Drywall screws are hardened steel, so indeed have a lot of tensile strength per unit of cross sectional area (i.e., psi tensile strength.) However, because they are designed to pierce through undrilled drywall without damaging the drywall too badly, and through undrilled wood without splintering the wood, they have a pretty skinny cross sectional area.
A lag screw, like a 1/4" or 5/16" lag screw, wouldn't be hardened like a drywall screw (so it might have let's say 50% the psi tensile strength, let's say), but it might have 10x the cross sectional area, so would be able to take 500% the load of a drywall screw before failing. Also, if its load were exceeded it would bend instead of snap - (good for the TV I'd say.)
FYI, I've got a somewhat similar wall-mount bracket for a TV in my living room, with an articulating arm that can extend the TV as far as 28" away from the surface of the wall. It mounts on a flat surface, not a corner like yours. The portion of the steel bracket contacting the wall (drywall with wood stud behind) is 12" tall, and is mounted with 3 vertically oriented lag screws (with a center to center spacing of 5.5".) I'm guessing they are 1/4" or 5/16" lag screws. There are actually provisions for two columns of screws (6 total) but I am only using one of the columns of screw holes (Going into a single stud.)
The newer LCD TVs with LED-backlighting are really thin and lightweight compared to the LCDs with flourescent backlighting, and would let you get away with a much less substantial mounting bracket I would think. I do think it is cool to make your own mounting bracket though. I like the corner mounting idea you used.
Last edited by jakeru; 02-25-2012 at 05:53 PM.
'13 Everlast 255EXT
'07 Everlast Super200P
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