I need to move a chandelier to center it over a dining-room table. There's a good chance that the new fixture location will be between the ceiling joists and I'll have to install some blocking or some sort of bracket to mount the box to.

Putting up 2x4 blocking would require making a fairly sizable hole in the ceiling. If I can avoid this, I'd like to.

If I could use some sort of expandable mmetal bracket that I could extend once I got it into the ceiling, I could use a bit extension and I might be able to screw it in place through the 4" hole I make for the box. However, all the bracket-boxes I've ever seen are much too flimsy for this application. Any ideas?

Thanks.

-John