Help to fix an inaccurate program

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  • Help to fix an inaccurate program

    First: quick background, companies old CMM programmer/operator left the company. I have taken his place. This particular part has been a problem for a while. I have found that if I rotate the part i can affect the results I get in the program as much as .0050".

    now for the area I think is the problem, he makes an alignment and levels on a point, has anyone ever done this?

    LEVEL =ALIGNMENT/START,RECALL:STARTUP, LIST= YES
    ALIGNMENT/LEVEL,ZPLUS,CYLINDER1
    ALIGNMENT/TRANS,XAXIS,CYLINDER1
    ALIGNMENT/TRANS,YAXIS,CYLINDER1
    ALIGNMENT/TRANS,ZAXIS,6_OCLOCK
    ALIGNMENT/END
    CLEARP/ZPLUS,1,ZPLUS,0
    MOVE/CLEARPLANE
    POINT1 =AUTO/VECTOR POINT,SHOWALLPARAMS = YES
    THEO/0,-0.55,0,0,0,1
    ACTL/0.0002,-0.5498,-0.0002,0,0,1
    TARG/0,-0.55,0,0,0,1
    THEO_THICKNESS = 0,RECT,SNAP = NO,$
    AUTO MOVE = NO,DISTANCE = 0.25
    PRE_ALIGN =ALIGNMENT/START,RECALL:LEVEL, LIST= YES
    ALIGNMENT/TRANS,ZAXIS,POINT1
    ALIGNMENT/END
    MOVESPEED/ 100
    MOVE/CLEARPLANE
    DAT_A_TUBE =AUTO/CYLINDER,SHOWALLPARAMS = YES,SHOWHITS = NO
    THEO/0,0,0,0,0,1,1.2,-3
    ACTL/0,0,0,-0.0000182,-0.0000035,1,1.2507,-3
    TARG/0,0,0,0,0,1
    THEO_THICKNESS = 0,RECT,OUT,CIRCULAR,LEAST_SQR,ONERROR = NO,$
    AUTO MOVE = NO,DISTANCE = 0.25,RMEAS = None,None,None,$
    READ POS = NO,FIND HOLE = NO,REMEASURE = NO,USE THEO = NO,$
    NUMHITS = 12,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = -0.25,PITCH = 0,$
    START ANG = 0,END ANG = 360,DEPTH = 0.2,$
    ANGLE VEC = 1,0.0000003,0
    DCC_LEVEL =ALIGNMENT/START,RECALL:PRE_ALIGN, LIST= YES
    ALIGNMENT/LEVEL,ZPLUS,POINT1
    ALIGNMENT/TRANS,XAXIS,DAT_A_TUBE
    ALIGNMENT/TRANS,YAXIS,DAT_A_TUBE
    ALIGNMENT/TRANS,ZAXIS,POINT1
    ALIGNMENT/END

    I am not sure, but I beleive the last alignment is the cause of my variation (or is there something I can learn from this)?

    thank you in advance for your help

    oh almost forgot....

    Sheffield Endevor
    running PCDMIS 3.7 mr3

  • #2
    Yeah you have the right idea.... don't level to a point. Change that alignment to level to a plane and I'm sure you'll find a reduction in your measurement variance.

    Comment


    • #3
      Use Datum A to level to.

      Comment


      • #4
        the measrued cylinder is Datum A

        Comment


        • #5
          Originally posted by pawski4 View Post
          the measrued cylinder is Datum A
          Need more information on your datum A cylinder. How many hits? How many levels? How long is datum A cylinder?
          B & S XCEL 7-10-7
          Sharpe32 Controller
          PH10MQ & ACR1 Toolchanger
          TP20 & TP2 Probes
          Pcdmis CAD++ 3.7mr3, 4.3mr1, 2009mr1, 2010mr1
          Datapage RT 3.33
          sigpic

          Comment


          • #6
            DAT_A_TUBE =AUTO/CYLINDER,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/0,0,0,0,0,1,1.2,-3
            ACTL/0,0,0,-0.0000182,-0.0000035,1,1.2507,-3
            TARG/0,0,0,0,0,1
            THEO_THICKNESS = 0,RECT,OUT,CIRCULAR,LEAST_SQR,ONERROR = NO,$
            AUTO MOVE = NO,DISTANCE = 0.25,RMEAS = None,None,None,$
            READ POS = NO,FIND HOLE = NO,REMEASURE = NO,USE THEO = NO,$
            NUMHITS = 12,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = -0.25,PITCH = 0,$
            START ANG = 0,END ANG = 360,DEPTH = 0.2,$
            ANGLE VEC = 1,0.0000003,0

            NUMHITS=12
            NUMROWS=2
            PROGRAMMED HEIGHT IS -3"

            Comment


            • #7
              Originally posted by Chally72 View Post
              Yeah you have the right idea.... don't level to a point. Change that alignment to level to a plane and I'm sure you'll find a reduction in your measurement variance.
              +1

              I also would advise using at least three rows in cylinders, whether auto or created. When using two rows, the software sometimes applies a different vector than what is intended. With twelve points in each row it may be less likely, but it's a best-practice I always use.
              sigpic

