Need Help!- Need help troubleshooting Frankenmill

[Colorado Greg]

New to the forum so I'm not sure if this the ideal place to post this but here it goes....

I've got a Wells Index unit from 1984 that at some point in it's life was retrofitted with a Fanuc 11 controller. Mostly it seems to be working but I've got a problem with the Z axis in the it almost always overtravels + when doing a G28 before I get started. I'm new to the CNC game and really want to get get started cutting but this is something I need to get sorted out.

I'm not even sure what people will need to know in order to help but I'm hoping someone can help me out!

A little more data, the controller says FS11M9A at the top during post, a manual would be a great thing if such a thing exists...

-Greg

[Dan Fritz]

Zero return on an 11M is complex, but it's pretty easy to adjust. Here's how it works:

The pulse coder inside the motor has a "1-pulse per revolution" signal. Every full turn of the pulse coder, a single pulse indicates that "zero" position. As the motor turns, you get one of these pulses every 5mm, 10mm, .200 inch, or whatever the pitch of the ballscrew is. Your first task is to find out how many inches (or mm) the machine moves per one revolution of the pulse coder.

Now, you also have some limit switches. There is an Overtravel limit switch that puts the control into the +Z OT alarm state. Find that switch by manually actuating it to trigger the +Z OT alarm.

Next, there will be a Z axis Zero-Return switch. This switch is actuated by a cam, which turns the switch on as it approaches the +Z limit, then it holds the switch on for a short distance, then it lets the switch drop off again. Adjustment of this cam's "drop-off" point is critical to proper zero-return function.

There is also a Zero-Return "Grid shift" parameter for each axis. For the 11M this parameter is #1850. To begin this adjustment process, first set this parameter for the Z axis to "0" so there is no "grid shift" in the Z axis.

To begin the adjustment process, first turn off the CNC control, then turn it back on again. DO NOT zero-return the Z axis yet.

Now, select the diagnostics screen and page up to Diagnostic #072. One bit in this register is for the Z zero-return limit switch (the one actuated by the cam). The 6th bit from the right should be a "1" normally, and should change to a "0" when you manually actuate that switch. Test it to see that the switch is working. Now SLOWLY jog the Z in the + direction until that bit changes from "1" to "0". Continue jogging in the + direction until the bit changes from "0" back to "1". This is the point at which the switch "drops off" the cam. Stop at that point and origin out the Z position (relative) display so that it reads "0.0000"

Now try to manually zero-return in the normal fashion. Jog away from the zero return position until you're at least 1 inch away from the zero-return cam switch. If you have a rapid override switch, set it at 25 or 50% so that rapid isn't so fast. Select Zero-return mode and press the +Z jog button to zero-return the Z axis. Watch the relative position display (the one you set to "0" at the point that the switch dropped off the cam). As the display passes this "0" point, it should go a bit farther before the zero return light comes on. This distance should be about 1/2 of the distance the machine moves with one turn of the pulse coder. If it's not, adjust the cam until it is. You'll have to turn the CNC off and back on again each time you make a cam adjustment and re-test. What you're looking for is a situation where the switch drops off the cam, goes 1/2 turn farther, then zeros out on the "1-pulse per rev" signal.

If the Z axis hits an Overtravel alarm before it zeros out, you'll have to back up the cam switch until it successfully zero-returns before hitting the OT switch. Once the cam is adjusted so the machine zeros out before the OT alarm, you'll need to fine-adjust the cam so the diagnostic bit changes from "0" to "1" at about 1/2 turn of the pulse coder from the zero-return point.

So much for adjusting the zero-return switch. Now, to fine-tune the zero-return position, you can go back to parameter 1850 (for the Z axis) and put a number in there that will fine-adjust the zero-return point. This shift amount can be a (+) or (-) value, and it is set in DETECT UNITS. A detect unit is how far the machine moves for one detect increment, which is a multiple of the pulse coder pulses. If the ballscrew pitch is in inches, your increment is probably .0001 If you have a metric ballscrew, the increment is probably .001 mm. You can only adjust the zero-return position as much as one turn of the pulse coder in either the + or - direction. Any more than that and you'll have to go back to adjusting the cam switch. DO NOT ATTEMPT to adjust the cam switch unless this grid shift parameter is set to zero!

