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