blueman wrote:
"George E. Cawthon" writes:
Why don't you use the standard metal shelf support rails (the ones
with slots that use metal V support clips) that are dadoed into the
shelf sides sides?

I personally don't like the rails because they are more obtrusive.
Sure 1/4" will support a heavier load than 5mm. 1/4" is about 6.4 mm.
But you are talking about shear strength. I can't imagine how much
weight a shelf would need to shear off four 1/4" pins (dowels).
Probably more than one could put on a shelf using 12" high books.

Sounds like I will be OK with the 1/4" pins (though I have some sets
of books that as big as 14"x12"_

My question was not so much about breaking the pins (which I imagine
would be hard to do) as about tearing out the hole.
What I really wanted to know is whether the 1/4" pin system is
significantly stronger than the 5mm system to justify the bigger and
more obtrusive 1/4" holes.

No, don't use any kind of sleeve. just make sure the pins are snug in
holes that are accurately at right angles to the shelf side and are
drilled to a depth of 1/2" and the pins extend about 1/4" from the
surface.

Do the sleeves add no strength advantages then?

Thanks

I suggest you make a simple test shelf. The shelf
only has to be 3-4 inches high. Use the same
thickness of materials sides, pins, and shelf that
you want to test. The construction can be very
simple just two uprights braced and nailed so
they won't spread out. Knock it together then
have one person stand in the middle of the shelf
(150-200 pounds), then try two people near each
end (300-400 pounds). If the pins break you only
fall 3-4 inches.

Please note that you want the shelves to fit
between the uprights with as little extra space as
possible, just enough so that you can move the
shelves.

BTW, if you keep books on the shelves, you will
never see those metal rails, and even if you don't
they won't be obtrusive if you paint them the same
color as the wood.