Recommended screws for mounting projector and motorized screen

For my projector mount (through drywall and into dimensional lumber bracing between ceiling joists), I used four 2.5" lag screws.

Mount to drywall only: not recommended. You could attach a piece of plywood to the ceiling (as long as you anchor into framing) and attach the projector mount to that.

Mount to framing under drywall: #10 wood screws or 3/16" lag screws that penetrate into the wood at least 1.5". don't use deck screws or (gasp) drywall screws.

If you haven't put the drywall up yet, nothing says you can't add a joist right where you want to mount the PJ. Joists only have a maximum spacing requirement. There is no minimum requirement. You can also span between joists with some 2x4s to make your support piece.

Alternatively, if you want to have some room for adjustment, install a span of ¾ plywood flush between the span of two joists (right behind the drywall) so that you have the support of the drywall to screw into, without the visibility of a big slab of plywood stuck to the outside of the drywall on the ceiling of your room.

As for drill sizing for pilot holes, if you are running into pine 2x material or plywood, undersizing the bit isn't too big of an issue as the wood will likely accommodate it. Although some of the overly dry kiln-dried studs are prone to splitting if you look at them wrong.

In any case, I usually size the bit so that it is the same size as the shank of the screw, but the flutes of the screw fully reach out beyond the bit.

-Suntan