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GEOTOL help

browningdmis
management had me run a test. I taped a 2,4,6 block to the table. took the top plane, x+ and y- and created my alignment. I then called them datum a top b x and c y. I measured 2 holes on each side and did a position in geotol. I used the same measured data in legacy and got a .010 difference. How can this be?

What management is saying is the position formula. 2 x (dx^2 + dy^2)^1/2 when you figure it manually using the measured values matches legacy perfectly but it is not matching in GEOTOL.

I understand this is rough and dirty test but I can not explain why parts we measure good with second methods and legacy are good. GEOTOL (which our customer uses and requires) is failing the part. I have asked Hexagon this question and keep being told that GEOTOL is correct to the standard. Which is great but the standard use the 2 x (dx^2 + dy^2)^1/2 formula and is passing this but failing in GEOTOL.

I am not bashing PCD Hexagon or anything but I can not explain it to management.

What am I missing??​
  • in reply to Mike Ruff
    But what does the alignment have to do with it. The DRF is correct in both. Is it calculating the alignment and the DRF? The FCF calls for ABC and the DRF is ABC not sure why the alignment matters once it has established the part location.

    If the DRF and the alignment are both used in the calculation that explains why my stuff is off but I do not understand the reason why it would use both. If you set you datum a plane as datum a it should not matter where your alignment is as datum a is datum a.
  • in reply to Mike Ruff
    Mike

    this code was also not comparing legacy to GEOTOL. This is all in geotol. Sorry I should have separated the 2 parts.
  • in reply to Mike Ruff
    Like Ruff said, your alignments are not the same. So you can't compare the 2. For instance, you are leveling on the b datum plane in your legacy and leveling on the A datum plane in Geotol. And "no", the alignments of legacy and geotol are not used in conjunction with each other. It either uses one or the other depending on how you report it out. Try matching your datums schemes to each other in the same order.
  • in reply to Mike Ruff
    mike and mark I am not understand what your talking about. I have 1 man alignment and 1 dcc alignment. I am not using legacy at all. This is all geotol. my datums are top plane b front plane a and side c

    MAN_ALIG =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
    ALIGNMENT/LEVEL,ZPLUS,MAN_DATUM_B
    ALIGNMENT/TRANS,ZAXIS,MAN_DATUM_B
    ALIGNMENT/ROTATE,YMINUS,TO,MAN_DATUM_A,ABOUT,ZPLUS
    ALIGNMENT/TRANS,YAXIS,MAN_DATUM_A
    ALIGNMENT/TRANS,XAXIS,MAN_C
    ALIGNMENT/END
    MODE/DCC
    DCC_DATUM_B=FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,TRIANGLE,LEAST_SQR
    THEO/<1.6683,0.8577,0>,<0,0,1>
    ACTL/<1.6683,0.8577,0>,<0,0,1>
    TARG/<1.6683,0.8577,0>,<0,0,1>
    ANGLE VEC=<1,0,0>,SQUARE
    SHOW FEATURE PARAMETERS=NO
    SHOW CONTACT PARAMETERS=YES
    NUMHITS=2,NUMROWS=2
    SPACER=0.6
    AVOIDANCE MOVE=BOTH,DISTANCE BEFORE=0.3937,DISTANCE AFTER=0.3937,DIRECTION=ALONG FEATURE VECTOR
    SHOW HITS=NO
    DCC_DATUM_A=FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,TRIANGLE,LEAST_SQR
    THEO/<1.7627,0,-0.8071>,<0,-1,0>
    ACTL/<1.7627,0,-0.8071>,<0,-1,0>
    TARG/<1.7627,0,-0.8071>,<0,-1,0>
    ANGLE VEC=<1,0,0>,SQUARE
    SHOW FEATURE PARAMETERS=NO
    SHOW CONTACT PARAMETERS=YES
    NUMHITS=2,NUMROWS=2
    SPACER=0
    AVOIDANCE MOVE=BOTH,DISTANCE BEFORE=0.3937,DISTANCE AFTER=0.3937,DIRECTION=ALONG FEATURE VECTOR
    SHOW HITS=NO
    DCC_DATUM_C=FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,TRIANGLE,LEAST_SQR
    THEO/<0,2.7109,-0.5737>,<-1,0,0>
    ACTL/<0,2.7109,-0.5737>,<-1,0,0>
    TARG/<0,2.7109,-0.5737>,<-1,0,0>
    ANGLE VEC=<0,0,1>,SQUARE
    SHOW FEATURE PARAMETERS=NO
    SHOW CONTACT PARAMETERS=YES
    NUMHITS=2,NUMROWS=2
    SPACER=0
    AVOIDANCE MOVE=BOTH,DISTANCE BEFORE=0.3937,DISTANCE AFTER=0.3937,DIRECTION=ALONG FEATURE VECTOR
    SHOW HITS=NO
    DCC_DATUM_C=ALIGNMENT/START,RECALL:STARTUP,LIST=YES
    ALIGNMENT/LEVEL,ZPLUS,DCC_DATUM_B
    ALIGNMENT/TRANS,ZAXIS,DCC_DATUM_B
    ALIGNMENT/ROTATE,YMINUS,TO,DCC_DATUM_A,ABOUT,ZPLUS
    ALIGNMENT/TRANS,YAXIS,DCC_DATUM_A
    ALIGNMENT/TRANS,XAXIS,DCC_DATUM_C
    ALIGNMENT/END
  • My alignment and DRF are exactly the same????
  • in reply to JacobCheverie
    If you have small amount of points, least square is preferred. If you have many, many points (scan covering alot of area) use STANDARD.


  • Can you send me the routine that you are questioning - the one that has the measured data and the comparison between legacy and the geometric tolerance command?
    You can use this link to upload it to our secure file share site: https://sendit.hexagon.com/filedrop/~5diqk0

    There are many, many reasons why you may not be able to get the numbers to match but once I have the routine, I will be able to explain what is going on.
  • in reply to Neil Challinor


    I received your program but none of the features have measured data (everything is nominal) so it is not much use for investigative / comparison purposes. Is it possible for you to execute it on an actual part, save a copy and then send that to me?
  • in reply to Neil Challinor
    neil

    that is correct. it has not been run yet. I will run it today and send you the data from there. I was more worried about what I am missing that would cause me to have to look at the data more close and then compare to legacy. Up front vs after the run.
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