Charlie Self wrote:
Larry Jaques questions:

Yeah, if you accidentally drop 4 bowling balls on one
shelf of your glassware hutch at once it might cause the
whole thing to fall.

I've had failures in drywall screws, but it was from a
racking/bending force, not shear force. Have you had a
failure from shear?

I've had heads twist off with very low force--hand driven, in fact.
So there's no chance at all I'll ever have a shear failure in a real
project with one. I simply do not use them except to install
wallboard.

In my home office I have 3 sets of 3 eight foot bookshelves attached to the
wall studs with 2" drywall screws. The shelves are chocked full of mainly
computer programming books, dunno, maybe 1000 lbs on each set of the 3
shelves. They've been up for several years. Any reason I should be
worried? (I don't recall for sure, but I probably drilled a hole for most
of the length before putting in the screws.)

-- Mark