True Position of threads

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  • True Position of threads

    Hello,
    What are some ways to check true position of threads. (5/8-11 UNC-2B TAP THRU)
    Also, having trouble applying this to the Feature Control Frame Editor. (threads specifically)
    Hopefully someone else knows how to execute this task.

  • #2
    You can use True position locators or apply lead to the measurement.Also remember that probe diameter needs to be adequate.

    http://www.lavezzi.com/TruPos.html
    Time for the Trolls to leave.

    Comment


    • #3
      When checking threads, use the pitch setting in the auto circle feature. That’s the best way to do it if you don’t have locators. Another way is to use a shank probe but when you use a shank probe, make very certain you touch the sphere at A0BO and it’s perfect. If not, you will have a hard time qualifying or may have bad parts.
      Darroll
      2018R2

      Comment


      • #4
        I've gotten this answer from a member here forgot what his name was or i would give credit.

        Create a linear open scan along the bottom of the thread. It doesn't need to be long, just long enough to find the Minor diameter. Create a generic point to the highest point on that scan using "max index". Create an auto cylinder change the pitch to the correct pitch for the thread. Now edit the starting point of the cylinder and use the generic point. This will ensure your probe will always start on the Minor diameter giving you better results.

        Code:
        SCN7       =FEAT/SCAN,LINEAROPEN,NUMBER OF HITS=17,SHOW HITS=NO,SHOWALLPARAMS=YES
                    EXEC MODE=DEFINED, NOMS MODE=NOMINALS,CLEARPLANE=NO,SINGLE POINT=NO,THICKNESS=0
                    FINDNOMS=0.15,SELECTEDONLY=YES,USEBESTFIT=NO,PROBECOMP=YES,AVOIDANCE MOVE=NO,DISTANCE=0,CAD Compensation=NO,4-axis scan=NO
                    DIR1=NULLFILTER,
                    HITTYPE=VECTOR
                    INITVEC=0.0019256,0,0.9999982
                    DIRVEC=0,1,0
                    CUTVEC=-0.9999982,0,0.0019256
                    ENDVEC=0.0019256,0,0.9999982
                    PLANEVEC=0,-1,0
                    POINT1=0,-0.477,-2.698
                    POINT2=0,-0.4228,-2.698
                    MEAS/SCAN
                      BASICSCAN/LINE,NUMBER OF HITS=17,SHOW HITS=NO,SHOWALLPARAMS=YES
                      <0,-0.477,-2.698>,<0,-0.4228,-2.698>,CutVec=-0.9999982,0,0.0019256,DirVec=0,1,0
                      InitVec=0,0,1,EndVec=0,0,1,THICKNESS=0
                      FILTER/NULLFILTER,
                      EXEC MODE=DEFINED
                      BOUNDARY/PLANE,<0,-0.4228,-2.698>,PlaneVec=0,-1,0,Crossings=1
                      HITTYPE/VECTOR
                      NOMS MODE=NOM,0.15
                      ENDSCAN
                    ENDMEAS/
                    ASSIGN/V101=MAXINDEX(SCN7.HIT[1..SCN7.NUMHITS].Z)
        F3         =GENERIC/POINT,DEPENDENT,CARTESIAN,$
                    NOM/XYZ,<SCN7.HIT[V101].X,SCN7.HIT[V101].Y,SCN7.HIT[V101].Z>,$
                    MEAS/XYZ,<SCN7.HIT[V101].X,SCN7.HIT[V101].Y,SCN7.HIT[V101].Z>,$
                    NOM/IJK,<0,0,1>,$
                    MEAS/IJK,<0,0,1>
        CYL10      =FEAT/CONTACT/CYLINDER/ADAPTIVE_CYLINDER_SPIRAL_SCAN,CARTESIAN,IN,LEAST_SQR
                    THEO/<0,F3.Y,-2.63>,<0,-1,0>,0.136,0.1
                    ACTL/<-0.0002,-0.4479,-2.6298>,<0.0011409,-0.9999948,0.0030175>,0.1403,0.1
                    TARG/<0,-0.477,-2.63>,<0,-1,0>
                    START ANG=-90,END ANG=360
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CW
                    SHOW FEATURE PARAMETERS=YES
                      VOID DETECTION=NO
                      REMEASURE=NO,USE THEO=NO
                      SURFACE=THICKNESS_NONE,0
                      MEASURE MODE=NOMINALS
                      RMEAS=NONE,NONE,NONE
                      AUTO WRIST=NO
                      CIRCULAR MOVES=STRAIGHT
                      GRAPHICAL ANALYSIS=NO
                      FEATURE LOCATOR=NO,NO,""
                    SHOW CONTACT PARAMETERS=YES
                      NUMHITS=5,NUMLEVELS=4,DEPTH=0,END OFFSET=0,PITCH=0.0321
                      SAMPLE METHOD=SAMPLE_HITS
                      SAMPLE HITS=0,SPACER=0
                      AVOIDANCE MOVE=NO,DISTANCE=0.3937
                      FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
                    SHOW HITS=NO

        Comment


        • louisd
          louisd commented
          Editing a comment
          you want precision, you need to do the work to get precision.

        • BIGWIG7
          BIGWIG7 commented
          Editing a comment
          *shrugs shoulders*
          depends on the requirement.
          what would be the tightest tolerance required for you to deploy this strategy?

        • Jakep379
          Jakep379 commented
          Editing a comment
          i use this on all threads regardless of Tol just because it is extremely repeatable. However most of our Tol on threads have a .005 thou position. This doesn't require alot of time either once u do a few becomes pretty fast.

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