Fanuc OM forgets G54?

APM · Oct 1, 2013

We've got a Makino FNC 60 that we've run for about 6 years now. All of a sudden it will run a program once, flawlessly, then after the operator changes the part and hits cycle start to run another part, it goes to an entirely different and seemingly random G54 position. It executes the program just fine, but starts at a different G54 everytime you hit cycle start. X and Y axes are different each time. It's driving us crazy, does anyone have any ideas of things to check?

Thanks,
Greg

NAST555 · Oct 1, 2013

How far is it off? Is it the same incremental distance every time? And are you cancelling all offsets, but I would think that M30 would do that, at the end of the program?

bullandbladder · Oct 1, 2013

Can we see your program?
Is it an existing prog you've run before?
Does the same problem occur with all programs?
G91 where there should be G90?

APM · Oct 1, 2013

It is off a different amount each time. It goes to a random and unpredictable position each time.

Greg

Rstewart · Oct 1, 2013

See your program, or at least the start and the ending?

XD341 · Oct 1, 2013

If you hit reset before cycle start does it run properly?

sable · Oct 1, 2013

Is G54 called after every toolchange?

Do you go to home position for toolchange?

Does the machine home onto a dog or does it have position encoders?

Does the machine always set off in the same direction or does it sometimes hit the stops when this problem occurs?

What about G55 ,6,7 etc ,are they OK.

Have you tried other programs?

Do you reset the position of G54 after it has gone wrong or does it work again for a while?
Just trying to get a better picture of what is going on here.

John Welden · Oct 1, 2013

Fanuc is soooo reliable.

Curt B · Oct 1, 2013

Some Fanuc controls have a button marked ABS and usually on the screen somewhere you can see "ABS" switch to "INC" when you touch it. When in inc mode offsets will incrementally double up at program execution. I'd like to slap the guy who designed that booby trap as many times guys have come to me saying the machine is not positioning properly and that button is the culprit.

XD341 · Oct 1, 2013

John Welden said:
Fanuc is soooo reliable.

I kinda have a love/hate with Fanuc. The control isn't easy to use, isn't the highest performance, and lacks many time saving features of other controls.....but, it's what I have and what I know. I will say that Fanuc is extremely reliable. It's not the best but reliability isn't the problem.

John Welden · Oct 1, 2013

XD341 said:
I kinda have a love/hate with Fanuc. The control isn't easy to use, isn't the highest performance, and lacks many time saving features of other controls.....but, it's what I have and what I know. I will say that Fanuc is extremely reliable. It's not the best but reliability isn't the problem.

Reliable compared to what?

XD341 · Oct 1, 2013

Curt B said:
Some Fanuc controls have a button marked ABS and usually on the screen somewhere you can see "ABS" switch to "INC" when you touch it. When in inc mode offsets will incrementally double up at program execution. I'd like to slap the guy who designed that booby trap as many times guys have come to me saying the machine is not positioning properly and that button is the culprit.

Yeah, I have an older OM and I was curious if a sub program (i.e tool change) was leaving the control in INC mode, hence the reset to send it back to ABS or slap a G90 in there after a tool change and see if that helps....post up your code, that would be the easiest. I can almost guarantee that this isn't a hardware problem.

XD341 · Oct 1, 2013

John Welden said:
Reliable compared to what?

Damn it.....you hooked me.....

Reliable compared to pretty much everything else in my shop, air compressors, punch presses, computers, heaters....in 15 years of running Fanuc controls I've had only one "control" problem and that was a y axis drive on 10 year old mill immediately following a lightning strike to the building. Did the lightning have anything to do with it....I dunno. But I've only ever had one problem. I don't enjoy working with fanuc controls.....at all....but reliability just hasn't been a major factor.

John Welden · Oct 1, 2013

XD341 said:
Damn it.....you hooked me.....

Reliable compared to pretty much everything else in my shop, air compressors, punch presses, computers, heaters....in 15 years of running Fanuc controls I've had only one "control" problem and that was a y axis drive on 10 year old mill immediately following a lighting strike to the building. Did the lighting have anything to do with it....I dunno. But I've only ever had one problem. I don't enjoy working with fanuc controls.....at all....but reliability just hasn't been a major factor.

They're reliably a pain in the ass to use.

XD341 · Oct 1, 2013

John Welden said:
They're reliably a pain in the ass to use.

I agree. 100%

APM · Oct 1, 2013

Hey guys,
Thanks for all the input. We have tried some of the ideas listed here with no success. Most of you want to see the program. That would be no problem, but it's not just one program. We hand type all the the programs on this machine as we have for the past six years, and have never run into this before. To diagnose the problem we wrote a simple go to and return home program with no spindle or coolant, and it works only once after the initial power up. The go to program may respond exactly right every time until I hand jog the machine one way or the other, and then the control has no memory of where it should be going. It does however have memory of where it came from. If I origin X,Y, and Z then try to operate the machine it doesn't lose track of how far it is from home. the zeros all remain the same if I zero return again. The machine does power up to a dog instead of a reading from the encoder, but I don't think this is the problem. Part of the reason we won't even run it however is because it will lose it's sense of location in all three axis. On more than one occasion the Z axis has buried the tool into the vice. If I watch it closely even the distance to go will show Z minus 21 inches or some crazy number like that.
Any more input or advice will be greatly appreciated, and thanks again for the time you've already put into my problem. I will sleep better at night when we finally figure this bug out.
Greg

Sub-Micron · Oct 1, 2013

Try using G92 for now. It's "old school", but might get you going.

Ox · Oct 1, 2013

I have had 2 Fanuc's (newer than yours) pull some funny going's on before in regards to code in existing progs.

The fix for both has been to dump the library completely and start fresh.
If you have been hand coding new progs in for 6 yrs, is the memory getting more and more full, or doo you dump off old progs as you go?

Never seen what you are experiencing tho.

Just to confirm, this is an "0" and not an "0i" right?

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

Think Snow Eh!
Ox

HuFlungDung · Oct 1, 2013

Sub-Micron said:
Try using G92 for now. It's "old school", but might get you going.

Or, if G92 has been used in some program (without understanding how G92 works), it could also be the problem. G92 moves all the other coordinate systems except for G53 (if it exists on that control).

metaltech · Oct 2, 2013

Look for a function called "Manual Absolute". There could be a menu screen that shows, or a hard switch (like a toggle) or a software switch like a keep relay in the PMC. The MTB decides how to interface it, so that's why several possibilities. If you find it, and it's off, home the axes then turn it on. DON'T turn it off, there's no good reason for not using it.

I would suggest NOT using G92. That will shift all work offsets, and if you don't know how to properly use it, you'll only chase offsets worse. It's needed on old controls without work offsets, but I see no reason on your machine to use it.

Fanuc OM forgets G54?

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