hexagon logo
Register Sign in
  • Replies 21 replies
  • Subscribers 222 subscribers
  • Views 223 views
  • Users 0 members are here
Options
Related

help me measure it, how would u dimension it

pcdmisstudent
hi all
i got a measuring/construction/engineer/noob problem.
i have this small 40 degree, 2 degree conical thing, that is supposed to have a diameter 6.86mm where it is as smallest, and its supposed to be centered in the casted hole(D), and perpendicular to the plane(A)
i dont know how to measure it, since its a very small surface, and its also not cylindrical, its conical with a 2degree angle.
so i have to measure it as a cone. and then construct a circle using cone feature, but the results are very unsure.

the matching part has the exact same feature, except its internal, and it should run free over the tap thingy.
how can i measure it
or how would u else dimension it, so that the matching part fits.
ty all, thanks for ur feedback
Attached Files


  • i cant construct a cone from the circles, it gives me error
  • Are you working under 2011 or 2019 ?
    I'm not at the cmm, so I'm not sur of what you can do :
    If you created fixed rad circles, you know now 2 centers and 2 radii, so you can create 3 generic points/circle, and then construct the cone from them : 
    ASSIGN/V1=CIRC1.XYZ
ASSIGN/V2=CIRC1.R
ASSIGN/V3=CIRC1.NUMHITS
ASSIGN/V4=ROUND(V3/2)
ASSIGN/V5A=UNIT(CIRC1.HIT[1].XYZ-CIRC1.XYZ)
ASSIGN/V5B=UNIT(CIRC1.HIT[V4].XYZ-CIRC1.XYZ)
ASSIGN/V5C=UNIT(CIRC1.HIT[V3].XYZ-CIRC1.XYZ)
PT1 =GENERIC/POINT,DEPENDENT,CARTESIAN,$
NOM/XYZ,<V1.X+V2*V5A.I,V1.Y+V2*V5A.J,V1.Z+V2*V5A.K>,$
MEAS/XYZ,<V1.X+V2*V5A.I,V1.Y+V2*V5A.J,V1.Z+V2*V5A.K,$
NOM/IJK,<V5A.I,V5A.J,V5A.K>,$
MEAS/IJK,<V5A.I,V5A.J,V5A.K>
PT2 =GENERIC/POINT,DEPENDENT,CARTESIAN,$
NOM/XYZ,<V1.X+V2*V5B.I,V1.Y+V2*V5B.J,V1.Z+V2*V5B.K>,$
MEAS/XYZ,<V1.X+V2*V5B.I,V1.Y+V2*V5B.J,V1.Z+V2*V5B.K,$
NOM/IJK,<V5B.I,V5B.J,V5B.K>,$
MEAS/IJK,<V5B.I,V5B.J,V5B.K>
PT3 =GENERIC/POINT,DEPENDENT,CARTESIAN,$
NOM/XYZ,<V1.X+V2*V5C.I,V1.Y+V2*V5C.J,V1.Z+V2*V5C.K>,$
MEAS/XYZ,<V1.X+V2*V5C.I,V1.Y+V2*V5C.J,V1.Z+V2*V5C.K,$
NOM/IJK,<V5C.I,V5C.J,V5C.K>,$
MEAS/IJK,<V5C.I,V5C.J,V5C.K>

    Do the same with circ2...
  • in reply to JEFMAN
    nice jeffman
    i work in 2020 r1.
    will the fixed rad circle be accurate tho? since if i click out a autocircle on cad (which actually is a cone) it gives me a diameter (not 6.86 as in drawing). so the fixedrad circle will have the diameter from the start at the cone, and if i change the depth to 2mm the nominal diameter will stay the same, (But the acctual diameter will get smaller). so it will have wrong nominals
  • how would i compensate for cosine error? (maybe this is question for
    So, if i understand this correctly
    Measure big boy cone, level and orgin to it
    measure two circles on the small arc using fastrad
    compensate for cosine (?)
    construct BF cone using the two circles
    dimension XY for this cone
    orgin to BF cone
    use vector points on small arc
    dimension PRAD

    thanks ninja


    What tip size are you using?


  • @any one else

    this got me curious about how the fixed rad /small arc method acctually works.
    firstly using fixed rad on a surface gets u a more accurate center position since it kinda tries to fit a radius guage to the surface (?)
    and since u have an accurate center position (Which u later orgin in) you can accuratly measure individual points using PRAD (its basically just a distance from center to the vector point)
    but now lets say i key in wrong diameter in the fixedrad circle, lets say 10mm instead of 5mm
    the distance (PRAD) from the center point to the vector point will be much longer than acctual, because pcdmis thinks its 5mm from the vector point instead of 2.5mm
    am i on the right track to understand this? or no?
    (im still just a student)
  • If the center is wrong, then the vector is wrong, so the ball compensation is wrong...



  • @anyone else

    ok but the center wouldnt change if i keyed in the wrong diameter, no? since the centerpoint is static.
    wether i key in10mm or 5mm, the centerpoint would remain the same. So the position of the small arc circle and the big boy hole would be the same even if i used wrong nominal diameter. Its only the distance from center to the vectorpoint that would be wrong.

    true?
  • Using fixed rad fit the diameter to measured points, so if you type the wrong diameter, the center will change, and then vector points will have a wrong compensation...
  • Yes the centre would change. You're taking a fixed radius (so fixed diameter) circle, and best fitting that to your measured points - like you said putting a radius gauge in contact with the part. So if you use the wrong size radius gauge the centre will be off (unlike a radius gauge however, which would always be external to material, the fixed rad circle would have points inside and outside its circumference).


    With a 0.5mm tip diameter and a contact angle of 2° the amount you'd need to reduce the diameter is very small - less than half a micron! (0.0004).
© 2024 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement