Relative Measurement

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  • Relative Measurement

    Hi Everyone,

    I am a new user to CMM and pc-dmis program and I have a question which I cannot solve on my own.
    I am trying to establish a relative measurement where I am able to move my part anywhere within my CMM and get the same alignment.
    I know to manually make six points and set an alignment and then execute with DCC mode to execute my program.
    I cannot get it to work...when I move by part to a different location, following the DCC mode it locates the point on the original orientation...I feel like I am making a common mistask not programming correctly. What am I missing or doing wrong?

  • #2
    Have you had any formal instruction on using PC-DMIS?

    Have you had any formal instruction in constraining the 6° of freedom in order to be considered properly aligned?

    Have you made a manual alignment and a DCC alignment to the datum structure as called out on the print?


    these are not questions to make you look un-intelligent, these are questions to get an idea of where to start giving you some directions.

    Please post your program via the copy/paste function. If you do that in conjunction with the # sign found on the toolbar you will make it easier to read your program.

    Welcome to the board!!!
    sigpic

    James Mannes

    Comment


    • #3
      What are you doing (or not doing) to tell the CMM that you have moved the part? You must create another alignment on the new location/orientation.
      sigpic
      Global Advantage 12-22-10
      TESASTAR M SP25 4.3mr2

      Comment


      • #4
        This might help. Posting part of your code would make it easier for us to help. Your program should go something like this:
        1. Manual alignment (this can be a simple 1-2-3 alignment)
        2. DCC alignment (I duplicate my manual alignment)
        3. DCC alignment to datum scheme. (I only do this when I can't align to the Datum scheme manually)
        4. Body of program


        Each time you run the program you need to run the manual alignment.
        There are ways around that, but let's get you going in this first.
        When in doubt, post code. A second set of eyes might see something you missed.
        sigpic

        Comment


        • #5
          My program

          First I would like to say Thanks to does that replied...this is useful information since I have no training in pc-dmis and I am learning this on my own. I will go to training for my job soon.

          Well guys, this is my program...Like i said before this is what i did:
          1) Manual mode and plane, line and point.
          2) Set alignment
          3) DCC mode and then body

          Where did I go wrong?



