Wednesday, October 21, 2009

Homemade light box with fluorescent lights (very fancy)

In this post, I provide a tutorial for building a light box that works just as well as the fancy expensive ones you can buy at art supply stores, but for less than half the price. Like this:



For a long time, I'd been wanting a light box to use for tracing artwork. They come in handy in a variety of situations, but in particular I'd been wanting to trace images using fabric markers onto t-shirts. After looking at prices for a really nice one, I decided to see if I could make one myself. I found some good tutorials, but they used regular incandescent bulbs, which don't distribute the light well across the tracing surface, and also heat up, which can be a problem. (Of course I could substitute CFC's to solve the heat problem, but I'd still have uneven lighting.) It seemed like the fancy expensive boxes all used long, tube-shaped fluorescent bulbs, so that's what I decided to use.

This tutorial starts with some background about my approach to the project, then a list and descriptions of the materials, and then detailed instructions on how I put the thing together. Enjoy!

BACKGROUND:

(skip to: Materials, Instructions)

Having decided on fluorescent lights, I had to do some research on how to wire them, because you can't just hook them up to a simple socket the way you do a standard incandescent. (I also had to learn how to spell fluorescent to be able to write this post!) First I considered buying a pre-made fluorescent fixture, like a shop light or an under-cabinet light. But, for the size of box I wanted, I needed a two-bulb fixture, which was too much money for a DIY project (might as well just save up for the whole light box!). Also I wouldn't get to arrange the bulbs to the optimum distance apart to provide even lighting across the surface. I considered buying two single-bulb fixtures and wiring them in series, but for all that money and trouble, I should really be doing it from scratch. So I asked around at my local hardware store, and found that there is a little box called a ballast that has to be wired in to any fixture using a fluorescent bulb. You connect the ballast to a couple of special little posts which hold the bulb from both ends, and plug it into a power source, and you've got a broad strip of nice, even light!

The next key element I needed was something to diffuse the light at the surface. The hardware store had these large sheets of semi-opaque white plastic that seemed to be the perfect thing. I think they were intended for those types of ceilings where there are sound-dampening ceiling tiles in a grid, and some of the grid spaces are fluorescent lights. I just needed a small square of it. They gave me a huge sheet that had one side broken off, for free. Awesome!

I decided to make the box 11x14"– about the right size for a t-shirt design, and also a standard size for glass, which I needed for the top! I experimented with how far away the bulbs needed to be from the diffusing material, and determined I needed a depth of about 3.5 inches. I could have gone slimmer, but the tradeoff would be less-diffused light, or two strips of bright light, one above each bulb.

MATERIALS:

(skip to: Background, Instructions)

Here's what you need to build a light box exactly like mine. Items with *'s are explained in further detail below. You can make tweaks to sizes or experiment with other materials if you like! Also, this stuff is all easy to work with, so don't be intimidated if you haven't used something before.



Various pieces of wood*
Glass – 1/8" thick, two pieces, 11"x14" each
Light-diffusing material – one piece, 11"x14*
Wood glue
Cord switch*
Small wood screws – #6 at 5/8"
Picture hangers*
Mounting brackets*
Nails – 1-1/2" and 5/8"
Small wire nuts*
Fluorescent bulbs – two 12" 8-watt
A household extension cord
Two ballasts*
Hammer
Drill
Paintbrush
Varnish (I use polyurethane)
Staple gun (not pictured)
Now for some further detail. Email me or comment if you still have questions!

The wood you need is as follows:1/4" plywood – one piece @ 11-1/2"x15", two pieces @ 3-1/2"x15"1x2 board – one length @ 14"
Flat 1" molding, 1/4" thick – two lengths @ 14"
1/2"x4" board – two lengths of 11"

Remember that, for whatever, reason the actual sizes of lumber are always 1/4" to 1/2" smaller than the size it is called. So your 1/2"x4" is really only 3-1/2" wide, and the 1x2 is really only 3/4"x1-1/2".

I described the light-diffusing material I used in the intro, but you can use any semi-opaque white plastic sheeting, fabric, or other material as long as it scatters the light. In case you're curious, here's a shot of the label that was on the plastic I used:

The cord switch is optional, or you can cannibalize a broken lamp with a good cord that has a switch in it already.

The picture hangers are repurposed as brackets to hold the glass on top, so it can really be any metal thing that does the trick.

The metal mounting brackets would be found probably in the electrical section of the hardware store, with the conduits etc.

Wire nuts are really simple little doo-dads for connecting two wires together – you just strip the insulation of the ends of both wires, hold the bare ends together both facing the same direction, and screw the nut over the ends, making sure to cover the entire length of exposed metal.

The ballasts will be in the lighting section – just ask for ones that will work with 8-watt bulbs. You might find one that has connectors for two bulbs. I bought two single-bulb ones, and they came with the posts you insert the bulb into. You may have to buy the posts separately and use more wire nuts to connect them to the ballasts.


INSTRUCTIONS:

(skip to: Background, Materials)

This project happens in three phases:
1. building the wooden casing,
2. creating the inner electrical component, and
3. assembling the casing, electronics, and tracing surface all together.

Phase one, building the casing:

Begin by assembling the four sides together. The 11" lengths of 1/2"x4" will be the short sides, and the two long pieces of 1/4" plywood with be the long sides. The long sides will be attached on the outside, nailed to the ends of the short sides. However, before you attach them, you will need to fix the molding on the long sides. These pieces will become ledges for the glass to sit on, so they need to end up on the inside of the box just a tad down from the top. This way the glass will sit flush with the top of the box. By making a few marks on the long sides, you can determine exactly where the molding will go.

