Fanuc M 0 controller - Issues homing and Y overtravel

Kjeksen · Nov 6, 2018

Hi there.

We have some issues with our CNC machine with Fanuc M O controller.

It started with a stuck switch below the table on the machine. We got the switch unstuck and testet
the switch for function. But then the table was not near end travel on Y axis. Now the machine remembers this position and we cannot move the Y axis to home position before the end of travel alarm comes on.

I reckon I must in the paramteres to change some input to get the table back to its max travel?

VTM · Nov 6, 2018

Try this. Power down machine. Power back on holding down the P and CAN keys at the same time. See if you can home the machine now.

Kjeksen · Nov 6, 2018

VTM said:
Try this. Power down machine. Power back on holding down the P and CAN keys at the same time. See if you can home the machine now.

Sure. Will try that tonight

Kjeksen · Nov 6, 2018

Did not work... Y travel max is still "stored" about half of the travel available on the machine.. I thinking there is some parameters that needs changed?

VTM · Nov 6, 2018

Well, have a read through this.
https://www.practicalmachinist.com/vb/cnc-machining/fanuc-0m-re-setting-zero-return-216152/
Maybe it will help you out. Was the machine running fine before and the stuck switch caused this? If so p+cancel on boot up should have worked.

Kjeksen · Nov 6, 2018

VTM said:
Well, have a read through this.
https://www.practicalmachinist.com/vb/cnc-machining/fanuc-0m-re-setting-zero-return-216152/
Maybe it will help you out. Was the machine running fine before and the stuck switch caused this? If so p+cancel on boot up should have worked.

Yep machine was running fine. But when we testet the switch the Y axis was not at end of travel, and seems that the position we had the table in when we testet the switched is stored. Now the machine gives Y overtravel at the exact same spot and we cannot move the table beyond that position. That is why my theory is
that something has been stored in a parameter somewhere that makes the machine believe that it is at end. Like a soft stop.

Vancbiker · Nov 6, 2018

The Y soft limit parameters are 701 for the positive direction and 705 for the negative direction. Assuming you are getting alarms 520 or 521 when you try to move Y, you can set 99999999 to 701 and -99999999 to 705 and that should essentially cancel the soft limits and allow you to reference home the axis. Once you successfully home the axis, return the parameters to their factory settings.

landslide · Nov 7, 2018

sounds like the reference point return needs to be reset.

zero the axis bit then perform a reference point return and the switch will automaticaly set it.

Kjeksen · Nov 7, 2018

Vancbiker said:
The Y soft limit parameters are 701 for the positive direction and 705 for the negative direction. Assuming you are getting alarms 520 or 521 when you try to move Y, you can set 99999999 to 701 and -99999999 to 705 and that should essentially cancel the soft limits and allow you to reference home the axis. Once you successfully home the axis, return the parameters to their factory settings.

I have no idea what the factory settings is because the the number stored in parameter 705 is the position we tested the switch in, not the factory setting. 705 is -46000000 wich is the travel of the table in Y axis according to the MTB data I have.

Ox · Nov 7, 2018

Did you keep the CAN and P buttons held down the entire duration of boot-up time?

------------------------

Think Snow Eh!
Ox

imported_brian_m · Nov 7, 2018

I do not see that you mentioned the machine type. Does it have manual control wheels as well as the servos by any chance? Had a Taiwanese bed mill with this problem because someone had played with the X-axis manual wheel while the power was off.

.

Kjeksen · Nov 8, 2018

Yes. Aslo tried it several times.

Ox said:
Did you keep the CAN and P buttons held down the entire duration of boot-up time?

------------------------

Think Snow Eh!
Ox

Kjeksen · Nov 8, 2018

imported_brian_m said:
I do not see that you mentioned the machine type. Does it have manual control wheels as well as the servos by any chance? Had a Taiwanese bed mill with this problem because someone had played with the X-axis manual wheel while the power was off.

.

Ah sorry bout that. It is a mill. No manual control wheels.

Vancbiker · Nov 8, 2018

Kjeksen said:
I have no idea what the factory settings is because the the number stored in parameter 705 is the position we tested the switch in, not the factory setting. 705 is -46000000 wich is the travel of the table in Y axis according to the MTB data I have.

The above does not make sense.

Did you set 701 to 99999999 and try to move the Y?

Kjeksen · Nov 8, 2018

Vancbiker said:
The above does not make sense.

Did you set 701 to 99999999 and try to move the Y?

Yep. That did work. But the parameter had 3000 stored in it. Wich is not the correct number.
Did not get to see what the right number in this parameter was before it got stored as the wrong one.

Vancbiker · Nov 8, 2018

So, were you able to zero return the axis? Once that is done then you should be able to set 3000 back to 701 and all should work fine. 3000 sets 3mm from the zero return point to the positive soft travel limit.

Kjeksen · Nov 8, 2018

Vancbiker said:
So, were you able to zero return the axis? Once that is done then you should be able to set 3000 back to 701 and all should work fine. 3000 sets 3mm from the zero return point to the positive soft travel limit.

Yep. Got to home Y axis!

Works great now. Set the 701 parameter back to 3000 and works like a charm.

Thanks guys!

mjk · Nov 19, 2018

Just came in this morning and I had a 520 alarm on a NTC vmc w/Omb
As the limit switch appeared a little sticky I figured that was the problem
Machine hasn't run in a couple weeks and the temps are starting to get cold
I tried the usual "p can" with no avail
Ready to start taking things apart I figured a search on here to confirm any thoughts was appropriate and I found the above instructions re rewriting par 701 705 and homeing

After finally remembering how to get into the parameters and following above instructions, I'm back up and running
Many thanks to those above, my Monday won't be so bad after all

Mike

BJinaTJ · Nov 21, 2023

One Kiwa Excel back in business, one more to go.

I'll tell you what.. There isn't anything you guys haven't figured out with these machines. I hope no one gets irritated because I brought an old thread back to life, but you guys deserve a sincere thank you. Drum roll..... After many hours of troubleshooting I'm gonna go home and enjoy a CAN of P's

You're awesome!

DouglasJRizzo · Nov 22, 2023

One other thing to look at would be switch position.
Dad had a Takisawa V1 machining center that would eat Y axis switches every two years. When replacing, I would have to physically adjust the switch to that it would actually fire off when it was supposed to.

Fanuc M 0 controller - Issues homing and Y overtravel

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