On Mon, 11 Sep 2006 03:39:16 GMT, blueman wrote:

I'm building a bookcase with adjustable shelves with a 46" span that
will likely carry some heavy books.

- Can I assume that all other things being equal, 1/4" pins will support
a heavier load than 5mm pins (since the diameter is larger)?
Assume the pins are cheap grade 2 steel. That gives a shear strength
in excess of 200 lbs. Using 4 pins per shelf gives a shear load in
excess of 800 lbs. Putting an extra pin at the back centre of the
shelf helps keep the sag to a minimum. The pins will not fail.

- Will using a "sleeve" in the shelf pin hole add strength and prevent
tearout from too heavy a load?
A sleeve is a beautiful finish to any blank holes (adjustable shelves,
right? They also help support (if that's the right word) the hole and
keep it from deforming. The part that fails is the wood. It gets
possible tear out when load is applied.

- Would adding a third parallel column of pins on each side support
*materially* improve the strength?
The 3rd row should be in the back centre. They stay out of the way
and are good looking with the sleeves.

- Finally, any feedback on the Rockler Shelving Jig? (it seems to do
the job, comes with self-centering bits, and is affordable)

Can't help on the Rockler jig. I use strips of peg board - the ones
with holes 2" OC.