[koch.Cnc]

Hi,

Im having some homing issues on my Fanuc O-MD vmc, I have no problem homing the X, Z, B axis, But every morning that I power-up the machine and home the Y axis, the machine travels very slowly compared to the other axis, and stops at about 150-200mm before the limit switch, and homes *Correctly* in the wrong position, I have been able to correctly home the machine In which I turn the machine off after it found the *False* Home, press P + CANCEL during power up and send the machine again to home in Y.
This way The machine works ok, but it is a hassle every morning.

I think it has something to do with a gridshift parameter, But I have little experience of how this works, I have tried looking for a solution in this forum and in google but I wasnt lucky..maybe someone is.
I would be very thankfull if somebody could point me in the right direction.
Thank you !

[guhl]

most likely your orgin swith is open (wire broken or something else)
check diagnostic parameter 17 bit 5 (third from the left)

[ifixcnc]

I agree with guhl that it seems like a switch problem as it is in creep feed before it hits the slow down dog. I think on a 0MD you will check that with an X bit and not diagnostic. If it is some thing to with soft limits (thats what Cancel P clears) you may want to just change grid shift or stored stroke by a little bit and see if this helps.

[koch.Cnc]

Hi,
Thanks for the fast reply @guhl, I checked out Diagnostic bitX0017 before homing and it Displayed 10000000, After turning the machine on and off (P+Cancel etc) and managed to home the machine BITX0017 displayed 10100000. After I manually moved the position so that the machine was somewhere else and not activating the homing switch BITX0017 was once again 10000000, My guess would be that the homing switch is working?
I checked the switch with a Multimeter, and the readings were ok, Now im not sure if I should place an order for a new switch...
In the meantime, @ifixcnc , could you help me with the parameters for both the gridshift and stored stroke for a Fanuc O-MD ? Also is there any special procedure while changing the parameters?
Thank you!

[ifixcnc]

Is your control an i ? What machine do you have.

[koch.Cnc]

@ifixcnc my control is a Fanuc 0-MD , its not a fanuc 0i-MD, and the machine is Feeler 1000 VMC.
Thanks,

[ifixcnc]

Check parameter #1815 and let me know what is there.

[guhl]

check on what pins cable sits they are most likely must be normal closed, compare with signals 15#5 and 16#5
check state of limit switch on itself and then check state on wires in control box
may be you cable frayed in place where you usually works and works properly in other areas

[koch.Cnc]

@Ifixcnc I was looking for parameter #1815, but the last # is parameter 1139 and then it skips to 2000.
@Guhl Im not so sure what you mean, But I already checked the limit switch in several positions and the switch seems to be ok, the machine also homes with no problem.
Thank you guys for helping out, Im trying to find out which parameter is the gridshift parameter, I think it has to do with this..

[guhl]

I meant this:
checked out Diagnostic bitX0017 before homing and it Displayed 10000000, After turning the machine on and off (P+Cancel etc) and managed to home the machine BITX0017 displayed 10100000. After I manually moved the position so that the machine was somewhere else and not activating the homing switch BITX0017 was once again 10000000
I would find out what type of switch used, NO (normal opened) or NC (normal closed). Usually they use NC. In this case if you have 10000000 in X17 your Y axis creeps at slow speed until axis reaches the origin. Switch wherein must change its state to inverse. 10100000

[underthetire]

I believe its in the 500 parameter range, no 1815 on 0 control, that was 0i, 16/18 etc. I'd pull covers and do a visual, ive seen this many times before from wads of chips false triggering the switch, or even bent switch brackets doing this.

Sent from my G-Tab Quantum using Tapatalk

[koch.Cnc]

Thanks @underthetire I forgot to mention that I am currently on a business trip... as soon as I get back to work...around the 14th of next month I'll check this. Thanks!

[koch.Cnc]

Hi!,
I'm back from my business trip, I wanted to say that I replaced the Limit switch and the machine is homing correctly now.
this is weird because I have tested the old switch with an Ohmeter and everything is ok.
Although I still have the problem that the machine is still homing x and z with a normal homing speed and the Y axis is still very slow but Homing correctly..
maybe somebody has an idea what the problem might be..

[ifixcnc]

Sounds like a wiring, connection or I/O problem. If it is better but not right, it seems that the new switch may have a better contact. That would change the condition.