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i need help with a big part with iterative

pcdmisstudent
Hey guys
so i have this big part, that the datums are defined by 3 datums points (three holes with sample hits that i did iterative with). I then constructed three theorietical planes (alignment planes) and defined those as ABC. Then i measured all the different features on the parted and called them out using FCF position.
the program works well, but some of my results gets weirdly high.
Ill upload pics with the datum targets (see black circles)
Attached Files
  • in reply to pcdmisstudent
    Your datums could be the culprits here.

  • I changed the correct axis for the plane evaluation now. Nominal is 37, measured is 38 for one plane, 38.5 for the other plane. so it makes sense that the TP dev is 2 and 3mm.
    but i have a hard time believing its acctually that far off from the part. since when we measure the height of the plane manually its spot on

    It has to be the datums that are spooking. ill post a snippet soon 

  • CNCLÄGE/CNC
KOMMENTAR/OPERATÖR,NEJ,HELSKÄRM=NEJ,FORTSÄTT AUTOMATISKT=NEJ,
cnc startas!

L1 =MÄRKE/

CIR_A2 =ELEM/KONTAKT/CIRKEL/STANDARDVÄRDE,REKTANGULÄRA,INRE,GAUSS
TEOR/<135.25,0,0>,<1,0,0>,25
MÄTT/<136.091,-0.196,-0.14>,<0.999958,-0.0085354,-0.0033285>,25.121
MÅL/<135.25,0,0>,<1,0,0>
STARTVINKEL=0,SLUTVINKEL=360
VINKELVEKT=<0,0,-1>
RIKTNING=CCW
VISA ELEMENTPARAMETRAR=NEJ
VISA KONTAKTPARAMETRAR=JA
ANTPKTR=7,DJUP=2,STIGNING=0
STICKPROVSMETOD=STÖDPUNKTER
STÖDPUNKTER=4,DISTANS=4
KRINGGÅENDE RÖRELSE=BÅDA,AVSTÅND=10
SÖK ELEMENT=INAKTIV,VID_FEL=NEJ,LÄS POS=NEJ
VISA MÄTPUNKTER=NEJ

CIR_A3 =ELEM/KONTAKT/CIRKEL/STANDARDVÄRDE,REKTANGULÄRA,INRE,GAUSS
TEOR/<135.25,22,200>,<1,0,0>,25
MÄTT/<136.185,21.793,199.887>,<0.9999188,-0.0070527,0.0106123>,25.125
MÅL/<135.25,22,200>,<1,0,0>
STARTVINKEL=0,SLUTVINKEL=360
VINKELVEKT=<0,0,-1>
RIKTNING=CCW
VISA ELEMENTPARAMETRAR=NEJ
VISA KONTAKTPARAMETRAR=JA
ANTPKTR=7,DJUP=2,STIGNING=0
STICKPROVSMETOD=STÖDPUNKTER
STÖDPUNKTER=4,DISTANS=4
KRINGGÅENDE RÖRELSE=BÅDA,AVSTÅND=10
SÖK ELEMENT=INAKTIV,VID_FEL=NEJ,LÄS POS=NEJ
VISA MÄTPUNKTER=NEJ

MÄTSPETS/T2A0B0, SKAFTIJK=-1, 0, 0, VINKEL=0

CIR_A1 =ELEM/KONTAKT/CIRKEL/STANDARDVÄRDE,REKTANGULÄRA,INRE,GAUSS
TEOR/<-135.25,0,0>,<-1,0,0>,25
MÄTT/<-134.666,0.425,0.533>,<-0.9999322,0.0116092,0.0008601>,25.121
MÅL/<-135.25,0,0>,<-1,0,0>
STARTVINKEL=0,SLUTVINKEL=360
VINKELVEKT=<0,0,1>
RIKTNING=CCW
VISA ELEMENTPARAMETRAR=NEJ
VISA KONTAKTPARAMETRAR=JA
ANTPKTR=7,DJUP=2,STIGNING=0
STICKPROVSMETOD=STÖDPUNKTER
STÖDPUNKTER=4,DISTANS=4
KRINGGÅENDE RÖRELSE=BÅDA,AVSTÅND=10
SÖK ELEMENT=INAKTIV,VID_FEL=NEJ,LÄS POS=NEJ
VISA MÄTPUNKTER=NEJ