Lay one of the short sides down, and hold one of the long sides upright against the end of it. Make a mark on the face of the long side where the two pieces intersect. Do the same thing on the other end of the same face, and repeat with the other long side board.



You should have four marks, roughly 1/2" in from each end. We know the molding needs to fit between these lines.



Next you'll determine how far from the edge to put the molding. The glass will be layered with the light-diffusing material in between, so you need to account for that entire thickness:



Lay this glass-plastic sandwich down, and hold the long side up against it with the marked side facing the glass.



This time, rather than risk the inaccuracies of marking the thickness (we want to be sure the glass sits exactly flush), you'll go ahead and glue the molding on where it goes. Lay down a thin strip of glue on the molding.



Stick it to the face of the long side, touching the glass. Be sure that it falls between the two marks. Clamp it or hold it for a few minutes until it's somewhat set so it doesn't slip out of place.



Do the same with the other board.



Now that you have the placement exact, fix the molding more permenantly. I used a staple-gun because the molding was so thin, but if yours is thicker you might use some short nails.



Now you can put the box together. First glue and then nail the ends of the short sides to the long sides where you have them marked.



You may need a block or a thick book to prop up the sides at 90ยบ while you nail them.



You should now have a rectangle, with the molding on the inside.



Glue and nail the 11-1/2"x15" board to the back (the side furthest from the molding), and you'll have completed the casing!



Phase two, creating the inner electrical component:

All the lighting components will be attached to the remaining 1x2 stick of wood, which will then be inserted into the casing. The bulbs will be mounted along the sides of the 1x2, facing outward, and the ballasts will lay across the top.

First you need to mark where the posts to hold the bulbs will attach. To determine their distance apart, go ahead and insert a bulb between two of the posts from the same ballast. (If you had to buy the posts separately, just pick two and you can connect them to the same ballast later.)



Hold this setup along one of the narrow edges of the board. Trace around the posts where they will be attached.



The ballasts will lay across one of the 2" faces of the insert. The mounting brackets will need to be bent downwards to fit around the board and attach on the sides, since the board is about as narrow as the ballasts themselves.



Attach the ballasts using the mounting brackets, nailing them to the sides of the board. Be careful not to put a mounting bracket over where you traced the posts.



Take the bulbs out of the posts and nail the posts into place, completing your insert.



Phase three, assembling the lightbox:

First prepare the extension cord. If you are installing a switch, follow the directions on the package.



Then cut off the end of the cord that has the socket (leave the end with the plug attached). Drill a hole in one corner of the box and insert the cut end of the wire.



Next, separate the two wires of the extension cord at the end, and strip about 1/4" of the insulation off of each. Notice that one side has smooth insulation, and the other side is ribbed.



Now you hook up the lighting components to the power cord. Make sure the insulation is stripped at the ends of all the wires coming off the ballast. You can set the lighting insert inside the box, but hook everything up and test it before attaching the insert to the box, in case you need to take it out and fix any problems.

Find each ballast's white wire, and gather them together with the wire from the ribbed side of the power cord.



Secure the three ends with a single wire nut. (Just twist the ends together and twist the wire nut onto them until they are attached and there is no exposed metal.) Use another wire nut to connect the black wires to the smooth side of the power cord. If they aren't attached already, connect the posts to the ballasts, being sure the two posts for each ballast are on the same side.

Now's a good time to put the bulbs in, plug in the cord, and see that the lights come one. Be careful! Make sure the entire length of every wire is covered with either insulation or the wire nuts. And don't do anything stupid that would get you electrocuted. (The bath tub is not the best place for this activity, for example.)



If all is well, screw the insert to the casing. You'll want the insert to float about a half-inch from the bottom of the box, so set a thin paperback or something in the bottom of the box to hold it up while you . Center the insert, and measure how far down it is from the top of the box. At that distance plus 1/4" down on the outside of the box, drill a couple of pilot holes through the sides. Make sure the holes line up with the ends of the insert, and screw it in. Remove what you had in the box holding it up, and the insert should stay. If it's not totally secure, remeasure and do it again.



The last step is to put the glass on top. Lay your triple-layer, glass-diffuser-glass sandwich down on the top of the box, and settle each layer in so they rest on the molding. The top glass should be flush with top of the box. We'll use the picture hangers to hold the glass in.

Straighten the picture hangers into an L-shape.



Using a scrap of wood underneath, drill a small hole in each one.



Nail them to the box, with the bent end positioned over the glass. Add some staples to keep them in place.



And that's it!


6 comments:

  1. The finished product is so pretty it could be used as home lighting!

    ReplyDelete
  2. find the home products to design your home.
    Thanks

    kronleuchter

    'very nice post'

    ReplyDelete
  3. I think I might use a dado joint instead of brackets to slide the glass in... what do you think?

    ReplyDelete
  4. @im only just me: I think that would look very nice. Could you do that in a way that the glass would still be flush with the top of the box, though? I can just imagine that when I'm tracing something, I'd get irritated if there was a lip around the edge... especially if the paper is bigger and wants to hang over the edge... Let me know if you figure it out!

    ReplyDelete
  5. How much did the materials cost in all?

    ReplyDelete