Profile of a Surface Scans: Readings WAY too high

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  • Profile of a Surface Scans: Readings WAY too high

    Hey folks,

    So i've gone into PCDMIS because our customer has requested some profile of a surface scans.

    Easy enough, I went in and inserted linear open scans on every part they wanted scanned, ran the program and no crashes. However, there are profile scans on my report that are reading ~0.0005 or less, which is expected, and the other half of my dimensions are showing over 0.0100 and a couple even reached ~0.3000.

    This is an aerospace fine machining facility, i cant imagine that these profiles are truly that high. Any tips from anyone on how to accurately take a profile of a surface?

  • #2
    are your measurements in mm or inches?

    aside from that how are you aligning the part, there must be datums for a profile callout, and your best results are going to be achieved aligning the part to those datums

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    • #3
      Blockay it could be beneficial to post some code. I would post the feature sets along with the alignment itself you are working with.

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      • #4
        Make sure the vectors on the CAD are right..
        you can go into Edit, Graphic display Window, CAD Vectors.. From there drag a box around the entire CAD model and select fix surface vectors.

        I have had bad CAD vectors cause issues with results.
        Time for the Trolls to leave.

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        • #5
          scan options... FIND NOMS, RELEARN, USE SELECTED CAD ONLY
          sigpic
          Originally posted by AndersI
          I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

          Comment


          • #6
            So below you'll find where my datums are, Datum A being the face and Datum B being the circle. It is all aligned directly to the datum.


            COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
            Please Align part with the FWD Side facing the left of the machine.
            PLN1 =FEAT/PLANE,CARTESIAN,TRIANGLE
            THEO/<226.3834,0.7387,-0.4383>,<-1,0,0>
            ACTL/<17.2859,12.3479,-27.8036>,<-0.9999942,-0.0032523,-0.0009943>
            MEAS/PLANE,3
            HIT/BASIC,NORMAL,<226.3834,10.7192,-6.2923>,<-1,0,0>,<17.2654,20.5992,-34.1619>,USE THEO=YES
            HIT/BASIC,NORMAL,<226.3834,1.7,12.184>,<-1,0,0>,<17.2751,11.2042,-13.1608>,USE THEO=YES
            HIT/BASIC,NORMAL,<226.3834,-10.2032,-7.2068>,<-1,0,0>,<17.3173,5.2404,-36.0881>,USE THEO=YES
            ENDMEAS/
            CIR1 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR
            THEO/<229.3914,0,0>,<1,0,0>,7.98
            ACTL/<20.3497,11.6911,-25.8047>,<1,0,0>,7.9871
            MEAS/CIRCLE,3,XPLUS
            HIT/BASIC,NORMAL,<229.4521,3.5503,-1.8209>,<0,-0.8897878,0.4563746>,<20.3495,11.3231,-29.7813>,USE THEO=YES
            HIT/BASIC,NORMAL,<229.3269,0.0642,3.9895>,<0,-0.0160832,-0.9998707>,<20.3503,14.7437,-23.2298>,USE THEO=YES
            HIT/BASIC,NORMAL,<229.3952,-3.2018,-2.3808>,<0,0.8024647,0.5966996>,<20.3494,8.635,-23.2339>,USE THEO=YES
            ENDMEAS/
            A1 =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
            ALIGNMENT/LEVEL,XMINUS,PLN1
            ALIGNMENT/TRANS,XAXIS,PLN1
            ALIGNMENT/TRANS,YAXIS,CIR1
            ALIGNMENT/TRANS,ZAXIS,CIR1
            ALIGNMENT/END
            MODE/DCC
            MOVE/POINT,NORMAL,<-1.3858,0.2881,-0.2481>
            MOVE/POINT,NORMAL,<-0.7185,10.7019,-6.473>
            DATUM A =FEAT/PLANE,CARTESIAN,TRIANGLE
            THEO/<0,0.4642,-0.098>,<-1,0,0>
            ACTL/<0,0.4643,-0.0981>,<-1,-0.0000173,-0.0000125>
            MEAS/PLANE,3
            HIT/BASIC,NORMAL,<0,10.7284,-6.0563>,<-1,0,0>,<-0.0001,10.7285,-6.0563>,USE THEO=YES
            HIT/BASIC,NORMAL,<0,1.0137,12.2717>,<-1,0,0>,<-0.0001,1.0139,12.2717>,USE THEO=YES
            HIT/BASIC,NORMAL,<0,-10.3496,-6.5095>,<-1,0,0>,<0.0003,-10.3495,-6.5097>,USE THEO=YES
            ENDMEAS/
            MOVE/POINT,NORMAL,<-0.2309,-7.4448,-6.7301>
            DATUM B =FEAT/CONTACT/CIRCLE/ADAPTIVE_CIRCLE_SCAN,CARTESIAN,IN,LEAST_SQR
            THEO/<1.016,0,0>,<-1,0,0>,23.08
            ACTL/<1.016,-0.0012,-0.0008>,<-1,0,0>,23.0797
            TARG/<1.016,0,0>,<-1,0,0>
            START ANG=235,END ANG=115
            ANGLE VEC=<0,0,1>
            DIRECTION=CCW
            SHOW FEATURE PARAMETERS=NO
            SHOW CONTACT PARAMETERS=NO
            DATDEF/FEATURE=DATUM A,A
            DATDEF/FEATURE=DATUM B,B

            086scan.PNG

            Also, this is a picture of the scan options:
            086HUBSCAN.PNG


            Douglas, I am in inches, as you can see, the part is aligned to the datums as well.
            ThePudds , see attached
            william Johnson, I tried your method, it looks like all my CAD vectors are indeed pointing the right way
            Matthew D. Hoedeman, I tried that as well, but i didn't see anything too different.

