[PBr]

Hi,

I got a problem with my Z axis on my mori mill with fanuc 10M controller. Ocassionally when i program a move in Z direction with G0 in MDI, then the Z axis starts to move at full speed (does not care about rapid feed override switch, really very fast) in either direction until an EXCESS MOVE alarm is raised. The alarm is raised after some travel, once it was few cm's, next time cca 25cm. This seems to be very dangerous, until now seems i got lucky enough the spindle moved upwards.
There is one more thing worth to mention - last two times it happened after i ran a long program via rs232 (ran ok, then i wanted to move the spindle to a certain position), the last command was G28G0Z0, which i used to interrupt in half way with the reset button.

Any suggestions?
thanks in advance

[Al_The_Man]

It sounds like an axis run-away condition, are these DC motors with tachs?
Al.

[neilw20]

Or is it in relative mode, and z5 gives an instant incremental Z move upwards?

[underthetire]

You must use a g91g28z0, otherwise the z will dive to part zero first. Also make sure your not in inches per revolution mode.

[PBr]

The motors are DC's with encoders.
Also it did not matter whether the machine was in G91 or G90...i'm pretty sure this is not the intended behavior. If it was correct, then it would move with the standard rapid speed (set to 3000 mm/min).

For me it seems to be a bug in the controller or HW error - also it happens only on the Z axis.

[underthetire]

Wow, almost never saw yellow cap motors on a mori with a 10! You have a tach failing in the motor.

[Al_The_Man]

Soon after the introduction of the 10 was about the time Fanuc transitioned over to Red Cap AC servo's.
At this time there were some of the DC servo's fitted with resolvers in place of encoders and tachs.
These were driven off of a small gear on the rear shaft.
Al.