[meputtin]

I've got a hardinge chnc III that we pulled the x axis motor and encoder off of, and con not establish the x axis reference.When we put it back together it over travels on x when we try to home out.Any help would be greatly appreciated. Thanks Dave

[WGoyer]

Dave,
Hardinge took something that was hard already and made it VERY hard. The procedure varies by CNC type:

Fanuc 0TB, Fanuc 0TC, Fanuc 18T, maybe even Fanuc 10T?

If you can locate the Hardinge book, it is buried in there. If you can't find it, I'll try to get it for you at the office Monday.

Warren
www.uptimecorp.com

[meputtin]

The controler is an 18 T. Been looking all day ,and pulling hair out.Almost bald now

[WGoyer]

Dave,

I'm going to guess that they didn't put external encoders on the ends of the screw on this model. If there is an external encoder in addition to the one inside the red cap motor, disregard the following. We'll have to wait until I can look it up for you Monday.

Generally, the idea in zeroing an 18T, is to rapid up to the decel cam, slow down, fall off the decel cam, watch for the next marker pulse and stop. Some things have to happen first however: the axis must be up to zeroing speed (defined as 128 counts of servo lag) before it sees the marker the first time, and it must have seen a marker before it sees the decel switch (remember it sees one every time the motor turns). If the motor is oriented wrong, it might overtravel before it finds the first marker after falling off the switch.

On a Hardinge, the brute force fix for this might just be to loosen the motor, turn the motor shaft a little and try again. Not too scientific, but effective.

After a true zero return, the control looks at the grid sync parameter (if it is non zero) and jumps to an exact point. This is useful on a Hardinge to get the exact distance from centerline that they advise.

Good luck,

Warren
www.uptimecorp.com

[mikkie]

if it is just a software overtravel i.e.. does not go into full emergency then just hold cancel P on power up to bypass your software over travels then home it, power down and back up normal and all should be good.

tom