It seems to me that these would be the perfect tool for changing out ads or trailers before a platterised feature: simply place one in a split spool, wind leaders/snipes/ads/trailers onto it head out, remove the core, drop in the film roll, splice, and you're done!
You could achieve the same effect by building up junk film onto a 3 inch core, but it's not quite as spiffy, is it?
Thoughts?
Goldberg makes a split reel that has a collapsible center ring that is exactly what you are looking for. Contact your booth suppplier and request one.
Goldberg also makes a 6000' split reel and for that matter, will make anything you need (for a price).
One of the booths I worked in we were using half Strong, half Christie platters. The Christie center rings are quite a bit larger in diameter than the Strong rings. One of the techs had drilled holes in the Strong platters to accomidate the Christie rings. This made moving prints around easier. When I changed out trailers I would just build them up on the unused Strong rings, then pull the Christie ring and any trailers out of the center, and then just drop the new ones right in. I could usually get two to three new trailers on a Strong ring and have no problem getting them in the center.
At another theater I worked at with Strong platters they had purchased special center rings that were twice the size in diameter as the normal Strong rings. If we were going to change out trailers we would take up the film on the large rings for the next run. While it was running we would build up new trailers on the normal Strong ring and then after the show was out we would just drop the new trailers in the center, splice, and run.
I have also seen some make-shift spacers made out of 3/4" plywood that would fit around an existing center ring and ad an additional 12" of diameter to the center. This would work pretty good, since getting a theater to spring for additional equipment is like squeezing water out of a dry spounge.
Good luck, hope this helps.
-David Miller
Projectionist, Seattle Cinerama
millerdk@plu.edu