          STARTUP =ALIGNMENT/START,RECALL:,LIST=YES
          ALIGNMENT/END
          MODE/MANUAL
          PREHIT/ 0.11811
          RETRACT/ 0.11811
          MOVESPEED/ 385
          TOUCHSPEED/ 5
          MANRETRACT/2.54
          FORMAT/TEXT,OPTIONS, ,HEADINGS,SYMBOLS, ;NOM,TOL,MEAS,DEV,OUTTOL, ,
          LOADPROBE/ISO
          COMMENT/OPER,NO,Locate probe to a safe location for tip change
          TIP/T1A45B135, SHANKIJK=-0.5, -0.5, 0.70711, ANGLE=125.26439
          COMMENT/OPER,NO,Victor give instructions for measuring plane
          WORKPLANE/YMINUS
          PRELEVEL =FEAT/PLANE,CARTESIAN,TRIANGLE
          THEO/<0.92625,-23.75225,-0.86479>,<0.0134624,-0.9996065,0.0246081>
          ACTL/<0.926,-23.75233,-0.86544>,<0.013479,-0.9996063,0.0246075>
          MEAS/PLANE,3
          HIT/BASIC,NORMAL,<2.77669,-23.51465,7.77607>,<0.013479,-0.9996063,0.0246075>,<2.77669,-23.51465,7.77607>,USE THEO = YES
          HIT/BASIC,NORMAL,<2.77562,-23.92257,-8.79407>,<0.013479,-0.9996063,0.0246075>,<2.77562,-23.92257,-8.79407>,USE THEO = YES
          HIT/BASIC,NORMAL,<-2.77431,-23.81978,-1.57831>,<0.013479,-0.9996063,0.0246075>,<-2.77431,-23.81978,-1.57831>,USE THEO = YES
          ENDMEAS/
          THEO/<-3.34974,-22.90473,-0.31752>,<-0.0336016,-0.9994353,0>
          ACTL/<-3.34963,-23.18037,7.50001>,<-0.0012165,0,-0.9999993>
          MEAS/LINE,2,WORKPLANE
          HIT/BASIC,NORMAL,<-3.34969,-22.90143,7.50013>,<-0.999429,0.0337884,0>,<-3.34963,-22.8981,7.50001>,USE THEO = YES
          HIT/BASIC,NORMAL,<-3.36871,-23.46597,-8.13463>,<-0.999429,0.0337884,0>,<-3.36865,-23.46264,-8.13475>,USE THEO = YES
          ENDMEAS/
          COMMENT/OPER,NO,Victor give instructions for measuring point
          PRE-Z =FEAT/POINT,CARTESIAN
          THEO/<-1.2871,-22.9432,8.8795>,<0,0,1>
          ACTL/<-1.2871,-22.9432,8.8795>,<0,0,1>
          MEAS/POINT,1
          HIT/BASIC,NORMAL,<-1.2871,-22.9432,8.8795>,<0,0,1>,<-1.2871,-22.9432,8.8795>,USE THEO = YES
          ENDMEAS/
          SETUP =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
          ALIGNMENT/LEVEL,YMINUS,PRELEVEL
          ALIGNMENT/TRANS,YAXIS,PRELEVEL
          ALIGNMENT/ROTATE,ZPLUS,TO,PREROTATION,ABOUT,YMINUS
          ALIGNMENT/TRANS,XAXIS,PREROTATION
          ALIGNMENT/TRANS,ZAXIS,PRE-Z
          ALIGNMENT/END
          COMMENT/OPER,NO,locate probe to safe location for tip change
          TIP/T1A90B-180, SHANKIJK=-0.00431, -0.99969, -0.02453, ANGLE=-179.91642
          COMMENT/OPER,NO,locate probe to x=2.5 y=10 z=8
          MODE/DCC
          MOVE/POINT,NORMAL,<2.75708,-6.28499,7.03966>
          MOVE/POINT,NORMAL,<5.8343,-1.48807,-3.12633>
          MOVE/POINT,NORMAL,<5.83429,-1.48806,-3.12633>
          CIR1 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR
          THEO/<5.93883,0.31584,-3.13044>,<0,-1,0>,0.86351
          ACTL/<-5.73636,-3.0837,3.21892>,<0.0096701,-0.9999532,-0.0000022>,0.86096
          MEAS/CIRCLE,4,WORKPLANE
          HIT/BASIC,NORMAL,<5.84428,0.3,-2.71481>,<0.2218289,0,-0.9750856>,<-5.64143,-3.08278,2.80187>,USE THEO = YES
          MOVE/CIRCULAR
          HIT/BASIC,NORMAL,<6.3716,0.3,-3.16727>,<-0.997119,0,0.0758532>,<-6.16835,-3.08788,3.25553>,USE THEO = YES
          MOVE/CIRCULAR
          HIT/BASIC,NORMAL,<5.96379,0.3,-3.55762>,<-0.0762403,0,0.9970895>,<-5.75782,-3.08391,3.64491>,USE THEO = YES
          MOVE/CIRCULAR
          HIT/BASIC,NORMAL,<5.52346,0.3,-3.25554>,<0.948468,0,0.3168729>,<-5.31899,-3.07966,3.33823>,USE THEO = YES
          MOVE/POINT,NORMAL,<5.9468,0.31777,-3.24019>
          ENDMEAS/
          MOVE/POINT,NORMAL,<5.93603,-2.15529,-3.30092>
          MOVE/POINT,NORMAL,<1.11315,-0.42191,-3.00701>

          Comment


          • #6
            Your alignment appears to call out features that do not exist in your program.
            I couldn't find the feature name PREROTATION.
            That could be a cause of this problem.
            When in doubt, post code. A second set of eyes might see something you missed.
            sigpic

            Comment


            • #7
              vhans,

              Where are you at in Houston? John is correct. Your program seems to have a partial feature or two in it and you are missing a user comment about the line.


              PRELEVEL =FEAT/PLANE,CARTESIAN,TRIANGLE
              THEO/<0.92625,-23.75225,-0.86479>,<0.0134624,-0.9996065,0.0246081>
              ACTL/<0.926,-23.75233,-0.86544>,<0.013479,-0.9996063,0.0246075>
              MEAS/PLANE,3
              HIT/BASIC,NORMAL,<2.77669,-23.51465,7.77607>,<0.013479,-0.9996063,0.0246075>,<2.77669,-23.51465,7.77607>,USE THEO = YES
              HIT/BASIC,NORMAL,<2.77562,-23.92257,-8.79407>,<0.013479,-0.9996063,0.0246075>,<2.77562,-23.92257,-8.79407>,USE THEO = YES
              HIT/BASIC,NORMAL,<-2.77431,-23.81978,-1.57831>,<0.013479,-0.9996063,0.0246075>,<-2.77431,-23.81978,-1.57831>,USE THEO = YES
              ENDMEAS/
              THEO/<-3.34974,-22.90473,-0.31752>,<-0.0336016,-0.9994353,0>
              ACTL/<-3.34963,-23.18037,7.50001>,<-0.0012165,0,-0.9999993>
              MEAS/LINE,2,WORKPLANE
              HIT/BASIC,NORMAL,<-3.34969,-22.90143,7.50013>,<-0.999429,0.0337884,0>,<-3.34963,-22.8981,7.50001>,USE THEO = YES
              HIT/BASIC,NORMAL,<-3.36871,-23.46597,-8.13463>,<-0.999429,0.0337884,0>,<-3.36865,-23.46264,-8.13475>,USE THEO = YES
              ENDMEAS/

