Light table question

[GrandpaPhil]

If you are going to convert a table to a light table, how thick does the acrylic sheet need to be to prevent flexing while drawing?

 

I am going to frame in the top of the table in my model room with 2x4’s, put LED stick lights inside and then close it in with a hinged 4’ x 8’ sheet of acrylic, but I am debating between a 1/4” thick and an 1/8” thick.

[mtaylor]

I'd think the 1/8" is pretty flimsy for something that large at 4X8.    Best bet may be to go to the supplier (hopefully local) and see.   I have a feeling you might need something thicker than 1/ 4" as you will be leaning on it.  Back in the day, ours had glass (1/4" or 3/16") for the large tables.  

[GrandpaPhil]

Thank you very much for the information!

[GGibson]

Will be interested in seeing a picture of this table when you are done, Phil! 👍

[kgstakes]

If you can find 3/8 or 1/2 clear acrylic, that would be best.  Would not use 1/8 inch, too weak unless braced allot which kind of defeats the purpose of a "shadow free" work area.

 

1/4 acrylic will work but then again, I would brace it pretty good.  I worked at a place where we use acrylic to cut out signs etc. and the thicker you can get it the better.  Also, be careful with the sheet, it may seem stable, but it does break, chip, easy ( 1/8 or 1/4 ) if handled roughly, until set in place.  

 

Nice idea and interested in seeing the finished table.  

[modeller_masa]

I'm not sure my design will work, but I like the light table idea. 

[Roger Pellett]

My light table is approximately 48in x 30in.  It is made from 1in (nominal) lumberyard pine.  The top edge of the pine box is routed to form a 1/2in wide x 1/4in deep rabbet. It is lit by several 1tube fluorescent light fixtures.

 

The top is a piece of double strength (approximately 1/4in) plate glass.  This is plenty strong, doesn’t deflect, doesn’t scratch, and doesn’t require internal bracing. It sits in the rabbit.  If I were building another one I would again use plate glass not acrylic.  

 

Roger

[tmj]

Roger,

How do you 'diffuse' the light so that you do not have bright "HOT-SPOTS" where the lights are mounted? 

I tried making one of these for a gal at work and could never get the light the way we wanted it. If I mounted the lights around the perimeter of the box, with a wide border to hide the lights, the face of the box would be brightest around the outside of the 'window', getting darker as you moved towards the center. If I put the lights in the middle of the window It looked like a box full of light sabers through the diffusion material. Even tried LED strips for a more subtle effect, but still no go. No matter what I tried, I could always see where the lights were. I never achieved a smooth, uniform lighting effect.   

[Snug Harbor Johnny]

  I happened to stop by a Barnes & Noble today and saw an LED flat screen light 'table' for $19.99 ... Now the glowing surface is only just over 8 1/2" x 11". but I figure for larger tracings, the two sheets can be 'tacked' together at the corners with temporary artists' "spray mount" - a product made with a milers grip so the item(s) can be repositioned as needed.  Then I can just move the sheets over the led lit area a section at a time.

[mtaylor]

1 hour ago, tmj said:

Roger,

How do you 'diffuse' the light so that you do not have bright "HOT-SPOTS" where the lights are mounted? 

I tried making one of these for a gal at work and could never get the light the way we wanted it. If I mounted the lights around the perimeter of the box, with a wide border to hide the lights, the face of the box would be brightest around the outside of the 'window', getting darker as you moved towards the center. If I put the lights in the middle of the window It looked like a box full of light sabers through the diffusion material. Even tried LED strips for a more subtle effect, but still no go. No matter what I tried, I could always see where the lights were. I never achieved a smooth, uniform lighting effect.   

The "diffusing" is a problem.   Way back in the day, the "best" one I saw had the lamps (florescent as I recall) under shades around the edges that shined on a white board about 6" from the glass.  Also, the glass was frosted on the "light bulb" side.  Ours were in a room that wasn't brightly lit but did have easels with lights to hang drawings, etc.

