Fanuc 6m, lost my Y axis and no error code

[rolandkra]

Hello to all,
I have an old Okuma Howa Millac 4 H (horizontal machining centre with pallets) and it's been "resting" for some years but now I'm resurrecting it. After I bought it at auction 3 years ago, I spent ages to clean out the solid waste that blocked every moving thing and did manage to get it running, sort of. X, Y, Z and the pallet changer all worked but I was missing some manuals and couldn't work out the tool changer.

Well it's time to try again and so far I've managed to wake it up again and have everything but the Y axis working. I can't move it by any means and it causes no error signals that I'm aware of. It's as if there was no Y axis at all. I can't zero reference it and have no joy with the hand wheel, jog or g functions. When I try to zero reference it, there is deathly silence

I can successfully run programs that use everything else. If I sneak in a line for a Y move, the program stops and helpfully advises me that I have a ref return error, but, of course I did know that.

When trying to turn the Y axis screw I get a humming and strong resistance so I think the brake is working.

There are two green LEDs lit up on the motor drive board just as on the Z and X boards.

I noticed that the spindle drops a few millimetres each time turn off the power so I think the Y axis brake releases for a fraction of a second.

At one stage when I ran the X into soft alarm I also got a 427 alarm for the Y but that's it and only the once.

After reading many of the other posts here I've checked some things such as way lube and soft alarms. Would anyone have any ideas where to go from here?
regards, Roland

[guhl]

Changeover plugs on drives and try to move Y axis as any other axis or try to swap over the boards. But in last case don't forget about jumpers and pots.

[rolandkra]

Originally Posted by guhl Changeover plugs on drives and try to move Y axis as any other axis or try to swap over the boards. But in last case don't forget about jumpers and pots.

It looks like the boards for X and Y are the same except that the Y board has two other wires attached to the top.

Both pairs of plugs are the same so do you suggest that I just move the Y axis plugs to the X axis board and the X to the Y board and use the mpg (handle) for a short move?

In the event it does move we can look deeper.

[guhl]

Yes, you're right. Use MPG or JOG with low level of feedrate.
I faced with similar problem, but had no moving of Z and Y axes. The problem has been fixed after I swapped over the boards. Then I returned boards back.
Seemingly, problem was in connections.

[rolandkra]

Hi,
No luck with changing over the boards as all kinds of errors come up.
If I unplug anything to do with Y axis I get an error so I think the Y board and motor are OK.

The situation now is;
Can jog and use hand wheel and use g28 to send X and Z home but nothing happens to Y

In MDI when trying G28 for Y it just waits... and no alarm

So I think that whichever section is telling Y to move is faulty. (the messenger has fallen asleep :-) )
Any more thoughts?
Roland

[guhl]

Which errors do you get when change the boards?

[BodylinezCNC]

I would guess that your encoder is not working properly, or you have some faulty wiring.

This could be something as basic as a loose connection, or an improper pulse signal syncronization with the reference counter.


Brent

[Al_The_Man]

The fact that your drive resists movement suggests the drive is active, it appears to me that the drive is not enabled in the controller somehow?
If you select jog or handwheel for the Y, see if the Y position display changes.
If the display does not change then most likely the control does not expect the servo to move for some reason.
The display normally shows the expected position, not the actual servo feedback position.
When the display changes but the servo does not move, you will reach a point where it will declare a following error.
Al.

[BodylinezCNC]

Another thing I would do is check the diagnostics and parameters to see if the encoder sensors output and input valid readings. If they are receiving invalid codes it might turn off the output drive.

Brent

[rolandkra]

Guhl, I'll check which errors come up once I get in to work later today, but it seems to say the motors are unable to be swapped on the boards. The Y motor is double the length of the X motor and , as you mentioned earlier, all the jumpers and pots would require altering and I didn't want to do that yet.
Roland

[rolandkra]

Originally Posted by Al_The_Man The fact that your drive resists movement suggests the drive is active, it appears to me that the drive is not enabled in the controller somehow? If you select jog or handwheel for the Y, see if the Y position display changes. Al.

Originally Posted by BodylinezCNC Another thing I would do is check the diagnostics and parameters to see if the encoder sensors output and input valid readings. If they are receiving invalid codes it might turn off the output drive. Brent

Hello Brent and Al,
I have nothing showing on the display output when I try to move Y and it does seem that there is no expectation of anything happening, so no alarms

There is a possibility of lost parameters as, although this has a bubble memory, which I think means that batteries aren't required, it also has another black box (possibly called a sequencer and possibly part of the Okuma Howa side) that had some decayed batteries on it. perhaps it's just luck that I didn't lose any other capabilities.

I'll check in the Fanuc manual if I can do something with parameters.
Roland

[Al_The_Man]

Originally Posted by rolandkra I have nothing showing on the display output when I try to move Y and it does seem that there is no expectation of anything happening, so no alarms

That would seem to indicate that there is nothing physically wrong and the controller does not expect the servo to move, hence no alarm.
I had one instance on a 6m where one axis parameter got corrupted while the machine was sitting idle for and hour.
Plugged the correct one in and it has been fine ever since.
If you have the parameter listing, step through and see if there is any discrepencies.
Al.