True Position in 3 axis???

Ok, I have read the post regarding this so called argument that my boss and I got into today. He told me that you cannot measure true position in 3 axis, as I told him he was wrong. I know it depends on the way the FCF calls it out, but I tried to explain to him that it is possible to measure TP in 3 axis.
I have seen the formulas, so I know it's possible. I just wish I could get one of you gurus to reply back explaining that it is possible and why. I see the picture but he does not. I do not like to get into pissing matches with upper management, but I have learned a h**ll of alot from you guys, and I know this is possible. So if one of you fine gentleman can back me up on this, I would very much appreciate it. Thank you very much.
Now I am going to get a cold beer.

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lambo over 16 years ago

this is my atempt at a formula for spherical true position

tp=2√ (xdev²+ydev²+zdev²)

it's been a long time since i did any real math

fify

john,
the part is a square block with a counter bore in the middle of it. The drawing is asking position of the "central point " of the cylinder ( meaning center of x,y,z) of the cylinder to datums, a-b-c. A datum in x, b datum in y , and c datum in z from the bottom of the part. Basically it's a point that has been established within the cylinder with basic dimension to all 3 axis noted as datums. It only makes sense to me that if that centroid point has been given basic dimensions from 3 axis that are labled datums a-b-c-, that you should be able to calculate it as all 3.

Is the cylinder normal to the datum axes? If it is at an angle/compound angle then it's not a 3D TP even though it's a 3D basic dim. called out.

PC-DMIS does not support this type of TP, you must report XYZ and IJK direction of cosine for that cylinder separately, for TP you must rotate and translate to theoretical position to that cylinder but measure it as a circle at both ends. With same set of basic dim's also apply to the adjacent surface of that cylinder to control the elevation and angulations of that surface, there should be profile called out for that surface.
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lambo over 16 years ago

this is my atempt at a formula for spherical true position

tp=2√ (xdev²+ydev²+zdev²)

it's been a long time since i did any real math

fify

john,
the part is a square block with a counter bore in the middle of it. The drawing is asking position of the "central point " of the cylinder ( meaning center of x,y,z) of the cylinder to datums, a-b-c. A datum in x, b datum in y , and c datum in z from the bottom of the part. Basically it's a point that has been established within the cylinder with basic dimension to all 3 axis noted as datums. It only makes sense to me that if that centroid point has been given basic dimensions from 3 axis that are labled datums a-b-c-, that you should be able to calculate it as all 3.

Is the cylinder normal to the datum axes? If it is at an angle/compound angle then it's not a 3D TP even though it's a 3D basic dim. called out.

PC-DMIS does not support this type of TP, you must report XYZ and IJK direction of cosine for that cylinder separately, for TP you must rotate and translate to theoretical position to that cylinder but measure it as a circle at both ends. With same set of basic dim's also apply to the adjacent surface of that cylinder to control the elevation and angulations of that surface, there should be profile called out for that surface.
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