Absolute Encoders

A buddy has several SuperMax mills with Fanuc OT controls. Different times, usually from power outages, he has to hold in "P" and "CANCEL" at power-up
to get the machine to home at proper position, then he's fine. He actually says he holds in 3 keys but I only remember "P" and "CANCEL". The problem is he now has an identical homing problem with his SuperMax lathe which has a Fanuc 10T control. Is there a similar procedure for the 10T to get the machine to home back to original position? Any help is appreciated, Bart
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Fanuc 18mc is letter "O","P", "Cancel" Don't know if this works for 10T.
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Thanks for the reply alphonso, any idea where and in what manual this procedure is described? Maintenance? Operator's? Thanks again, Bart
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Not in any manual that I know of. The first time this happened to me, I called the dealer of the machine and he gave me the sequence. He also said he didn't know of a manual that has the info, he got it from Fanuc.
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Check the backup batteries. He shouldn't have to do this from power outages.
ca
bborb wrote:

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Hey Clay,
I sent you a PM, but don't know if you received it. I've got a good encoder guy that wanted to go over the info you asked about.
John
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Neither of those machines have absolute encoders, otherwise they wouldn't be grid shifted at power up.
IIRC, on a 10T control you power up holding "-" and "." (minus and decimal point) keys. Then a menu will pop up that gives you some choices. It's been a very long time since I've played on a 10T, so it's just as likely that this will clear the memory.
In a pinch, you can turn the ball screws by hand while the machine is powered down. Bring the axes within 10mm or so of their home position and you should be able to zero return them without an overtravel alarm.
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Dan

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Ya..the procedure is entirely different for a control with absolute encoders. Fanuc makes it a major pain in the a** to reset one of those. Why in the h*ll they couldn't just put a softkey in a menu on the control like Siemens does is beyond me.
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Anthony

You can't 'idiot proof' anything....every time you try, they just make
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Hmph. Our machines have Fanuc controls and they do have a key for zero return. It's probably another one of those things that is left up to the builder and most will take the path of least resistance and not provide that function. But there is a procedure that goes along with the ZRN.
Tsugami puts index marks on the machines and if you lose zero all you have to do is line up the index marks, jog about 30mm away then back toward the index marks stopping 5mm away, change a keep relay (k00.7 on an 18i) from 0 to 1, hit the ZRN key or rotate the selector to ZRN depending on the model, then jog back towards the index marks.
If you do it right it the control will see the zero pulse signal from the encoder and reset zero automatically (and stop there). You just check to see that the index marks are lined up. The marks will be either lined up or one pitch of the ball screw apart, so it's easy to see. Turn the keep relay off and you're done.
If you stop your jog too far away or too close, zero will be one revolution off and you have to try again.
I had a machine at a show that had dead batteries and I did this every morning for all six axes in less than 10 minutes. I was too far away to drive to a Fanuc office to pick up a set and I sure wasn't about to pay them to have a service tech drive the batteries out to me.
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Ya, possibly. On ours there is a procedure whereby you have to set the axis bit in 1815, power down, power up....physically set the axis, reset the bit in 1815, power down, power up.....etc etc etc Whole lot more trouble than hitting the 'preset' button, typing in the physical position, 'enter' 'ref key' "Axis + key" done. (on some of the older controls, it's just 'preset' 'value' 'enter' done.
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Anthony

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We call that "forcing the bit". It works on our machines too but it's a PITA. You need to be able to force the axis to zero though if you say replace a ball screw or a servo motor. In those cases the factory set zero position is likely not valid anymore.
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Yup, or when for some as of yet unknown reason, the control just dumps the SRAM. Had a 21iT do that the other day, all the custom screens and what not...just gone, no obvious reason. Batteries were fine. The control just puked of it's own accord. Reloaded everything from a recent backup, re- taught all the axis and it's ran without a glitch since.
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Anthony

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Regarding 10T soft limits:
One way is, in fact, to enter the IPL mode using minus and decimal point on power up. This brings up a menu. Choice #4 asks a question - I'm pretty sure the answer is no but either answer won't hurt anything. Exit IPL mode by entering 99. When the machine comes on, there will be no soft limits until the next power up. Do a normal zero return.
Hand cranking usually won't help this problem because it almost always happens on axes with electric brakes that allow the axis to slip on power down. The locked brake keeps you from hand cranking.
Another way is to go into the parameters and put all 9's in the plus limits and -9's in the minus limits. On the next power up, the soft limits will be very large.
Good Luck,
Warren Uptime Electronics, Inc.
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