Got a couple hours of free time this afternoon to lug it all out and have a go at fastening the shelf plywood to the top shelf frame. I’m doing this shelf first for a couple of reasons. Primarily, because if I screw it up I don’t have to see the surface of it as it will be above eye level and I can learn from those mistakes before I fasten the other shelves. Also, this particular shelf will require two pieces of plywood as opposed to the others which get monolithic pieces.
The “fog” in the pictures is from the lens condensing thanks to ridiculous humidity outside.
That the shelf is 71 5/8” wide and each piece of ply is only 4’ wide is not something I accounted for when spacing the framing members. The members are spaced evenly along the length of the frame on center which makes good logical sense. In order to have the 4’ termination of the board fall dead center of a member would require the members to be spaced 12” on center with the total shelf width being 72”. I lost those 3/8’ to saw kerfs and Home Depot’s imperfect cutting (which was necessary to get the stuff into my car which you knew if you were following earlier installments). Those 3/8” were cut out of the length of the total ply making these shelves a bit too thick for the frame and the rest of the whole assembly more fun to calculate and cut for.
Here, on the top shelf I elected to have the extra lip stick off the front in case I ever decide to fasten the back supports to my masonry wall.
The good news about the 4’ widths of ply is I have factory edges on all 4 ends which makes butting the pieces painless. The only challenge was cutting the long piece to length (read not too long) and preferably square. I stuck the cut edge on the protruding lip side so I had factory edges to square the first piece on to the frame. Because I had taken the time to redo the frame into perfect flush and square this went easily and mated well. I still clamped the piece on to secure it for the actual fastening. I could have used a story stick or just measured out each overlay line to make sure I hit the center of each member but I cheated and used a chalk line which I just aligned with the center of the screw heads on each before popping a line onto the surface. This stuff was a pain to sand out and it didn’t go completely away so I am not sure I would use this technique for the other shelves.
I measured 3”, 6” and 9” hole marks from the front lip edge (not my squarest edge in restrospect) despite actual depth being more like 1’ 1/4”. I drilled pilot holes before sinking 2” drywall screws. I offset the shared member holes from center by 1/8” inch to allow some room for side by side screws.
For the cut piece I simply clamped it flash and square with the already mounted piece and marked the underside with a pencil where it met the outside edge, flipped it over and stuck the longer waste side against the sister piece and clamped it to the frame to prepare the cut. Until now all my sawing has been squared against a rafter square but for this I attempted to add a rather nice level as a straightedge against the square but my saw motor would not clear the level so I ended up free handing the last inch or so and had my shop assistant perform her first duty ever, making sure the piece didn’t hit the ground on separation.
I flipped it back over and mated the factory edges, noted I had gauged the outside cut perfectly with no overhand or coming short and fastened in the same manner. The last challenge was fastening to the shared member with less than half the member to attach to. I placed a screw hed so that it was just shy of the edge and scribed where the center of the head was then marked my 3”, 6” and 9” holes along that scribe line. When I piloted these holes I gave them a very slight inward angle maybe 3 or 4 degrees so it would not hit the neighboring screws. This went well with a small cracking in only one hole as you can see in the picture.