|Originally posted by BGPGuy
I love this post! Thank you! I would only add that the third piece of unistrut when running parallel with joists limits your ability to raise/lower projector.
True, but don't forget that while this setup is used by many because it's cheap and flexible, you should still be getting your install correct to within an inch or so. Then use the flexibility of the Unistrut to move the projector in all 6 directions by an inch or two at the most until it's bang-on. This setup is not meant to be able to allow you to raise/lower the unit by 4-5", or to serve you for 2-3 projectors with different height requirements and throw distances.
If you change your projector, spend the $5 for new bolts! :)