any thoughts on building a very large working fan as a means of changing a scene ... closed for one scene and open for another look

This one has me stumped a little as well Joan.
I think it might be a Vegas style or folleys type, which  opens up from a ground row & closes off the scene, similar to a chineese or spanish one.
Swinging back to closing,
thus opening the scene.
When it is closed the scene is open
& when it's open, the scene is closed!
I hope that's in line with your thinking Dramamamastill?

I love to hear about new ideas for set changes...and this one sounds like a very interesting one.  Consider how this fan will be opened and how much space it is going to use.  How do you get it off when you are done with it?  How do you stop it from falling over?  Does it add significantly to the story or is it a large distraction to the audience.....no matter how unique and pretty it is?  I don't want to discourage you but there is a reason why most set changes ( from elementary school to Broadway) are done with a quick black out and a change of props.  One of the pitfalls of amateur theater ( and I am as guilty as the rest) is long, drawn out set changes.  If the audience is left in the dark for even 10 seconds they are detaching from the story, getting bored and thinking about other things.  If possible make one scene flow into the other as simply as possible and don't be afraid to leave some of the background to the imagination of the audience.  They know this is the theater and not a film. That being said...if you go forward with this please keep us posted on your progress and let us know what you learned from building a giant fan.

With the fabric & attaching the ribs/slats, I would think just make up a milky solution of white wood glue & water. But this depends on the type of material to be used, cotton products would be fine. But you will have to find an adhesive that suites a man made fabric & didn't melt it.
There are a number of spray on glues that could help, try it on a sample first, do a squirt before you buy. There again velco can work great, as an alternitive.
The biggest thing to me would be the pivot mechanism & I believe he may be better thinking of of two half fans, one on each side (U/S OP & PS) slightly off set so the sails over lap or the outer  edge of the fan could be squared off to close completly together.
Which would be easy to operate by haul lines off stage, masked by the Legs.
However with the centre stage pillar a dual pivot, working in the oposite direction may be needed.
The opening & closing could be worked from the Fly's on one dropper line. Using a counter weight on a slide rail, attached upstage behind the pillar. When the fan is opened, the dropper line pulls up the counter weight to the head of the pillar. Then snotted off [tied] to hold the counter weight & when it is to be closed [folded back to the pillar], the counterweight is lowered.
One other thing with the fabric is find some similar to parachute silk, which folds easily & offers little or no surface resistance.
With the pivot, one thing that comjes to mind, is a short stub car wheal axle , that can picked up from a wreckers. Using the wheal studs to bolt down a boss, that holds the rib/slats. is an easy way to go. as there would be a fair wieght hauling in the fan sails. There again a bicycle fixed axlw wheal may work just as well]
The last time I worked on something like this, was when I was a wee one working on the Folleys Bergere, except they used nude Follettes as the rib/splats, covered with see thru gauze fabric. Using the transposition of lighting, it was innovative &  revealing. [remembering I was very young & innocent at the time?]
This is interesting - keep us informed Mamma - it's great to be regarded as one of the 'kids'.

It is part of a design for a high school production of The King and I