              Comment


              • #8
                Originally posted by pawski4 View Post
                DAT_A_TUBE =AUTO/CYLINDER,SHOWALLPARAMS = YES,SHOWHITS = NO
                THEO/0,0,0,0,0,1,1.2,-3
                ACTL/0,0,0,-0.0000182,-0.0000035,1,1.2507,-3
                TARG/0,0,0,0,0,1
                THEO_THICKNESS = 0,RECT,OUT,CIRCULAR,LEAST_SQR,ONERROR = NO,$
                AUTO MOVE = NO,DISTANCE = 0.25,RMEAS = None,None,None,$
                READ POS = NO,FIND HOLE = NO,REMEASURE = NO,USE THEO = NO,$
                NUMHITS = 12,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = -0.25,PITCH = 0,$
                START ANG = 0,END ANG = 360,DEPTH = 0.2,$
                ANGLE VEC = 1,0.0000003,0

                NUMHITS=12
                NUMROWS=2
                PROGRAMMED HEIGHT IS -3"
                For starters I would increase the number of rows to at least 3 because this feature is your primary datum A used in your alignment and the more hits the better. Do you have room to take sample hits to help define auto/cylinder?

                CYL_1 =FEAT/CONTACT/CYLINDER,CARTESIAN,IN,LEAST_SQR
                THEO/<8.124,0,-55.13>,<-1,0,0>,39.998,13.602
                ACTL/<8.124,0,-55.13>,<-1,0,0>,39.998,13.602
                TARG/<8.124,0,-55.13>,<-1,0,0>
                START ANG=0,END ANG=360
                ANGLE VEC=<0,0,1>
                DIRECTION=CCW
                SHOW FEATURE PARAMETERS=NO
                SHOW CONTACT PARAMETERS=YES
                NUMHITS=8,NUMLEVELS=3,DEPTH=1,END OFFSET=1,PITCH=0
                SAMPLE HITS=3,SPACER=2
                AVOIDANCE MOVE=BOTH,DISTANCE=2.5
                FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
                SHOW HITS=NO
                B & S XCEL 7-10-7
                Sharpe32 Controller
                PH10MQ & ACR1 Toolchanger
                TP20 & TP2 Probes
                Pcdmis CAD++ 3.7mr3, 4.3mr1, 2009mr1, 2010mr1
                Datapage RT 3.33
                sigpic

                Comment


                • #9
                  DAT_A_TUBE =AUTO/CYLINDER,SHOWALLPARAMS = YES,SHOWHITS = NO
                  THEO/0,0,0,0,0,1,1.2,-3
                  ACTL/0,0,0,0.0000076,-0.0000139,1,1.2506,-3
                  TARG/0,0,0,0,0,1
                  THEO_THICKNESS = 0,RECT,OUT,CIRCULAR,LEAST_SQR,ONERROR = NO,$
                  AUTO MOVE = NO,DISTANCE = 0.25,RMEAS = None,None,None,$
                  READ POS = NO,FIND HOLE = NO,REMEASURE = NO,USE THEO = NO,$
                  NUMHITS = 12,NUMROWS = 3,INIT = 0,PERM = 0,SPACER = -0.25,PITCH = 0,$
                  START ANG = 0,END ANG = 360,DEPTH = 0.2,$
                  ANGLE VEC = 1,0,0
                  DCC_LEVEL =ALIGNMENT/START,RECALL:PRE_ALIGN, LIST= YES
                  ALIGNMENT/LEVEL,ZPLUS,DAT_A_TUBE
                  ALIGNMENT/TRANS,XAXIS,DAT_A_TUBE
                  ALIGNMENT/TRANS,YAXIS,DAT_A_TUBE
                  ALIGNMENT/TRANS,ZAXIS,POINT1
                  ALIGNMENT/END

                  ok I made 3 rows for the cylinder, and I changed the alignment level to Dat A. will this work correctly?

                  Comment


                  • #10
                    and about your sample hits question kpayne, I do not know what those are or how to use them. I have looked in the help files for pcdmis and do not see any information on them, also I have no idea how to tell pcdmis to use them, when I look at the auto cylinder dialogue box I see nothing about sample hits.

                    Comment


                    • #11
                      IF -A- is the primary datum in the fcf, then level to -A-.

                      Without seeing the part or a sketch, really can't say what you need.

                      POINT1 in your code has vectors of 0,0,1 , so you might be able to level to that, but I probably wouldn't do that.

                      B&S CHAMELEON/PCDMIS CAD++ V2011

                      There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

                      sigpic

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                      • #12
                        foryourreview.pdf

                        I got permission from the VP of engineering to post this much of print. Hope it help those of you trying to assist me

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                        • #13
                          I don't know which standard that drawing is made to, but seeing as the datum A connects to the surface of the cylinder (not the centerline) in ISO world that means that the generatrixes of the cylinder (not the centerline) defines datum A.
                          PC-DMIS CAD++ 2o19 R1 SP11

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                          • #14
                            so can I align the part to the generatrixes? I need to check if the grooves are concentric with Datum A within .002"

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                            • #15
                              Concentricity is reported the same as location by PC-DMIS.

                              B&S CHAMELEON/PCDMIS CAD++ V2011

                              There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

                              sigpic

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