Manufacturing marks or wear?

[Paul N-M]

From an engineering rather than Austin 7 perspective, aren't the marks too broad to be wear marks? For the mating part to be able to make so many clearly visible individual grooves it would need to either have this profile on every rubbing part to wear a replica profile or be able to move  side to side by 3-4 mm and so be an incredible loose mating fit to chatter around so much? Is that even possible with the size of spline without the mating splines being about 1mm thick to give the lateral movement required?
Also if chatter is the cause and the splines can move around enough to produce multiple grooves then why are there no slightly lateral scratches, why is every mark perfectly radial?
And is the diameter of the wear marks no much larger than that of the mating splines, or is that an optical illusion?
It just doesn't look possible for a mating part to wear such an identical and yet severe chatter against every spline. If you look at the marks on the picture then every one is truly identical, they are like finger prints, right down to a rounded profile to the top right and small square missing from the 'cuts' on the bottom right of the profile as viewed in the picture, along with the location of a deeper groove at the top.

There is no way that wear from different points of contact could produce such identical marks. In my opinion it has to be tooling of some type, where it was set up with identical passes and thus caused identical marks.

Andy B

I've just offered up a plate to a gear box to see if any contact from the female box splines could be made to the 'dome' of the male spline plate even when its pushed fully into the casing. Answer is no. Marks are caused by something else.

Paul N-M