Denford Software & Machines

Please see previous post first, which should read X axis, not Z in the title. Post subject: Z overtravel alarm on Cyclone Fanuc OT.

After last post, machine worked using the P & CAN procedure. Last night produced 13 items, turned lathe off and went home.

Tonight, turned the Cyclone on, followed procedure to Home X axis, slide moved to top position and Fanuc went into error state, but only showing "Not ready" this time, not overtravel like it did last time. Moved slide by pressing overide button on side of machine, tried to home again, but same problem.

Switched all power off, pressed P & CAN, tried to home, but got the same error message.

Z axis will home ok

Any help or advice welcomed to resolve this matter, that could only happen when items need to be finished and delivered by the end of the month !!! November, that is..........

Bob

This is what I believe happens with the Fanuc systems:

Axis overtravel limits +ve and -ve are set in parameters for each axis.
When the control is powered off it remembers the axes positions and therefore thinks it know when the slide has gone past these limits even before it has homed out. So, if an axis happens to move while the control is off then you may well hit the software overtravel before the machine has time to hit the home switch. (eg: the X axis may be slowly dropping during the night)
Holding the PQ and CAN key on power up tells the Fanuc not to remember the axis positions hence letting you home out again - ignoring the software limits.
Not ready alarm is usally in indication that e.stop or an overtravel limit switch has been pressed, or there is a drive fault

Hope this makes sense - if you were desperate to get the machine running and P+CAN dosn't seem to be working, you could alter the software limits to -1 and +1 to disable software limits (see here: viewtopic.php?f=15&t=2487)

Take a look at the datum X axis datum switch & check that the Fanuc control is reading the signal in the diagnostics.
It sounds like the X is not detecting the datum signal & then hitting the overtravel switch.

Hi
Thanks for the reply.

I did look at the X datum switch previously, a wire was loose, and then fell off, along with the screw. This was replaced and the switch refitted.

Rightly or wrongly, I carried out a manual test, by homeing the X slide, and depressessing the switch manually before the slide reached it. This made no difference to the slide going into overtravel alarm, as noted in the first post referred to at the start of this thread. I thought the switch may be faulty, but when the P+CAN worked last time, I figured I was on the wrong track?

Regards
Bob

Martin wrote:Take a look at the datum X axis datum switch & check that the Fanuc control is reading the signal in the diagnostics.
It sounds like the X is not detecting the datum signal & then hitting the overtravel switch.

Not sure how to see if it is working in diagnostics?
Bob

The datum switches can be seen on the first diagnostic page. They are around 16 bit 4(X), 17 bit 4(Z). it may be easier to work out which one is the Z then the X will be the one above it.

Rightly or wrongly, I carried out a manual test, by homeing the X slide

Another thing I remember, vaguely, about the Fanuc homing sequence is that it had to be done at full speed otherwise it wouldn't work - I'm guessing that you turned the feed override down while testing it by hand ?!

Hi

Yup !!!!

Saturday will be the day to take on board all the advice offered and put it to the test.
Thanks all
Bob

Hi Bob

Couple of points to always remember with the Fanuc OT control, ALWAYS leave the turret OFF the Home position when you shut down, I always wind the X and Z axis well away from the "stops" when shutting down for the night.
Should always be at least 40mm away from home.

Also always turn the feed override down to around 50~60% before you home, although the system does slow the Axis down about 40mm from the actual Home position if you have left it at the Axis home position the first thing the system tries to do is move in full rapid mode and of course if the turret is already there then it just goes straight into overtravel situation.

In later O series "D" and "F" the machine will actually move away from the "Home" position if you have left it too close and then come back and home correctly but you won`t have that nice "extra"!!!!

Regards
Rob

.

Hi

Studied the diagnostics page today, established which one was Z axis, and noted differences before and after homeing that axis. Following the advice from here, noted the difference, or lack of difference for the X axis after home signal. There was no difference , and machine alarmed out again.

Now the good news, Removed the cover from the X Axis slide to check the microswitch, and the problem was visibly obvious. The slide had hit the roller on the microswitch, and bent the whole roller and its arm back on itself, so it would never make contact with the actual pin of the switch. This switch must have either moved or was just on the borderline of being in the right alignment, OR, my slide does have a problem, which would also explain the inabillity to part off sucessfully.

Removed switch, straightened arm, replaced switch, did P+CAN, and bingo !!! Back in action.

No visible shake in slide, although the gib strip does protrude about 6mm below the slide casting?

For those who are interested, I found a cyclone with a bar feed for sale: https://www.newengland.co.uk/for-sale/
£2750
Thanks all
Bob