Drafting / Light Table

Here is a knockdown drafting table which can double as a light table. It can be used flat with a height of 36 inches (Counter height), or the rear raised to an incline of 33 degrees.

After cutting the birch plywood top to size, I glued 1 1/4 inch oak edging to all sides. I used a caul to exert even clamping pressure over the entire length of the side.

After the glue dried I used a straight spoke shave to flush the trim with the top. A spoke shave is less likely to damage the top than sanding or planing.

Next I cut out the center of the top for the light to shine through. I then routed a 1 1/2 inch rabbit around each side to allow the 1/4 inch thick plexiglass to recess flush with the top.

Next I started working on the base which is 30 inches long, 2 1/4 inches wide and 1 3/8 inch thick. The pedestal pieces were shaped and then glued to the base. After finish sanding, the 2 1/4 inch deep offset mortises were roughed out at the drill press.

The mortises were completed with chisels, I clamped a block next the edge I was working on to help keep the chisel straight.

Next I filled voids in the rabbet with RockHard Putty and then painted it. I then finished the top with Watco Natural Danish Oil.

After mounting the oak bracket that allows the top to be attached to the base, I mounted steel electrical boxes and ran pvc conduit with 14 gauge wire to the switch and two plastic light fixtures. Energy efficient spirol flourescent bulbs will be used to reduce the amount of heat generated while in light table mode. The round light fixtures were cut straight on two sides to a width of 2 1/4 inches so they can be mounted to the inside of the oak brackets.

A cover was made out of 1/4 inch plywood to protect the bulbs. The inside of the cover was painted white to provide a reflective surface for the light. The cover is attached to the four blocks that can be seen on the inside of the oak bracket on the previous photo.

I now started working on the legs. Each of the four legs consist of 2 pieces, a 32 inch stationary member that was glued into the mortise in the base, and a sliding piece that allows the table to be raised and tilted. The front legs can be raised 9 inches, and the rear legs 21 inches. After drilling 1/4 inch holes at the top and bottom of each slot in the upper leg section, the area inbetween was cut using the fense on the table saw. This worked better for me than using a router bit. The material left at each end of the cut was removed with a flush cutting hand saw.

Here are all the base pieces after being finished with Watco Danish Oil. Also notice the brackets that attach to the top. You can see the series of seven holes at the rear of bracket which allow the rear of the table to tilt. You can also see the side supports on the stationary portion of the legs which guide the upper sliding legs.

After assembly of the four legs to the base, the top was temporarily attached to square up the assembly and provide measurements for the top and bottom braces.

After the top and bottom braces were installed, the base was turned on its side to install the cross bracing. The cross braces are essential, because otherwise the base provides no lateral stability. The base was adjusted (racked) until the two diagonal measurements were equal. In this view you can see the T-nuts used for the bottom braces and in the stationary legs which align with the slots in the upper sliding legs sections. The diagonal cross members are attached to the stationary leg sections with blocks which also have T-nuts. This allows the base to be broken down into right and left halves when moving.

Here is a picture with the light turned on in light table mode.

Here you can see the pencil ledge installed, and a T-square resting on the top edge.

Hand drawn plans until I get it entered into Google Sketch. Note: this drawing has been corrected from the original post.

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