Has Anyone Built a Light Box?

[Iplayfarmer]

Has anyone built a light box for tracing patterns, etc.? My wife and her mother would both like one. It looks simple enough. I'll build a wooden box with a fluorescent light inside and a plexiglass top.

Here's my question... The scrap of plexiglass that I have is clear. Should I leave it clear or should I take some coarse grit sandpaper to it to help it diffuse the light better?

 

[George2615]

I would go to HD, Lowes or hardware store and get a piece of white (opaque) plexi. Same type on a light box your Dr. uses to view Xrays.

 

[aczlan]

My sister used one that was made with a glass topped end table and a florescent floodlight.
I think she taped a piece of tissue paper to the underside of the glass to diffuse the light.


Aaron Z

 

[beppington]

Here's my question... The scrap of plexiglass that I have is clear. Should I leave it clear or should I take some coarse grit sandpaper to it to help it diffuse the light better?

I definitely think you'll want it obscured. Makes the light more uniform. You can also paint the interior of it (floor & sides) bright white to more uniformly reflect the light.

Ours here at work is obscured glass. But I made the table :thumbsup: out of plywood (bottom) & 2x6 spruce side walls with 1.5" holes drilled along the sides to dissipate heat.

I used glass so we could cut stuff on it with an exacto knife. I bought the piece of glass locally. Paid about $100 for it years ago, but justified that since I built the thing myself for very little $.

You can cut a 3/4" wide by 1/8" deep groove (notch) along the top inside edges of the 2x6s so the glass sits down in that notch securely without the need for anything else to hold it.

 

[Iplayfarmer]

I definitely think you'll want it obscured. Makes the light more uniform. You can also paint the interior of it (floor & sides) bright white to more uniformly reflect the light.

Ours here at work is obscured glass. But I made the table :thumbsup: out of plywood (bottom) & 2x6 spruce side walls with 1.5" holes drilled along the sides to dissipate heat.

I used glass so we could cut stuff on it with an exacto knife. I bought the piece of glass locally. Paid about $100 for it years ago, but justified that since I built the thing myself for very little $.

You can cut a 3/4" wide by 1/8" deep groove (notch) along the top inside edges of the 2x6s so the glass sits down in that notch securely without the need for anything else to hold it.

I'm planning to make the box out of some scrap 3/4" melamine plywood. It's very white on both sides. No painting will be necessary. I've considered the dado idea to contain the plexiglass, but I'd kind of like the top to be completely flat. I was thinking I'd coutersink two screws on each of two sides of the top to keep it in place.

I may go the glass route eventually, but I already have the plexiglass left over from another project. That's why I'm using it. I suppose I could try the sandpaper trick and if that doesn't work I'll spring for a new piece of white plastic for the cover.

 

[Danno1]

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You need to sand the plexi very uniformly. Use a palm sander w a coarse grit on the underside, not the top.

The larger the distance between the light source and the top (ie. deeper box) the more uniform your light distribution will be.

You could also put a sheet of flourescent diffuser in between the sanded plexi and the light source. This would also give a more uniform light distribution.


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[beppington]

I'm planning to make the box out of some scrap 3/4" melamine plywood. It's very white on both sides. No painting will be necessary. I've considered the dado idea to contain the plexiglass, but I'd kind of like the top to be completely flat. I was thinking I'd coutersink two screws on each of two sides of the top to keep it in place.

I may go the glass route eventually, but I already have the plexiglass left over from another project. That's why I'm using it. I suppose I could try the sandpaper trick and if that doesn't work I'll spring for a new piece of white plastic for the cover.

Dado! There's the word I was lookin' for!

I wanted the entire surface flat too, so I dado'd it so the glass is exactly flat with the top edge of the 2x6. I'd like for the entire glass surface to run to all edges with no wood, but I guess I'd have had to drill holes in it, or something like that, to secure it. The way I did it works fine, though.

I would try swirling some around sandpaper around on it just like you're thinking.

 

[Pixguy]

Dado! There's the word I was lookin' for!

I wanted the entire surface flat too, so I dado'd it so the glass is exactly flat with the top edge of the 2x6. I'd like for the entire glass surface to run to all edges with no wood, but I guess I'd have had to drill holes in it, or something like that, to secure it. The way I did it works fine, though.

I would try swirling some around sandpaper around on it just like you're thinking.

I've built these in the past using an under the counter fluorescent light and just white copy paper taped from underneath the plexiglass.

 

[forgeblast]

The one I have at work is opaque. Putting two bulldog clips on top might be helpful to hold what you are working on in place.

 

[MikeFarm]

Hi

The light box I used to do tracings of cave maps had a flat glass but clear surface and under that was a white translucent mylar sheet to diffuse the light from fluorescent tubes. You will find translucent mylar sheet at specialist art/graphics supply places. As a light box gets hot inside you need a plastic that will take the heat.

Using sandpaper to roughen a clear surface will work but it will be hard to get it nice and uniform with the correct translucency.

Mike

 

[beppington]

I think using a pretty fine sandpaper is going to be needed. Seems like rough sandpaper will leave scratches that you can actually see thru your work.

 

[dmccarty]

My old film light box uses a white opaque plastic to diffuse the light. If you cannot get something similar I would be include to just use thin, light weight paper. I do not like the idea of sanding. Not sure how well the would work.

Later,
Dan

 

[Iplayfarmer]

Maybe I could just paint the underside of the plexiglass. White paint ought to work. I'd probably still have to lightly sand the plastic with some fine grit paper to get the paint to stick.

 

[kf4uda]

This says no sanding required.

Krylon: Products: Fusion for Plastic

 

[JamesHW]

Semi opaque white plexiglass is referred to as ""milk plexiglass" in my experiece. We would often use large sheets in commercial photo shoots to create seamless backgrounds that allow lighting from below (glassware and such). I've used pieces to make easy makeshift light tables for examining slides and negatives (remember them).

Since you already have a clear sheet, you might be able to get a thin sheet of the white stuff to layer on top of your thicker piece. I believe I've seen different sizes of clear and white thin plexi sold at big box hardware stores near the window section.

Painting might work, but could also look like crap.

 

[forgeblast]

Sax.com and other art places have led versions for 40.oo, you might want to search them out before spending a whole lot of money.

 

[Iplayfarmer]

Sax.com and other art places have led versions for 40.oo, you might want to search them out before spending a whole lot of money.

I already have everything leftover from other projects... Wood, light, plexiglass, etc. All I'd be into it is my time, and I like tinkering. My time is worth the pride of workmanship.

 

[beppington]

If you don't want to scratch the plexi, place like Home Depot maybe(?) sell that self-adhesive window obscuring clear stuff that you can stick on your bathroom window or front door window to obscure the view. Pretty cheap, too.

 

[Iplayfarmer]

If you don't want to scratch the plexi, place like Home Depot maybe(?) sell that self-adhesive window obscuring clear stuff that you can stick on your bathroom window or front door window to obscure the view. Pretty cheap, too.

That's a good idea.

I think for now I'm going to just use the clear stuff I have like it is. I can always paint it, coat it, or replace it later if it needs to be translucent.

 

[MossRoad]

If you have a local newspaper you might want to give them a call and see if they have any old "paste up banks" that they would be willing to get rid of. Most newspapers (that are left in business) don't use them anymore and many have them in the basement gathering dust. Just a thought.