Well the original prop was hand machined, likely without much in the way of design drawings, so it's no surprise there are plenty of "inconvenient measurements". The other thing to consider is that the original was likely machined using imperial measurements, so that might influence some numbers.
For instance, my own scaling and estimations of this prop show that the flat spots between the pommel cubes were potentially milled out using a 5/16" end mill. I don't know if people more well versed in this prop (like Anakin Starkiller, BRRogers, DaveP, and others I'm sure) would agree with that finding, but it makes some sense to me based off of the general scaling of things and trying to think what would likely have been done to create the original.
On another note, the "V" grooves in the grip section seem to have a 60° angle, which is a pretty common piece of tooling for cutting threads. My thinking is that they simply plunged that tool into the grip section by eye, reaching varying cut depths and at inconsistent intervals, while also not having the tool completely perpendicular to the work piece, resulting in the wonky angles and varying width of grip rings. This thing is full of wacky inconsistencies!
-EDIT-
Looks like Anakin Starkiller responded with a lot of the same points at the same time!
