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  1. #1
    Join Date
    Oct 2007
    Posts
    5

    21iT pitch error compensation

    Hello All;

    I joined this site because it returned the only useful hit on Yahoo regarding setting the pitch error compensation in the above mentioned control. I can access the parameters in the machine, and I think that I understand how to do it from reading an older fanuc manual but I would really appreciate some proper info on doing the job. The problem that I am seeing is approximately 00025"/" excess travel on the X axis measured as a radius not diameter. The problem seems to be linear based on measurements that I have made. All other contributing factors have been eliminated such as headstock alignment, cross slide alignment, tool center height etc. Thanks in advance and hello as well.

    Glenn @ Metro North.

  2. #2
    Join Date
    Nov 2005
    Posts
    219
    what about the back lash parameter ??? Did you check that???

    I have no idea on pitch error, sorry.

  3. #3
    Join Date
    Oct 2007
    Posts
    5
    Backlash would account for error only if changing direction of motion. I am measuring the error when moving the X axis in one direction only. Thanks for the input though.

    Glenn

  4. #4
    Join Date
    Nov 2005
    Posts
    274
    Quote Originally Posted by metronorth View Post
    Backlash would account for error only if changing direction of motion. I am measuring the error when moving the X axis in one direction only. Thanks for the input though.

    Glenn
    Setting your Pitch Error is difficult to do and should be done with a laser. You need to collect the data as the head travels every so many leads depending on the total travel. The laser compares the amount of travel with the amount that was asked to travel and then gives you your comps per specified lead. You need to contact some one that specializes in this. Like the MB or anyone that sells CNC machine tools should have the means to set them.
    It would be difficult to just divide the total error by the number of leads and then spread it evenly across the comps. You may have most of the error with in a small amount of travel.

    Bluesman

  5. #5
    Join Date
    Oct 2007
    Posts
    5
    bluesman;

    The research that I have done so far seems to indicate that the pitch error comp value is applied proportionally to the distance that the axis moves from one point to the next. Since I have a very linear error, which I have measured carefully throughout the length of the stroke, I am hoping that I can set a minimum point at the extreme X- end of the axis travel, a reference point and a Maximum point at the extreme X+ end of the axis travel. If my understanding is correct, the error correction amount will be added in proportionally from one comp point to the next and this will then correct for the pitch error in my leadscrew. I agree that the laser thing is the ultimate solution to a problem like this but since I can measure easily to .0001" on the machine, I am confident that I can correct the error to at least .0002". If you know of another parameter in the control that can scale the movement of the X axis by a certain factor, I would be just as happy to go that route but I am unable to find this parameter.

    Thanks for your input.
    Glenn

  6. #6
    Join Date
    Nov 2005
    Posts
    274
    Quote Originally Posted by metronorth View Post
    bluesman;

    The research that I have done so far seems to indicate that the pitch error comp value is applied proportionally to the distance that the axis moves from one point to the next. Since I have a very linear error, which I have measured carefully throughout the length of the stroke, I am hoping that I can set a minimum point at the extreme X- end of the axis travel, a reference point and a Maximum point at the extreme X+ end of the axis travel. If my understanding is correct, the error correction amount will be added in proportionally from one comp point to the next and this will then correct for the pitch error in my lead screw. I agree that the laser thing is the ultimate solution to a problem like this but since I can measure easily to .0001" on the machine, I am confident that I can correct the error to at least .0002". If you know of another parameter in the control that can scale the movement of the X axis by a certain factor, I would be just as happy to go that route but I am unable to find this parameter.

    Thanks for your input.
    Glenn

    Well I never did do any research but I worked for a Mori distributor for 4 years and when we "shot" in pitch error comps we always did it just like I told you.
    Your pitch error comps on a 21I should start around 2000 or so and will say "Pitch Error Comp" if you can not find them then you do not have the option. Now you can research the option to turn them on or you could just ask some one in here who knows, (Like the Bluesman) and he can tell you how to turn them on.
    Just for the record pitch error comps are usually scaled in millionths or sometimes pulses (That gets real tricky). So make sure you do enough research to know what and how far you are moving.

    Bluesman

  7. #7
    Join Date
    Nov 2005
    Posts
    274

    Pitch Instructions

    (nuts)Normally I would not exstend this much help to such a "Richard Head" but I really want to see how you come out. Here is the attatchment with all the info you need. I was wrong about the partrametrs they start @3600 or so for the 21I. Once you get it all set up you can have fun.

    Bluesman

  8. #8
    Join Date
    Nov 2005
    Posts
    274
    Quote Originally Posted by Bluesman View Post
    (nuts)Normally I would not exstend this much help to such a "Richard Head" but I really want to see how you come out. Here is the attatchment with all the info you need. I was wrong about the partrametrs they start @3600 or so for the 21I. Once you get it all set up you can have fun.

    Bluesman
    Here
    Attached Files Attached Files

  9. #9
    Join Date
    Oct 2007
    Posts
    5
    Bluesman;

    Thanks for all the help, the info you sent is exactly what I was looking for. As per one of your earlier replies, the option is turned on (now) and the pitch comp tables are visible in the machine. I will work on this and let you know how it turns out. By the way, who is "Richard Head" or am I missing some sort of inside joke?

    Glenn

  10. #10
    Join Date
    Nov 2005
    Posts
    274
    Quote Originally Posted by metronorth View Post
    Bluesman;

    Thanks for all the help, the info you sent is exactly what I was looking for. As per one of your earlier replies, the option is turned on (now) and the pitch comp tables are visible in the machine. I will work on this and let you know how it turns out. By the way, who is "Richard Head" or am I missing some sort of inside joke?

    Glenn
    Well Glenn when you come into a Forum full of folks that are here souly for the purpose of gaining and sharing knowledge, And you ask a question and you are given a very honest and accurate answer. you reply "The research that I have done so far seems" That is a tad condesending and a bit on the rude side. Dick is short for "Richard" this Forum will not allow me to directly call you by the your given name. We are supposed to keep it cordial in here

    Bluesman

  11. #11
    Join Date
    Oct 2007
    Posts
    5
    Ah, now I get it. My tone obviously didn't communicate well through written text. What I meant by "seems" is that I don't know and my understanding of what I am trying to learn (research) is possibly incorrect. I may not be able to do what I am trying but I have to try at least once and I'm here because I need the knowledge, not to offend. Again, thanks and I will keep you posted on the results.

    Glenn, aka Richard

  12. #12
    Join Date
    Nov 2007
    Posts
    1

    Smile pitch error compensation

    Quote Originally Posted by Bluesman View Post
    Here
    Hi Bluesman
    I have same issues on understanding how to set compensation values in controller,
    I can see all perameters but do not fully understand how to apply them
    i am sure your attachment would be helpfull but link is not valid
    can you please re-attach
    thank you in advance
    Norm

  13. #13
    Join Date
    Jan 2007
    Posts
    13
    Hi there,

    Can go visit this website www.cdmeasure.com or email this guy (William) at
    [email protected]

    He can provides helpful information about how to setup the parameter correctly.

    Rgds
    Kelvin

  14. #14
    Join Date
    Jul 2010
    Posts
    0

    fanuc O-m series control

    I am also suffering from same problem, I am not able to see pitch error compensation parameter no. 1000-1127 &2000-2127.on fanuc O-T series
    Plz any one can help me??

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