              COMMENT/OPER,NO,Victor give instructions for measuring point
              PRE-Z =FEAT/POINT,CARTESIAN
              THEO/<-1.2871,-22.9432,8.8795>,<0,0,1>
              ACTL/<-1.2871,-22.9432,8.8795>,<0,0,1>
              MEAS/POINT,1
              HIT/BASIC,NORMAL,<-1.2871,-22.9432,8.8795>,<0,0,1>,<-1.2871,-22.9432,8.8795>,USE THEO = YES
              ENDMEAS/
              SETUP =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
              ALIGNMENT/LEVEL,YMINUS,PRELEVEL
              ALIGNMENT/TRANS,YAXIS,PRELEVEL
              ALIGNMENT/ROTATE,ZPLUS,TO,PREROTATION,ABOUT,YMINUS
              ALIGNMENT/TRANS,XAXIS,PREROTATION
              ALIGNMENT/TRANS,ZAXIS,PRE-Z
              ALIGNMENT/END


              A sketch or a good description of the part might help. Is this a cylinder?
              If so, it is often better to level to the cylinder rather than the face.
              sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

              Comment


              • #8
                As The Others Have Pointed Out You Have Some Thing Messed Up In Your Program. You Must Of Went Back Into It And Done Some Changes That Messed It Up. Rewrite Your Alignment And When It Asked You To Update Say No. You Should Be Ok. I Hope.
                sigpichttp://npmichaels.com/ (My sons book)
                THANKS (CAD IS ALWAYS MASTER)
                4.3 & 4.2MR2/GLOBAL/PH10MQ/WINDOWS XP

                Comment


                • #9
                  Also, get into the habit of saving frequently. Not the autosave either. When you make a change to an alignment, like pniven suggests, make a backup too. I will have multiple copies of programs when I am modifying things. This way I can go back to my last, best copy.
                  When in doubt, post code. A second set of eyes might see something you missed.
                  sigpic

                  Comment


                  • #10
                    At this point you appear to have some problems with experience which will be solved with training. I would be very careful running the CMM without someone with more experience around you. It is very easy to damage the probe head and ram etc.

                    When I teach a program (I do not have CAD) what I usually do is look at the part and decide how to put the part on the table to get the most bang for the buck. I try to check the part with one setup and have the program work anywhere in the volume without hitting the limit switches. Here is how I start, Some operator comments to say how the part is on the table, Datum -A- plus Z, 1 inch hole Plus X and allign to volume etc,this way whoever runs the part they have some info on how to set it up. 2 years from now you might forget. Then another comment to tell operator to manually put the tip in that 1 inch hole. No more manual intervention after this. (This is what I think you are looking for) another operator comment to take a READPOINT, then translate your zero's in XYZ to this point. Machine now knows where the hole is, check the hole in AUTO and then zero that hole in XYZ again, drive out of the hole and take a hit on the top of the part for Z, now zero Z, then stop rotation on some thing to find the part a little better. You are just finding the part a little better in each step above. By doing this simple step I have never had a part program not find the part. I am keeping it very simple there is alot more to a checking a part, small steps you will get there. Then do a proper allignment per the print callouts.
                    Brian
                    Version 2012

                    sigpic

                    Comment


                    • #11
                      For Wes Cisco:
                      I work in the Galena Park area near I-10 and Market St.

                      what about yourself?

                      Comment


                      • #12
                        Originally posted by vhans View Post
                        For Wes Cisco:
                        I work in the Galena Park area near I-10 and Market St.

                        what about yourself?
                        I work for KNUST, the Galeria area. On Dunvale between Westheimer & Richmond.
                        sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

                        Comment


                        • #13
                          vhans, you are in good hands. I just want to add that it is RARE that I use more than one point to locate a part then let the CMM take over. Move the part and turn the point on for one run.
                          Bill Jarrells
                          A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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