If you have trouble with this adjustment process, please post the parameter values you have in parameter #1816 for the Z axis, and also the pitch of your Z ballscrew and the number of pulses/rev of your Z encoder. If the encoder is inside the motor, then the motor tag will have a "2000" or "2500" on it to denote the PPR of the encoder.

One last thing: Be sure the zero-return switch isn't "sticking" when it drops off the cam. A sticky switch can cause the zero-return switch to seek the next turn of the encoder, which will usually overtravel the axis.

[Colorado Greg]

Wow Dan, amazing writeup and I hope I can put it to use to sort this thing out. I've got a few questions and answers based off of what you have said.

#1. I pulled the cover off the top of the motor so that I could watch the pulse coder spin as I moved the Z. It does a full rotation in .1 inches.

#2. I pulled the cover off the side where the travel switches are and I see what you've described. There is a single lower travel switch and a set of upper travel switches. By manual actuating I confirmed the overtravel switches were the ones I expected.

Come to find, the cam that actuates the Zero-Return switch is loose and had a significant amount of play... well that answers some questions on what was going on eh? I've tightened and adjusted the cam to where it now triggers at -.057, that's relative to what I would consider Z home to be.

#3. You mention "Parameter #1850" which I am going to have to say I don't know what/where that is. I was able to find the diagnostic #072 and that operated as you said it would.

So, I'm making progress but some assistance on parameters would be great at this point. If you hadn't figured it out, I'm quite green at this

-Greg

Originally Posted by Dan Fritz Zero return on an 11M is complex, but it's pretty easy to adjust. Here's how it works: The pulse coder inside the motor has a "1-pulse per revolution" signal. Every full turn of the pulse coder, a single pulse indicates that "zero" position. As the motor turns, you get one of these pulses every 5mm, 10mm, .200 inch, or whatever the pitch of the ballscrew is. Your first task is to find out how many inches (or mm) the machine moves per one revolution of the pulse coder. Now, you also have some limit switches. There is an Overtravel limit switch that puts the control into the +Z OT alarm state. Find that switch by manually actuating it to trigger the +Z OT alarm. Next, there will be a Z axis Zero-Return switch. This switch is actuated by a cam, which turns the switch on as it approaches the +Z limit, then it holds the switch on for a short distance, then it lets the switch drop off again. Adjustment of this cam's "drop-off" point is critical to proper zero-return function. There is also a Zero-Return "Grid shift" parameter for each axis. For the 11M this parameter is #1850. To begin this adjustment process, first set this parameter for the Z axis to "0" so there is no "grid shift" in the Z axis. To begin the adjustment process, first turn off the CNC control, then turn it back on again. DO NOT zero-return the Z axis yet. Now, select the diagnostics screen and page up to Diagnostic #072. One bit in this register is for the Z zero-return limit switch (the one actuated by the cam). The 6th bit from the right should be a "1" normally, and should change to a "0" when you manually actuate that switch. Test it to see that the switch is working. Now SLOWLY jog the Z in the + direction until that bit changes from "1" to "0". Continue jogging in the + direction until the bit changes from "0" back to "1". This is the point at which the switch "drops off" the cam. Stop at that point and origin out the Z position (relative) display so that it reads "0.0000" Now try to manually zero-return in the normal fashion. Jog away from the zero return position until you're at least 1 inch away from the zero-return cam switch. If you have a rapid override switch, set it at 25 or 50% so that rapid isn't so fast. Select Zero-return mode and press the +Z jog button to zero-return the Z axis. Watch the relative position display (the one you set to "0" at the point that the switch dropped off the cam). As the display passes this "0" point, it should go a bit farther before the zero return light comes on. This distance should be about 1/2 of the distance the machine moves with one turn of the pulse coder. If it's not, adjust the cam until it is. You'll have to turn the CNC off and back on again each time you make a cam adjustment and re-test. What you're looking for is a situation where the switch drops off the cam, goes 1/2 turn farther, then zeros out on the "1-pulse per rev" signal. If the Z axis hits an Overtravel alarm before it zeros out, you'll have to back up the cam switch until it successfully zero-returns before hitting the OT switch. Once the cam is adjusted so the machine zeros out before the OT alarm, you'll need to fine-adjust the cam so the diagnostic bit changes from "0" to "1" at about 1/2 turn of the pulse coder from the zero-return point. So much for adjusting the zero-return switch. Now, to fine-tune the zero-return position, you can go back to parameter 1850 (for the Z axis) and put a number in there that will fine-adjust the zero-return point. This shift amount can be a (+) or (-) value, and it is set in DETECT UNITS. A detect unit is how far the machine moves for one detect increment, which is a multiple of the pulse coder pulses. If the ballscrew pitch is in inches, your increment is probably .0001 If you have a metric ballscrew, the increment is probably .001 mm. You can only adjust the zero-return position as much as one turn of the pulse coder in either the + or - direction. Any more than that and you'll have to go back to adjusting the cam switch. DO NOT ATTEMPT to adjust the cam switch unless this grid shift parameter is set to zero! If you have trouble with this adjustment process, please post the parameter values you have in parameter #1816 for the Z axis, and also the pitch of your Z ballscrew and the number of pulses/rev of your Z encoder. If the encoder is inside the motor, then the motor tag will have a "2000" or "2500" on it to denote the PPR of the encoder. One last thing: Be sure the zero-return switch isn't "sticking" when it drops off the cam. A sticky switch can cause the zero-return switch to seek the next turn of the encoder, which will usually overtravel the axis.

