Please excuse the original author. I didn't change his design. It was an official part and approved not too long ago.
I have now remodeled the grooves and subfiled as requested. There may be future use cases where the grooves or the handle might be reused.

now the inner cyli forms a "dent"
you should use 1 16 1.1481 -36 0 3 0 0 0 4 0 0 0 6 3-16cylo.dat instead of the 1-8cylo to match the old geometry...
you can also use the 3-16chrde instead of chrd + edge separately.
if some surfaces reach a bit inside, that isnt that bad.

The dent shape follows the physical part much more accurately than the earlier squeezed cylinder (The rotated squeezed cylinder was originally chosen to minimize the number of surfaces to be drawn - not to follow the shape of the physical part). The physical part has an even more pronounced dent than the modeled part because the model extends the groove until the next available cylinder vertex. The actual groove exit point should be approximately in the middle of two of the vertices on the outer cylinder. Although having the same curvature from the bottom of the groove to the outer cylinder, the vertical dimension is aggravated to a 90 degree angle, while the horizontal dimension is reduced to about half its slopeness. Further reduction in slopeness is not motivated.

Will change design to better follow the physical part. This handle groove may be used with 4 use cases of the parent part (3 parallel grooves), flippers with handle 43871 (3 parallel grooves), broom 70675 (5 parallel grooves), and guitar 65114 (5 parallel grooves).

This groove shape fits the following parts:
* broom 70675 (5 narrow grooves)
* guitar 65114 (5 narrow grooves)
* flag 31925
* hand sign 41759
* seaweed 43852
* brush 24807
* flippers with handle 43871

now the chrd overlaps the ring prim...
(why the R4.8? at R5 there would be only 4 decimals like the base prim)

Removed superfluous chords. Changed inner radius to 5. Thanks Rene for the suggestion!