Zeroturn Fanuc homing fault

Any information regarding the Denford ZeroCentre ZeroTurn ZeroBore Fanuc CNC machines

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g-speed
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Joined: Thu 02 Nov , 2006 17:49 pm

Zeroturn Fanuc homing fault

Post by g-speed » Sun 22 Nov , 2009 17:02 pm

When I try to zero the Z axis on my zeroturn I get a z axis overtravel come up on the screen. The X axis zeros fine. I homed the machine and then set the zero position for the job I was doing. I then needed to change a tool so went to home the machine again (this is the position I use for my tool setter) and it came up with Z axis overtravel? I'm wondering wether I've some how changed the machine datum position???

g-speed
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Joined: Thu 02 Nov , 2006 17:49 pm

Re: Zeroturn Fanuc homing fault

Post by g-speed » Sun 22 Nov , 2009 19:08 pm

I forgot to say I have checked the switch and it appears to work ok. Where there are the two switches and the two blocks to activate the switches, I noticed that the machine goes onto the first double sided ramp where the display reads 0.1???, this is where it stops and says overtravel in Z axis. I'd have thought the first double sided ramp is for homing and the second single sided ramp for the overtravel. My machine doesn't get to the second ramp, it says overtravel when the first switch is activated. With the first switch activated the appropriate switch is on and the other off, but when two wires from the different switches are checked they are connected, ie as if there is a common feed to both switches, but one the other two wires are not connected, From what I can tell there is a common feed to both switches and the outputs are not short circuited, is this correct?

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Steve
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Re: Zeroturn Fanuc homing fault

Post by Steve » Sun 22 Nov , 2009 20:07 pm

Hi, Have a look at this thread as it tells the full story.

viewtopic.php?f=4&t=2444&p=8832&hilit=fanuc+home#p8832


I think this may be the answer.

OVERTRAVEL on a Fanuc machine.


Parameters 700, 701 and I think 703 and 704 are the positive and negative soft limits.

When you blanked everything I think you reset the encoder count position so the machine does not know where it is.

Now when you home it the counters think the position it was in when you reset is zero.

Everytime you send it to home the machine hits the soft limit before it gets there and trips out.

you could change the overtravels valuse to 9999999 and -99999999 then home it then reset the values.

Or I am told it is posible to press P and CANCEL together then power on and the soft limits are ignored until the machine homes.

Let me know if this works as its a usefull one to highlight if it does.

Martin
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Re: Zeroturn Fanuc homing fault

Post by Martin » Sun 22 Nov , 2009 20:58 pm

Power up with "P" & "CAN" pressed. The buttons are next to each other.
As Steve says this overides the software limits set in the 700 parameters until the machine is homed.

g-speed
Posts: 22
Joined: Thu 02 Nov , 2006 17:49 pm

Re: Zeroturn Fanuc homing fault

Post by g-speed » Sun 22 Nov , 2009 21:14 pm

I powered up the machine with CAN and P pressed and it has now successfully homed. Many thanks for your help.

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