Wrap Feature around X Axis Problem

Good day to you all, I am having problems with the X axis Wrapping on a job.

I want to cut a 60.0 degrees slot x0.250 deep on the OD of a 3.500 dia bar.


I have calculated the length of the arc to be 1.832" at the 3.5 dia and drawn the curve over the part and then created this as a side feature.


I thought I could simply use the "Wrap Feature Around X Axis" tick box to generate the feature.


The angle cut has been measured by inspection and is showing 54.0 Degrees.


I then proceeded to re calculate the arc length at the 3.0 dia and created a new curve/feature at -0.249 with a 0.001 depth of cut. This time the included angle measured 53.0 deg.


Any thoughts on what I am doing wrong?


Many thanks.

Update, I think I have found the answer to my question. From Feature Cam Help-

"When milling features are wrapped around the index axis, one coordinate axis is converted from linear moves into rotational moves. For wrapping around the X axis, the Y axis moves are converted into C axis rotations. For simple wrapping the NC code is relatively simple, but the walls of the resulting feature are not perpendicular to the index axis"

and

"If you require perpendicular sides, you must have a lathe or mill with X-axis, C-axis, and Y-axis motion. (I assume this is referring to full 5 axis simultaneous axis movement) "To program your feature to have perpendicular sides you must select Wrap feature around X-axis and also select Cut sides perpendicular to index axis. Features cut with this option have sides that are perpendicular to the index axis"

Attachment 454342

Thanks