My woodworking projects start with drawings. Lots of them. And a lightbox is an indispensable tool for revising designs and tracing patterns; just lay a sheet of paper over the drawing or photograph to be copied, and the interior light shines through to make tracing easy.
The lightbox uses an inexpensive fixture as the light source, and translucent plastic for the top, available at building supply stores as lenses for drop-in fluorescent fixtures. If you intend on using the surface for cutting, add a tempered glass top over the plastic-just enlarge the top groove to accommodate the extra thickness of glass.
Start by ripping to width enough plywood to make the sides. Next, using a tablesaw, slice the pine strips that conceal the edge of the plywood. Attach the edge strips using glue only. Short lengths of masking tape, applied every few inches or so, hold the strips in position until the glue dries.
When the glue has dried, cut the grooves that will hold the hardboard bottom panel and the plastic top panel. To make the bottom groove, set the depth of the tablesaw blade to 1/4" and run the inside face of the edged plywood over the blade. Nudge the fence over a bit and make another pass to widen the groove. Use a scrap of 1/8" hardboard to test the size of the groove after each pass; it should slide freely in the groove without being sloppy. Make the groove for the plastic top the same way.
The box is assembled with mitre joints at the corners. This conceals both the plywood edge and the grooves you just made. Cut the mitres now with the tablesaw, using the sliding mitre gauge.
Unless you are satisfied with a cut that's just “close” to 45°, forget the blade tilt indicator that is installed on your saw. To set the blade at exactly 45° to the table surface, use a small plastic 45° drafting triangle-available at art supply stores. Raise the blade as high as it will go and tilt it close to 45° (the indicator on your saw can manage this). Now set the base of the triangle on the surface of the table and slide it up to the blade. It will be easy to see what adjustment is necessary to get the blade to exactly 45°.
Cut the hardboard for the bottom and dry fit the four sides and bottom in place. Some more masking tape at the corners will hold everything together. The plastic top needs to slide out to allow access to the light fixture. To do this, shorten one side down to the bottom of the top groove. Mark this now with the box assembled, then take the box apart and rip the side down to size.
Before putting the box back together, drill the vent holes and cut the cord access slot in the appropriate locations. To assemble the box, spread some glue on each of the four corner mitres, and bring the sides together, capturing the hardboard bottom as you do so, white side up. Use a strap clamp or even a few wraps of surgical tubing to hold everything together while it dries.
The last step is to cut the plastic top to size and round its sharp corners using sandpaper. Drop the light fixture into the box, plug it in and flip the switch.
|Part||Material||Size (T x W x L*)||Qty.|
|Top||plastic||1/8" x 11 1/2" x 14 1/2"||1|
|Bottom||hardboard*||1/8" x 11 1/2" x 14 1/2"||1|
|Edge cap strip||pine||1/4" x 1/2" x 48"**|
|Short side||plywood||1/2" x 3 1/2" x 12"||1|
|Short side||plywood||1/2" x 3" x 12"||1|
|Long side||plywood||1/2" x 15" x 3 1/2"||2|
|Light fixture||General Electric Co. Model # 27270|
|* white one side|
* Length indicates grain direction