How to build a Light Table

Did you ever want a low cost way to view a whole bunch of negatives or transparencies at one time, or did you want to be able to look at a whole roll of film at one time? If you did then a Light Table is what you need.

Click to enlarge
Light Table with images

Light table with a sheet of Slides, a 4X5 Transparency, and a sheet of Color Negatives

The cost of this simple Light Table is less than $50 in materials. To Build this Light Table  requires some skill with carpentry tools and a little skill in electric wiring.

The Materials:
One 1X4 - 6ft board (I used pine)
One piece of 3/4 inch plywood 11 1/2 inches X 21 1/2 inches  (I used what I had in stock)
Two 18 inch length Undercabinet Fluorescent light fixtures. ( LightsofAmerica  or GE Basic)
One 18 gauge extension cord 6 ft minimum. (I used a 9 foot cord) 
One heavy duty cord switch. Picture
White ACRYLITE FF sheet (PDF 4MB) 1/8 inch (3mm) thick 11 1/2 inches X 21 1/2 inches
10 #6 1/2 inch Flat head wood screws (Philips head).
Screws to mount the Undercabinet light fixtures.(4) 
1 1/2 inch Drywall screws 

Tools:
9/64 inch high speed drill bit
7/64 inch high speed drill bit
1 1/8 inch flat wood bit
Countersink
Drill motor
Circular Saw to cut wood and plastic (a sharp Carbide tipped, fine tooth blade is recommended for cutting plastic)
Philips Screwdriver to fit screw heads
Staple gun with 1/2 inch staples

The most important part is the plastic sheet that diffuses the light and gives a table to put the film onto.
The Plastic sheet is called ACRYLITE FF and is used by Sign Manufactures.  I bought a 1/8 inch thick 18 X 24 inch cut piece for $14 in 2000 from a local sign company.

Acrylite FF Plastic Sheet

Acrylite FF Plastic top

Plastic top with a scrap of the original sheet showing the peel-off protective cover.

Acrylite FF Plastic top

Inside View

LightTableDrawing.gif (4000 bytes)

Inside view with top removed

Click for large drawing of the frame layout

To build the frame or the sides of the Light table, cut two 1X4's to 20 inches and two 1X4's to 11 1/2 inches.
Using two drywall screws at each joint, place the 11 1/2 inch boards on the ends of the 20 inch boards. Cut a piece of 3/4 inch plywood to 11 1/2 inches X 21 1/2 inches. Using drywall screws, mount the plywood on the bottom of the board frame.

Drill a 1 1/8 inch hole in the middle of one end of the board frame for the extension cord to come through. (see Inside view) Make the hole large enough for the receptacle end of the extension cord to go through so that you don't have to cut the cord. That hole also works as a vent. Those lamps get warm!

Remove the plastic diffuser from each lamp. Discard the diffusers. Temporarily remove the fluorescent tubes and mount the lamps to the plywood bottom. Place the lamps so that the lamp tubes are near the center of the box. Leave space between the tubes. See Inside View.  Replace the tubes, turn on both fixtures, test the lamps. Leave the lamps turned on! Wire the heavy duty cord switch at a convenient place on the cord. (Tip: cut only one wire Picture). Staple the wires to the plywood bottom.

Work with the plastic, flat on a backing surface. DO NOT remove the paper from the ACRYLITE FF. Mark a line 3/8 inch from all edges.  Drill the ACRYLITE FF with a 9/64 inch high speed drill bit. Using the line for center, drill four holes at the intersection of the four lines (corners). Drill the rest of the holes spaced at equal distances.  Be gentle, that is fragile plastic and will split if too much force.  Drill two more holes on the long sides and one hole in the middle of the short sides for a total of ten holes. See the Light Table with Images and see Acrylite FF Plastic top for placement.

Countersink the holes so that the flat head screws are flush with the top surface. Position the drilled and countersunk top on the wood frame. Drill a 7/64 inch pilot hole 1/2 inch deep through  the ACRYLITE FF mounting holes into the top of the board frame. Peel off the paper cover on both sides. Mount with #6 1/2 inch long flat head screws.  Do not over tighten the screws.

Enjoy!

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Last Edit: May 16, 2009