When it comes to nailing on box bottoms, there are two main ways of doing it. One is to put the bottom on the carcase, and nail up through the bottom into the sides. The second is to fit the bottom in the carcase, and nail through the sides into the bottom. I prefer the second method for a variety of reasons, but primarily because I feel it looks cleaner, and less like the bottom was an afterthought.
First is to give ourselves a centerline. This is pretty crucial to making sure we don’t punch a nail through the interior of the tray. We know the bottom is a half-inch thick, so lightly marking a line a quarter-inch up puts us right in the center of our bottom piece. Since the grain in our bottom piece runs along the length of our tray, most of our nails will go there, so it will fasten edge grain to edge grain, and consequently hold well. We’ll put a couple nails in the bottom piece’s end grain on the tray’s short ends, but those are more to restrain cupping than to hold a load.
We’re going to use some pins here because we’re going to set them below the surface of the wood. Decorative nails are a different story. BEFORE YOU START driving nails, make sure to blunt the ends of your nails. This will help keep you from splitting the sides as you drive them. Instead of poking through the fibers and splitting them apart, it mashes its way on through. Seems counterintuitive, but this is about the only time you don’t want something sharp in woodworking. Get your nails close to the surface of the wood, and use a proper nailset to put them in the rest of the way. Trying to plane hammer dimples out of your tray is not going to make you happy. Since we’re going to set and fill behind these nails, I’m not too worried about spacing. Eyeballing evenness is acceptable. If we were using screws or decorative nails, though, I would step the spacing off with dividers so that all my heads were exactly even. And the screw heads would be clocked.
Once you have all your nails driven in and set, we are going to fill the holes left behind with some shopmade putty instead of the epoxy-like “wood filler” from the hardware store. Take an offcut of whatever you are working with (white pine in this case), and use a fine rasp to make a pile of dust. DON’T use coarse sandpaper to do this because you’ll get little pieces of grit in your wood dust.
Now take your glue, and put a drop in your wood dust. Mix it with your fingers into a little hamster pellet of putty. Then try to pack it into your nail hole. Really try to work it in there. Keep going until you have a little cap of gunk on the top of your wood. It takes a little faith here because it looks like some pine beetles used your project for a litter box. But don’t worry! It gets better.
Let your termite snot harden overnight. Pare off most of your cap, and then sand flush, making sure not to leave any glue residue behind, or your finish won’t stick right. Presto changeo! You have nicely filled nail holes, ready to paint. We’ll finish up (see what I did there?) tomorrow!