A2 =UPPRIKTNING/START,ÅTERKALLA:A1,LISTA=JA
UPPRIKTNING/ITERERA
MÅLPKT-RADIE=0.5,STARTMÄRKE=L1,FIXTURTOLERANS=0.05,FELLÄG E=
MÄT ALLA ELEM.=ALLTID,MAX_ANT_ITERATIONER=3,PRIMÄRAXEL=Y-AXEL,SEKUNDÄRAXEL=Z-AXEL,NOLLPUNKTSAXEL=X-AXEL
PRIMÄR=CIR_A1,CIR_A2,CIR_A3,,
SEKUNDÄR=CIR_A1,CIR_A2,,
NOLLPUNKT=CIR_A1,CIR_A2,,
UPPRIKTNING/SLUT

PLAN1 =ELEMENT/PLAN,REKTANGULÄRA,TRIANGEL,NEJ
TEOR/<0,0,0>,<0,1,0>
MÄTT/<0,0,0>,<0,1,0>
KONSTR/PLAN,UPPR,YPLUS
PLAN2 =ELEMENT/PLAN,REKTANGULÄRA,TRIANGEL,NEJ
TEOR/<0,0,0>,<0,0,1>
MÄTT/<0,0,0>,<0,0,1>
KONSTR/PLAN,UPPR,ZPLUS
PLAN3 =ELEMENT/PLAN,REKTANGULÄRA,TRIANGEL,NEJ
TEOR/<0,0,0>,<1,0,0>
MÄTT/<0,0,0>,<1,0,0>
KONSTR/PLAN,UPPR,XPLUS
REFDEF/A,ELEMENT=PLAN1,,
REFDEF/B,ELEMENT=PLAN2,,
REFDEF/C,ELEMENT=PLAN3,,​

  • notice in my first post that there are 4 holes, where 3 of them (circled ones) are datum targets
    When i call out position of the 2x top holes the one being a datum target gets much better deviation than the one thats not included in the iterative alignment.
    They should have closely the same deviation
    Attached Files 

  • 
A2 =UPPRIKTNING/START,ÅTERKALLA:A1,LISTA=JA
UPPRIKTNING/ITERERA
MÅLPKT-RADIE=0.5,STARTMÄRKE=L1,FIXTURTOLERANS=0.05,FELLÄG E=
MÄT ALLA ELEM.=ALLTID,MAX_ANT_ITERATIONER=3,PRIMÄRAXEL=Y-AXEL,SEKUNDÄRAXEL=Z-AXEL,NOLLPUNKTSAXEL=X-AXEL
PRIMÄR=CIR_A1,CIR_A2,CIR_A3,,
SEKUNDÄR=CIR_A1,CIR_A2,,
NOLLPUNKT=CIR_A1,CIR_A2,,
UPPRIKTNING/****


    The origin in the alignment should only be using one of the circles

  • Ok, but drawing specifices C1 and C2 so i thought i should use them both
    Attached Files
  • in reply to pcdmisstudent
    You need to just use one feature for the origin. If you want to use both then construct a midpoint between the two circles and use that in the alignment. You can't use two features.
  • in reply to pcdmisstudent
    ok i will try the midpoint version and see if it'll help
  • me personally dont get this alignment.
    i mean the part takes up almost the entire CMM volume, its big boy part.
    and for alignment there are just 3 circles with sample hits.
    it seems to me and my noob brain that a bigger feature would be better for this part, because of projection error etc.
    3 tiny small circles for big boy part huh..
  • please
    i just lost my CMM reputation here, everyone thinks im a joke now cos it measures wrong and i dont know what to align to...
    i told my boss im going to ask my friend VPT, he will for sure know...
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