On Jun 8, 2:31*pm, "Joe J" wrote:
"John" wrote in message

...

If you want to use your 3" screws, you're going to need to drill
shanks in your 2x4's (shanks are holes that are wide enough so that
your screw can slide through without the thread catching -- you don't
want the thread catching both the 2x4 and the wall), so if you use a
counter-sync/shank combo, you should be be able to embed the 3" screws
a 1/2" into the wood easily enough. *If you don't have one of those,
you might want to consider buying some 3 1/2 - 4" screws that have no
thread the top 1 1/2". *That way you won't have to do any shanking,
and the shelves go up faster.

John

Why wouldn't I want the screw to catch both the 2x4 and the wall stud?
Seems to me that would make a nice tight fit.

When you snug the 2x up to the wall there is no gap. If the threads
are sunk into both boards, one or the other has to strip out to close
the gap. You don't want that force stripping the threads out of the
hole in wall stud.