Hi Guy, yes Phiro's method using the Twist command is better, it should give high accuracy while at the same time less work to set up since you only need one profile curve.

The Twist command is under Transform > Deform > Twist:
https://moi3d.com/4.0/docs/moi_command_reference8.htm#twist

Thanks Phiro!

- Michael

Excellent! Thank you so much!

Hi GuyLuke,

As pointed out in the comments, the video modeling could be less complex, with better geometry tools.

A 2d profile of one groove is useful. This can be done in metric units.

Switching to inches, one helix is useful. The helix rotates 360 degrees in ten inches.
Left or right handed.

Sweep the helix with the profile to create one groove.

Circular array the groove, by 6 (copies).

Etc.

-Brian
(Have not yet viewed your .3dm.)
( There is more than one method. )