Z return margin error

[Shotout]

Searched through the archives and couldn't find this one. When I power up in the mornings I hit the power up restart button on our Tool Room mill. The spindle moves to the extreme of Z+ and begins moving towards home. As it approaches home I alarm out with the code Z Return Marg. I hit reset and power up restart again and usually it homes the Z and then the table, cycles to tool one and all is good, no lost of indexing from the previous day etc. Before shut down I always perform a tool change to an empty pocket and then I hand jog Z +2.0 (approx) past home. I varied this to Z- as well as leaving it homed. Same results. Can anyone tell me how to clean the sensor assuming that is what the problem is. My machines use grease fittings rather than a cyclic oil pump for lube and I'm wondering if to much grease could cause this. Any help would be appreciated. Thanks

[gar]

0610156-0655 EST USA

Shotout:

In your HAAS manual there is a section on ALARMS.

Checking a mill manual under X zero return margin too small. This is an error that occurs when the returned limit switch position is incorrect relative to the once per revolution mark on the lead screw. We have never had this error on any of our machines except when readjusting after having changed a cable.

Probably only requires a slight reposition of limit switch, or if the limit switch is a prox switch, then maybe there is contamination, a small metal chip, that causes an erroneous signal from the prox switch,

.

[Geof]

Originally Posted by Shotout ...Can anyone tell me how to clean the sensor...

Take a cotton swab and just wipe the end of it clean.

But perhaps you mean where do you find the sensor? I have MiniMills not Toolroom but they are the same, or very similar, Z assembly. I think the sensor is at the top of the Z guides; cylindrical thing about 5/8" dia. and 3" long with wire coming out one end and flat on the other. There is a little metal plate that passes the flat when the axis moves and your dirt may be on either.

[Shotout]

Thanks. I'll check it monday, we have been slammed all week so I never got a chance to check the fine manual yet.