[fordav11]

press the SYSTEM button. It should show a list of items at the bottom.
press PARAM
now type 1850 and press NO.SRH. The screen should show parameter 1850 and values for X Y Z and A B C if you have those axis's

[Dan Fritz]

To look at parameter 1850 (or any parameter), press the soft-function key labeled "System". You should be able to find a page of parameters, then page up until you get to the number 1850. The values in these parameters are locked, so you can change them until you press the SETTING key, page up to setting #8000 and enter a "1" bit in the "PWE" (Parameter Write Enable) position. That generates an alarm #100, but it also lets you go back to the SYSTEM/PARAMETER page and make changes.

To change any parameters or settings, you must be in MDI mode, and the memory protect key switch must be turned off. Stuff on the SETTINGS page can be changed without turning on the PWE bit, but parameters can not. When finished, go back to Setting #8000 and turn off PWE, then press RESET to clear the alarm. Changing SOME parameters require that you also turn the control off/on again to make the new parameter effective.

Hope this helps.

[Colorado Greg]

Hmm, don't have a SYSTEM option at the root menu, I do have a SETTING and SERVICE menu item.

Ahhh, but I just found that if I go to SERVICE and then use INP_NO. I can type in 1850 and then I see the setting. Interestingly enough, now that I've done that when I page through the various SERVICE screens I see a LOT more values that I didn't see before.

I'm learning more about this thing every day!

Now to run errands and then I'll get back and finish doing the other steps and see if I can make it work right.

You guys rock, I was about ready to take up decoupage

-Greg

Originally Posted by fordav11 press the SYSTEM button. It should show a list of items at the bottom. press PARAM now type 1850 and press NO.SRH. The screen should show parameter 1850 and values for X Y Z and A B C if you have those axis's

[Colorado Greg]

Found the setting but it keeps telling me I'm write protected when I try to change the PWE bit to a 1. I'm in MDI (I tried edit as well) and I've got the key set to turn off program protect.

I've attached a picture of where I'm at.

