On Tue, 16 Oct 2018 09:21:37 -0400, Jack wrote:

On 10/15/2018 4:37 PM, William Ahern wrote:

I'm a novice. I've been building garage shelving the hard way by
meticulously edge gluing 1"x6"x8' pine boards to practice technique. I'm
preparing to edge glue some 2"x12"x4' douglas fir for heavy-duty rolling
shelves (previous shelves hung on wall brackets). I bought some cheap
dimensional douglas fir that was already sufficiently dry but cupped, unlike
the pine boards which were flat enough. But I lack a planer and am not
particularly interested in buying one. (The point of the shelving is to help
reduce clutter and to get everything off the floor. Adding bulky tools isn't
helping things.) I tried hand planing with a jack-plane but there are too
many knots, and I've decided I don't want to deal with 24' of those (nor pay
for wood that can be easily handtooled, which would be the smart thing).

I'm not a novice and I would not recommend edge gluing cupped 2x12's for
shelving. If you want 22 1/2" shelves, I would recommend plywood. If
you really wish to use 2x lumber, stick with 2x6 or less for the glue
ups. When choosing the lumber, look for quarter sawn or rift cut boards
to reduce/eliminate cupping.

Even if you owned a planer, gluing up flat sawn 2x12's, then planing
them flat, will likely just result in thinner cupped shelves. Wood cups
because of grain direction. Planing it doesn't change that. In fact,
flat sawn lumber can be re-sawn into quarter sawn (the edges of flat
sawn is quarter sawn) then glued up to eliminate warpage. A planer makes
this a relatively easy task.

I'm with you on plywood. If it needs to be stronger/firmer than 3/4"
ply allows, frame it in 1x or 2x pine (on edge, preferably). Dadoing
(ploughing) the edges of the frame to fit the plywood makes for some
very sturdy shelving with solid edges that will take a beating.