in the Z to make a tool change since it is so long and it has pretty slow rapids so if I did a tool change would take forever.

 

[DouglasJRizzo]

On really LARGE lathes, I had taught customers to set a G30 2nd home position somewhere in the middle, or just short of, for tool changes.
On most Fanuc CNCs it's Parameter 1241, and normally set in mm's. So you would give it a G30W0 and the turret would go to the 2nd home rather than all the way back.
You could even give it a G30u0 and have the X somewhere closer to the part.