Fanuc 0m-c veeeeery slow rotaion
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  1. #1
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    Default Fanuc 0m-c veeeeery slow rotaion

    Hello all
    I have very old 3-axis mill with FANUC 0M-C control, and now I am facing strange problem.

    When I execute M03, the spindle starts rotating very slow (around 2 RPM) no matter of speed setting.

    I think the spindle motor and cotrol board are not damaged, because in tool changing cycle, the spindle positions itself quickly as allways, and also rotates the umbrella type magazine with normal speed as allways.

    Before this problem appeared, I was setting some serial port related parameters, then uploaded the CAM enerated program. This program was the first which rotated the spindle so slow, although normal speeds like S1500 are only specified in it. Since then, I am not able to spin up the spindle in MDI, nor original programs which used to work, nor new programs, it still keeps its 2 RPM.

    The machine suffered all settings loss, due to empty batteries, but we were somehow able to make it work (mostly) again.

    I will be gratefull for any idea what can be wrong with it.

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    Couple of questions:

    Do you have a record of what serial port parameters you set?

    Is G96 or G97 active?

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    Thanks for advice, but G96 and G97 are both inactive

    I had been checking the serial comm params according the manual, and If I remember correctly, I have only changed the format from EIA to ISO. Tomorrow i will try to set it back, just in case.

    Another observations:
    - The spindle in CCW direction rotates at cca 2 RPM, but in CCW it runs visible faster, lets say 5-10 RPM.
    - When changing the tool, the spindle rotates the umbrela magazine at normal speed both directions.
    - On MDI screen, there are only last two numbers of S value visible (for example when I set S1500, it shows S 00, in case of S 2345 it shows S 45) but real speed of the spindle is allways 2 RPM.
    - I have switched the parameter on, for displaying the speed and the tool in lower right corner. S shown here is allways 0, T is always real number of tool.

    AC spindle motor is type A06B-0753-B190
    Spindle control board is type A16B-1100-0200


    Any thoughts ?

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    Compare parameter 62 bit 3 and parameters 539 through 543 to your original settings. These are some basic spindle speed control parameter for an analog spindle interface. There are other interface types too, so many possibilities.

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    Unfortunatelly, I haven't saved the original settings before I set the serial communication.

    Setting params 539 through 543 according the manual didn't have any effect. Are they for analog drives only ?

    My spindle controller is serial type 3S. The control board contains the numeric diplay, which shows actual RPM. In my case it shows 1 and 8 respectivelly, which somewhat corresponds with real RPM. Maybe the control board and motor just do what they are commanded to do and problem is somewhere in PMC (parameters, ladder, ... ???)

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    I am still struggling bringing the machine back to life.
    Checked the control voltages on spindle board and found nothing incorrect there. Checked the motor, also faultless. I am pretty sure now, tha problem is in CNC, maybe caused by some incorrect parameter.

    Could enybody please send me the parameters backup from any machine with 0m-C ?

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    Quote Originally Posted by VinH View Post
    .....Could enybody please send me the parameters backup from any machine with 0m-C ?
    You need parameters from the same builder and model of machine.

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    It would be very happy coincidence if someone had the backup of parameter which I could just uload and try. So my plan is to manually compare each parameter to mine, on every difference check the param meaning with documentation and decite which value is more likelly correct.

    But I still need at least something to compare with.

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    Could a parameter have been changed that has to do with how decimals are handled? Maybe the control is interpreting S1500 as S1.500?

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    It could be, but it rotates always the same RPM, no metter if I set S9000 or S1000.
    Only when rotating the tool magazine and positioning for tool change it rotates normal quick speed.

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    Quote Originally Posted by VinH View Post
    It would be very happy coincidence if someone had the backup of parameter which I could just uload and try. So my plan is to manually compare each parameter to mine, on every difference check the param meaning with documentation and decite which value is more likelly correct.

    But I still need at least something to compare with.
    Great idea, but it most likely that the problem is in the PMC parameters whose functions are determined by the machine builder, not Fanuc. Comparing PMC parameters between machines from different builders will not work.

    Does your machine have a 2 speed headstock (geared head) or single speed belt drive?

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    Of course the this method is not guranteed, but I don't know of any better. On the other hand, there is not so many params which define the basic control of the spindle (20 or so I guess). The problem is the documentation is not very clear about values and their meaning.

    Quote Originally Posted by Vancbiker View Post
    Does your machine have a 2 speed headstock (geared head) or single speed belt drive?
    None of theese, headstock is directly connected to the spindle motor shaft, and the rpm sensor is built in the motor.


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