            Comment


            • QS920
              QS920 commented
              Editing a comment
              I don't see any rotation in your alignment above, what are you rotating to?

          • #7
            check it 'old school' and see if individual points are showing the same thing in the same area.
            ALSO, when scanning with a scanning probe, do NOT scan with the tip of the ball, always scan with some portion of the SIDE of the ball. For example, if you wanted to scan the CMM table, don't use a A0B0 tip, use an A45 tip.
            sigpic
            Originally posted by AndersI
            I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

            Comment


            • #8
              Regarding the possibility that the CAD vectors are not pointed outside the model... on the CAD Vectors dialog, if you want to fix the surface vectors of the entire CAD model, you don't need to box select the entire model. When the dialog first comes up, just click on the Fix Vectors button. If no CAD is selected, then the surface vectors of the entire CAD model will be fixed.

              Keep in mind that the fix surface vectors algorithm will not be able to find the correct surface vector in 100% of all cases. An easy way to check if surface vectors are all pointing outside the model is to enable back face culling and/or disable two-sided lighting. For back face culling, surfaces with the vector pointing inside the model will become invisible. For two-sided lighting, the surfaces will become dark. For the surfaces that still have an incorrect vector after running the algorithm, you can manually invert the vector of those surfaces.

              Comment


              • #9
                Originally posted by Matthew D. Hoedeman View Post
                check it 'old school' and see if individual points are showing the same thing in the same area.
                ALSO, when scanning with a scanning probe, do NOT scan with the tip of the ball, always scan with some portion of the SIDE of the ball. For example, if you wanted to scan the CMM table, don't use a A0B0 tip, use an A45 tip.
                This is the first time I've heard this. Why is this the case? Typically most of my scans are A0B0/normal to the probe, and I typically don't have any issues (aside from the profile scans).

                Comment


                • Douglas
                  Douglas commented
                  Editing a comment
                  normal to the probe can also give that stop/go sort of motion more easily... same thing that makes fingernails squeal on the chalkboard can happen to probes

              • #10
                It may depend on your hardware, but the SM25 stuff, not good using the end of the ball (along the shaft) as it will deflect right/left/front/back as it is moving as the machine tried to maintain the correct pressure on the tip. NOT a good analogy, but think about this: If you try pushing a stick along the ground, you'll get a wonky path in the dirt. it will move left, right, you are constantly needing to try to correct the path into a straight line, if you drag it along the ground, you get a straight path without all the work to keep it in a straight line, if ya follow what I mean.
                sigpic
                Originally posted by AndersI
                I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

                Comment


                • VinniUSMC
                  VinniUSMC commented
                  Editing a comment
                  Finally, a use for that stick in the mud.

                • YGOLORTEM
                  YGOLORTEM commented
                  Editing a comment
                  Good analogy

              • #11
                I notice none of your locations are in line with each other, I'm guessing all your "Y's" should be 0? double click the 1 and set each point "0" in the "Y" direction Regenerate the points and try again? also on the Graphics Tab is Thickness "0"

                Capture.JPG



                .

                Capture2.JPG
                (In Memory of my Loving wife, "Ronda" who I lost March 7, 2016. I love you baby.)
                They say "Nobody's Perfect." I must be Nobody.

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                • #12
                  Matthew D. Hoedeman That makes sense, thank you for the info!
                  KIRBSTER269 I went through and corrected those values, same result. Also, the graphics' thickness was set to 0 as well.

                  The customer didn't really specify whether they wanted surface profiles or line profiles, so i think to make this easier on myself for now, I'll just do line profiles.

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                  • #13
                    Do what Matthew D. Hoedeman suggested and check it "old school" (see his post) - maybe that can give you some hints.
                    PC-DMIS CAD++ 2o19 R1 SP11

                    Comment


                    • #14
                      Have you checked the Vectors in your alignment? I use scans on the daily with the same probe. i've noticed that a simple change of a Plane Vector (for example) from .9999986758 (you get it) to 1/-1 would get my scans to follow the path correctly and measure correctly. Giving that 'locked in' look. I also agree with Matt on the scanning A0B0 situation.

                      Scanning Turbine Blades, I've had my share of headaches with scans and profiles. Still might not be perfect, but we making progress!
                      PG

                      PC-DMIS 2010 MR3
                      B&S Global Advantage 7-10-7
                      TesaStar - SP25
                      Houston, TX

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