“So Zack what do you want for Xmass?” “A portable desk to rest my laptop on” he says. Hmmm – after doing some web research to see what is being produced for the masses, I came up with a few design criteria. Big enough for the laptop when using a mouse to the side. Adjustable height in case he puts on a few Xmass pounds.
I started out by laminating some luan mahogony to a 1/2 inch birch plywood base. After that dried and I cut the lamination to the finish size I made some 1 inch oak trim to hide the plywood edges. I glued the oak to the top on my benchtop, so I cut use my Jorgensen holddowns on the back. Note to self - if you do this again, use some poster board stock to slightly recess the veneer below the top of the sides.
Oak was used for the slides. The outer slide is routed to accept the inner one. I left the bottom rounded and just shaped the inner piece to match the radius. The center of the outer side is drilled for the tightening knob ( 1/4 inch hole). I inner slide is placed in the outer, the assembly turned over, and a pencil used to indicate the required boundaries of the slot that is then cut with the scrollsaw, and cleanup on the router table. It is slightly oversized to allow easy sliding (both the slot, and the outer slide).
Now the slides are mortised into a top and bottom rail. The bottom rail has a through mortise, which can be sanded flush after the marine epoxy used in assembly cures. Now the location of the top (inner) slide can be determined. Place the inner slides into the runners and mark their spacing on the top rail. These are blind mortises. A bit of the appropriate diameter was used to drill out most of the mortise waste, and then a chisel used to square up the sides. I used wood glue on the top mortises, the top slides were inserted into their bottom mates while the glue dried to assure the correct alighnment.
Now I made the knobs. I know, you can buy them for a couple of buck each, but I have all this oak scrap I like to use for something ;). I started out with 1/2 inch chunk that I drilled 1/4 inch holes at the location of the nuts. I then traced around the outside of the nut (with a carriage bolt through it into the hole). I then mortised out recesses for the nut. Since this is a fairly repetitive task, I made 6 knobs when I only needed two this project. Now I placed the nuts in the mortises, and glued a 1/4 inch oak board to the 1/2 inch one with the nuts in it. I stuffed small bits of paper toweling inside the nuts, to keep the glue out. After the glue dried, I drilled out the paper toweling and on through to the other side with and unsized brad point bit until only the point came through with my drillpress. The board was fllipped and a 1/4 inch brad point could be accurately positioned to remove the remaining waste without damaging either the bit or the nut threads. Now a carriage bolt was placed through a store bought plactic knob, screwed into the 1/4 inch nut in the board blank, and a pencil used to trace around the knob lobes. A 1/2 inch brad point bit was used to remove the waste at each inner know lobe as seen in the photo. Now the scrollsaw was used to cut out each individual knob, and a 1/2 inch sanding drum used to round the outside edges. Finally a roundover bit in the router table took off the sharp edges of the finished knob.
Finished pieces before assembly. Top rail is scewed into the bottom of the top.
Finished lap desk with the first coat of Polyurethane applied. Watco 'Natural' Danish Oil was applied to all the pieces 48 hours prior to this.