Position/Concentricity - Cylinders or Circles?

[keego]

I have a tube with a bore at each end. Outside of the tube is primary datum. Would you then measure the bore features as cylinders, (3d), or circles, (2d), to report postion and/or concentricity?

[dph51]

measure each bore at 2depths from each end and report positions.

[keego]

measure each bore at 2depths from each end and report positions.

Ok, measure them as cylinders or circles? Cylinders are 3d, and circles are 2d. I have 2 enginerds that are arguing over this.

[John Riggins]

If you are aligned to the OD it should not make any difference.
If you want to know the orientation of the ID to the OD you would use cylinders.
If you just need location at each end circles should work.

[lambo]

Position: (3D) what dph51 said or I would measure both ends as cylinders and then report “From the worst end of axis” or “From both ends of axis” but never “From axis average”

Concentricity = Circular runout (sort of...): Concentricity is applied to each cross section therefore I would treat it as 2D….

HTH

[dph51]

Ok, measure them as cylinders or circles? Cylinders are 3d, and circles are 2d. I have 2 enginerds that are arguing over this.

shoot one of the enginerds.

[Addison Wood]

Level to the O.D. datum. The only differences you're going to see in I.D. position or concentricity are if you measure as a circle the position of the circle will report out from its center along the datum axis. If you measure as a cylinder the position that reports out will be from the baricenter (sp?) of the cylinder along the datum axis. Coaxiality is a whole other can of worms and requires all cylinders.

[dph51]

[QUOTE=lambo;292156]Position: (3D) what dph51 said or I would measure both ends as cylinders and then report “From the worst end of axis” or “From both ends of axis” but never “From axis average”


As Lambo says. Check the help file under position/axial feature

From Axis average > centroid of axial feature
From Start point > start point of axial feaure
From End point > at end point of axial feature
From worst end of axis > outputs from worst end case
From both ends > outputs position from both ends