I have been prevented from final sanding and finishing of the stave assembly because I still needed to drill the locator holes in the ledges for the center bracket.  I was waiting until the shade was finished in order to figure out the locator hole placement in case I needed to spread the staves slightly in order for the shade to fit correctly.  I'm still waiting for the shade fabric to arrive, and have been stalled-out due to my planned order of operations.

I finally had enough of the waiting and came up with a bracket with some flexibility built-in.  I said I wouldn't do it, but perhaps I'll be forgiven due to its simplicity.  I've just added a series of locator holes on each wing, each hole at a slightly greater distance from the center.  If I find that the step-up in radius is too great, I can always make this part again.

Now I can drill the holes in the ledges at a fixed distance from the edge.

These 1/8" brass pins are just a friction fit.

That should work just fine.  I have the bracket mounted in the neutral position, and each successive position will push the staves out a little bit.   Now I can complete the hand sanding and start applying finish.

As luck would have it, the fabric is due to arrive tomorrow.  Well, fabric, you can just sit and wait your turn.