Making the Beams
I turned my attention to the beams that would support the top. I had enough 1-3⁄4″ stock remaining to make them (again with the quartersawn faces on the thickness), and I milled them down to 1-1⁄2″ thick. I cut the beams 2″ wide to match the legs and to a final length of 23″. The bevels on the beams start 2″ from the ends and taper down to 1/4″. I cut them vertically on the table saw, clamping them to a purpose-built jig that rides on the fence. At this point, I began to think about how to attach the top and decided that pocket-hole screws were my best option. So, before going any further, I clamped a couple of long scrap pieces to the drill press table to hold the beams securely at an angle relative to the drill bit, tweaked them a bit to center them and leave a sufficient thickness of wood for the screws to bear on, and bored five pocket holes in the inside face of each beam with a 3/8″ Forstner bit. I then went back and drilled oversize holes for the screws centered in the pockets — it allows for seasonal movement in the top.
With the dry-fitting done, I disassembled the trestles and laid out the mortises for the stretchers. I centered them on the reference marks I had taken from the spacer pieces, starting them 7/8″ from the top of the bottom rails to leave a little step-down when the 3/4″ shelf was installed. I made the stretchers from 3/4″ stock, since their thickness isn’t visible. I cut the tenons with my dado blade, then laid out and cut the 3/8″-wide by 3/4″-long mortises for the wedges that lock the stretchers in place. As is standard practice, mortises extend just a hair inside the thickness of the lower rails, so the wedges pull the stretchers tight.
In the last steps before final assembly, I sanded everything to 220-grit and routed the bevels on the edges and bottoms of the legs and on the ends of the exposed tenons on the bottom rails and stretchers.
I started by gluing the lower rails into the legs, carefully brushing glue on only the 2″ of the tenons that would be buried in the legs’ mortises. I then glued the outer edges of the outer slats (but not the tops and bottoms) into the grooves on the legs. I centered the middle slat in the groove but did not glue it, but I did glue my 1-1⁄4″-long spacers into the grooves on either side — making sure they were centered over the mortises below. I added the next two slats, again without glue, and finally I could measure and cut the remaining spacer lengths exactly. These spacers are approximately 1-1⁄2″, but this distance may vary slightly.
Then I added the top rail and did the same process over again on top (the outer filler pieces on the top are, of course, narrower than those on the bottom) and clamped the whole thing up. When the trestle assemblies were dry, I decided which sides looked best and would face out … and I glued the top support beams to the top rails. They are flush with the legs and present an even overhang on both sides (pocket holes to the inside). I clamped them tight, drilled countersunk screw holes centered on each leg and screwed the beams down to the legs. To keep the three middle slats from rattling if they ever shrank, I shot a brad into the top and bottom of each from the back side of the top and bottom rails. Finally, I glued the stretchers into the mortises on the bottom rails and clamped the assembly overnight. I left room next to the clamps to fit and glue in the wedges in the stretchers’ mortises.
The shelf came next. I chose some nicely figured 3/4″ boards and edgeglued them up into the 8-3⁄8″-wide shelf. When they were dry and finish-sanded to 220-grit, I cut the shelf to final length, placed it on top of the stretchers, centered it so it hit just inside the outer edges of the 2nd and 4th slats in the trestles and clamped it in place. I then flipped the assembly over, cut two shelf blocks to the width of the space between the stretchers (with the grain running the same direction as the shelf), spread glue on one end of each (keeping the glue in the center so it wouldn’t squeeze out and stick the blocks to the stretchers or the bottom rails) and dropped them into the space, tight against the inside faces of the bottom rails. Once the glue set, I took the shelf off and drilled countersunk holes to screw the blocking to the shelf on from the bottom. The shelf simply drops into place — gravity keeps it there nicely.