-Greg

Originally Posted by Dan Fritz To look at parameter 1850 (or any parameter), press the soft-function key labeled "System". You should be able to find a page of parameters, then page up until you get to the number 1850. The values in these parameters are locked, so you can change them until you press the SETTING key, page up to setting #8000 and enter a "1" bit in the "PWE" (Parameter Write Enable) position. That generates an alarm #100, but it also lets you go back to the SYSTEM/PARAMETER page and make changes. To change any parameters or settings, you must be in MDI mode, and the memory protect key switch must be turned off. Stuff on the SETTINGS page can be changed without turning on the PWE bit, but parameters can not. When finished, go back to Setting #8000 and turn off PWE, then press RESET to clear the alarm. Changing SOME parameters require that you also turn the control off/on again to make the new parameter effective. Hope this helps.

[tc429]

see where it says " parameter (service)" at the top? theres another screen tagged "parameter (setting)", you must go back to your setting/service and select 'setting' to set pwe, then go to service to change everything else...kinda goofy, yes...

you'll note service lists all the parameters, setting just repeats a portion of them- like Dan said, 'setting' pages dont require pwe to adjust- thats why you can set pwe from there, but not from the service side (i think you can turn it off from service though...wasnt one of fanucs better ideas)

[gbowne1]

If you need manuals, They're avalialble from FANUC. Usually $15-$40. You can also get them on eBay if you are willing to pay for them. Sometimes they are not cheap. If I'm right here are the manual numbers for the FANUC 10, 11 and 12. The GE FANUC versions start with the GFZ- numbers and the FANUC LTD version start with B- but they are usually the same print.

GFZ-54824E
GFZ-54815E
GFZ-54874E
GFZ-54814E

As you can see most of them start with -548xx numbers. I might be able to help with other manuals if you need one.

[Colorado Greg]

Ah, how fun is that... a way to see the setting *think* you can edit them but not edit them. I'm super excited by that!

However, you were spot on and I was able to change the setting, thanks and I'll keep in mind the "have you tried getting to the setting from another place" as a solution for the future!

Now that I've played with this thing for the last hour I sorta understand what's going on and I can reliably tell the machine to go home on Z and it doesn't overtravel on the Z. However.... I'll post the current issue in a moment but thanks for the help

-Greg

Originally Posted by tc429 see where it says " parameter (service)" at the top? theres another screen tagged "parameter (setting)", you must go back to your setting/service and select 'setting' to set pwe, then go to service to change everything else...kinda goofy, yes... you'll note service lists all the parameters, setting just repeats a portion of them- like Dan said, 'setting' pages dont require pwe to adjust- thats why you can set pwe from there, but not from the service side (i think you can turn it off from service though...wasnt one of fanucs better ideas)

[Colorado Greg]

Ok, after much yutzing with the cam and getting it tight I can pretty reliably tell the machine to go to Z home and not overtravel. "pretty reliably" however seems like "not working right yet" though.

I have a pair of items, one might be normal, the other not so much.

#1. If I have the machine at zero when I power it up it will overtravel if I tell it to go to zero. Since the cam is past the actuating the switch I am not actually too surprised by this. However, it seems odd. Is this how these machines function? Don't park it at home on the axis or move of home before you home it? This is more than likely an operator/newbie error but I would like to know so I don't continue to do a wrong thing.

#2. It seems that the travel to Z home is not consistent. I have a witness mark that I have been watching and if I rapid jog the Z down and then zero return it from the panel it seems to be creeping higher every time. If I power cycle it starts that over again. I would think it would figure out where zero was and hold that.

A little further data, the 1850 setting was "2200" for Z, the other two axis were set to "0". I've change the 1850 for Z to "0" as well, honestly I can't see/tell a difference. It seems that the travel after zero-return switch is somewhat arbitrary.

-Greg

[gbowne1]

Yeah, you have to watch what screen your in when parameter setting.

There are two different ones Parameter [Service] and Parameter [Setting].

I generally don't park any axes at it's home before re-homing. The idea is to let the control find it again. I've found it doesn't do that very well if you're already on home.

It could be that your Z is creeping a bit. See what is supporting your Z, and make sure it's not loose or that the machine gibs are not too loose or too tight.