How to Build a Wood Projector
If you want to enlarge slides so that they appear in focus on a wall or screen, you need a projector. Traditional projectors, however, are expensive. You can build your own projector at home with some wood, a couple of lenses and a flashlight. This project can be completed by anyone with some basic woodworking skills and an attention to detail.
Things You'll Need
- Flashlight
- Sheet of plywood
- Electric saw
- Electric drill
- Cable ties
- Sharp knife
- Wood glue
- Concave lens, the same diameter as the flashlight lens
- Convex lens, the same diameter as the flashlight lens
Instructions
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1
Remove the lens from the flashlight. Depending on the model, you may have to break the lens to get it out. Since you won't need this lens to build your projector, you can break it if you have to.
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2
Cut a square piece of plywood 12 inches by 12 inches. Lay the flashlight on this square so it is centered on the wood. It should be pointed toward whichever edge you consider to be the front of the projector. It doesn't really matter which edge you choose. Drill two holes on either side of the flashlight and thread cable ties through the holes to hold the flashlight in place.
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3
Turn the flashlight on and ensure the flashlight is parallel to the plywood to which it's fastened. The beam of light should not shine at an angle to the wood. You may have to cut a few thin pieces of wood with the knife and glue them into place under the flashlight to keep it in position.
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4
Cut two small pieces of plywood to serve as posts for the convex and concave lenses. The posts will secure the lenses in place. These should be 1/4-inch high, twice as wide as the lenses and as long as the diameter of the lenses. If the lenses are different widths, you'll need to cut posts of different widths. Use the knife to cut a groove down the center of each post. Do this by laying the blade of the knife across the post where you want the groove to be and saw back and forth, applying gentle pressure. This will remove small amounts of wood at a time, allowing you to control the width and depth of the groove. The groove should be the width of the lens that the post is for. Glue each lens into its groove.
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Place the concave lens (curves inward, thinner in the middle) in front of the flashlight at the very edge of the square of plywood. Place the convex lens between the flashlight and the concave lens. The beam of light should shine directly through both lenses. Do not secure the lenses in place yet.
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6
Cut another post to hold a slide (transparent photo) in place. This post should be similar in size to the posts for the lenses. Carve a groove down the center of the post that is just large enough to hold a slide in place without having to glue it. This groove should be carved in the same manner as the grooves for the lenses, but not quite as wide. Place a slide into the groove.
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7
Place the slide between the flashlight and the first lens. Move the projector to about 20 feet away from the wall or screen. Adjust the positions of both lenses and the slide until the image comes into focus. Try to get the image as clear as you can. Experiment with the distance between the screen and the projector as well to focus the image.
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8
Glue all three posts in place, securing the lenses and the slide. Make sure the slide can still be removed easily to allow for different slides to be inserted. Use a permanent marker to write the distance from the projector to the screen onto the plywood base of the projector. This will help you remember where to place your projector when in use.
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Tips & Warnings
You may have to adjust the distance from the projector to the screen for certain slides.
References
- "How to Build Slide Projectors"; N. W Edmund; 1968
- Photo Credit Jupiterimages/liquidlibrary/Getty Images
