Offset of bore with no planar axis?

[[Ow...]]

Everything is in inch units.

The big bore 4.1355 (Gerotor bore) is a direct offset in the Y axis.

How would you constrain/clock this with only the 0.1969 offset as the planar axis and get good repeatability?

I’ve tried measuring the middle bore as a cylinder and constructing a 3D line to intersect with the bottom of the 1.440 face and then the 4.1355 cylinder the same way intersecting with the same face and then creating a line between the two intersects for planar, but the offset always shows the x axis off one way or the other (non -repeatable), which effects the offset dimension.

Each Cylinder is being measured with 3 equally spaced circle paths and then recalled into a 3D line. The alignment is looped.

[[Cl...]]

I recently had a very similar situation. I ended up measuring two circles. One near the top (-A-) and the other near

the bottom of the 4.1355 cylinder and constructing my 3d line that way (Z Spatial). I ended up passing a type-1 GRR <20%.

As far as the planar clocking goes. I don't see a tertiary datum? Could you simply translate by .1969 

[[Ow...]]

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Clark,

What do you mean by translate by 0.1969?

I hope to get time on the CMM this afternoon to double check a few things.

 

[[Cl...]]

Maybe I misunderstood that callout. With no tertiary datum. I'm not sure how I' clock it.

[[Ri...]]

See that "Cross Hair"?

According to ASME Y14.5, that is an implied 90°.

Your offset is 90° from its shown dimension.

The controls for datums A and B control the 90°.

ASME Y14.5 2009

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Edited October 7, 2025

[[Cl...]]

You need to clock something. Create a theoretical line through Ø -B-. Intersect that line with Ø -A- for a point (X+)

Planar rotate about Z -5.44°. (If my math is right) using that intersected point. 

[[Ja...]]

Recall one of the circle paths of the eccentric bore cylinder to a circle feature and clock to that circle.

Another way would be to create a secondary alignment using DATUM B for spatial, x and y origin. Use this secondary alignment to create a geometry best fit alignment for the eccentric bore cylinder and allow rotation around Z axis. Use this GBF alignment for location characteristics.

[[Ow...]]

You all going to hate me, but I finally got back on it and..... the (*#&$@) part was moving :-(.

I am using the line recalled between the intersections for planar.

I do appreciate all of the replies and ideals.

[[Ri...]]

Don't hate the player, hate the game. 😄