1) Straight up TP, hypotenuse of the triangle times 2 (hypotenuse = radius, TP = diameter, so doubled). If all 3 axis are reported, then it is the formula for the radius of a sphere times 2
2) PERP-TO-CL turned on is a little more 'advanced' as in Pcdmis basically 'levels' to the nominal centerline axis and reports the hypotenuse and doubles it.
3) Xact measure with datums(M), no way to tell you since this is WAY up there on the math skill pyramid, as there is datum shift, which you pretty much can't do by hand with a pencil & paper
4) Xact measure without datums(M), should be the same as 1 or 2
sigpic
Originally posted by AndersI
I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.
1) Straight up TP, hypotenuse of the triangle times 2 (hypotenuse = radius, TP = diameter, so doubled). If all 3 axis are reported, then it is the formula for the radius of a sphere times 2
...
For 3 axis is exactly the same as for 2 axis, except that under the square root are the sum of the square of 3 axis deviations instead of 2.
"This is my word... and as such is beyond contestation."
Which is the formula for the radius of a sphere.......
In common parlance, that is not true. If you look up the radius of a sphere, you will not directly find that as an equation. You have to derive it from the equation for a cartesian sphere with a known center (Xsub0, Yxub0, Zsub0) and a known radius, R.
If someone were to Google the radius of a sphere, the equation they are most likely to find is the derivation from the volume of a sphere, which includes pi.
FWIW, I wasn't correcting you, I was expanding on what you said for clarity, for the above reason.
"This is my word... and as such is beyond contestation."
In common parlance, that is not true. If you look up the radius of a sphere, you will not directly find that as an equation. You have to derive it from the equation for a cartesian sphere with a known center (Xsub0, Yxub0, Zsub0) and a known radius, R.
If someone were to Google the radius of a sphere, the equation they are most likely to find is the derivation from the volume of a sphere, which includes pi.
FWIW, I wasn't correcting you, I was expanding on what you said for clarity, for the above reason.
There are many formulas for the radius of a sphere (or a circle) and they are all derived from some other formula. In this case it is a sphere with a known center and a point on its surface.
Therefor, the most basic equation used by PC-DMIS to calculate POSITION (and many other things like T-value) is Pythagorean theorem:
a^2+b^2=c^2.
Ken,
you should tell your engineer that PC-DMIS calculates POSITION the way that the ASME Y14.5 explains it. As he is an engineer, he should know the standard well.
In common parlance, that is not true. If you look up the radius of a sphere, you will not directly find that as an equation. You have to derive it from the equation for a cartesian sphere with a known center (Xsub0, Yxub0, Zsub0) and a known radius, R.
If someone were to Google the radius of a sphere, the equation they are most likely to find is the derivation from the volume of a sphere, which includes pi.
FWIW, I wasn't correcting you, I was expanding on what you said for clarity, for the above reason.
sqrt(Xdev^2+Ydev^2+Zdev^2)= radius of the sphere broken down to the very basics.
It matters not where the center of the sphere is (Xsub0, etc.), from the 'given' center of the sphere (nominal) when you have a point on the surface of the sphere (actual), and you know the difference (deviation) from that point to the center (theo), you can calculate the radius of the sphere with that formula.
sigpic
Originally posted by AndersI
I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.
sqrt(Xdev^2+Ydev^2+Zdev^2)= radius of the sphere broken down to the very basics.
It matters not where the center of the sphere is (Xsub0, etc.), from the 'given' center of the sphere (nominal) when you have a point on the surface of the sphere (actual), and you know the difference (deviation) from that point to the center (theo), you can calculate the radius of the sphere with that formula.
It certainly does. How do you think you know the deviation? Xdev = Xactual - Xsub0. (Xsub0 is X subscript 0, or X naught)
Knowing this comes from knowing the XYZ nominal, which is the center of the deviation sphere. If you didn't know the nominal(aka center), you couldn't know the deviation. It is the same for TP or for 'T' values.
"This is my word... and as such is beyond contestation."
It certainly does. How do you think you know the deviation? Xdev = Xactual - Xsub0. (Xsub0 is X subscript 0, or X naught)
Knowing this comes from knowing the XYZ nominal, which is the center of the deviation sphere. If you didn't know the nominal(aka center), you couldn't know the deviation. It is the same for TP or for 'T' values.
What you won't find by Google searching is R=sqrt(Xdev^2+Ydev^2+Zdev^2).
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,...
I'm fairly new to PCD, but 18 years programming. I have a position callout (bi-lateral not diametric) of .001 to -A-. -A- is a cylinder, and the position...
Comment