[Jaager]

LED version of fluorescent 4' light  - evenly spaced.

Cover the bottom and sides of the box with aluminum foil - heavy duty probably plays nicer - 3M spray adhesive might work to bond it

 Suspended above the LED's  =

 

Kyped from Home Depot  $16 each:

 

OPTIX
23.75 in. x 47.75 in. White Acrylic Light Panel
Acrylic lighting panels offer good light transmission
Prismatic surface helps diffuse light from a fluorescent bulb
Lightweight structure makes it easy to place and move
Acrylic lighting panels are an economical, lightweight and easy to use solution for all your fluorescent lighting cover needs. Standard sizes fit most drop-in ceiling systems as well as many standard fluorescent lighting fixtures. They can be cut fairly easily using standard handheld plastic sheet cutters to fit custom lighting fixtures. Available in multiple finishes and colors, these panels are ready for use in a variety of both commercial and residential locations including kitchen and bath fixtures, basements, office buildings, schools, garages and recreation rooms. Soften any fluorescent light fixture to create a professional looking presentation today with these acrylic light panel covers.

    Made of white, non-yellowing acrylic
    Commercial-grade suspended-ceiling light panel
    Approximately 8 sq. ft. coverage area per piece
    Prismatic surface disperses light evenly

 

Working surface should probably be tempered glass

Glass Tops Direct.
48" x 96" Rectangle Glass Top 1/2" Thick - 1" Bevel Edge With 1" Radius Corners

Save 50% Original price $1,689.90
Current price $844.95

 

 

[GGibson]

We had a light table discussion at our last local ship builders' meeting, and one member had a SanerDirect A2-sized light pad... approx. 25"x18"... 

[Roger Pellett]

I never gave it much thought to diffusion.  It seems to work well enough for my needs.

[modeller_masa]

Technically, the best light diffuser panel is the part in the LCD screen for TVs and smartphones. There is a thin LED light strip at the bottom of the display, and the thin layer emits and spreads light to the entire screen equally. It seems like the light pad has a similar structure.

 

 

The video shows how he modified a monitor into a light pad.

 

 

https://aliexpress.com/item/1005004799141286.html

I'll try this diffuser film.

 

[modeller_masa]

Lamp = LED strip

 

Diffusion plate = Laser engraved acrylic panel

https://en.kohacraft.com/archives/make-a-flat-light-emitting-lighting-by-processing-acrylic-into-a-light-guide-plate-with-a-laser-cutter.html

https://aliexpress.com/item/1005006156384485.html

 

Diffusion film = translucent PET film

https://aliexpress.com/item/1005006059186279.html

 

 

 

[GrandpaPhil]

What about just buying a glass dining room table and putting lights below it?

 

Those run about $110 from Home Depot.

Edited November 30, 2023 by GrandpaPhil

[Roger Pellett]

I looked at my light table yesterday and realized that contrary to my above post I did not use ordinary plate glass.  The top side of the glass is smooth but the under side is embossed with a diamond shaped pattern.  This acts to diffuse the light.

 

Roger

[mtaylor]

Just a couple more thoughts....   visit your local glass/window supply company.  You'll be able to see how flexible acrylic is.   Also have look what they off in glass, not acrylic.   You should also check if they have frosted acrylic or glass for light diffusion.  

 

You WILL be leaning forward and resting your arms and some body weight on this clear/frosted top along with other items so it needs to be able to resist the weight.   

[Jaager]

A license and inspection is not needed for home built furniture, but if you use a simple plate glass and some sort of accident happens and the glass breaks into obsidian sharp spear points you might wish that you had been required to use a tempered glass that shatters into harmless balls. 

[mtaylor]

17 hours ago, Jaager said:

A license and inspection is not needed for home built furniture, but if you use a simple plate glass and some sort of accident happens and the glass breaks into obsidian sharp spear points you might wish that you had been required to use a tempered glass that shatters into harmless balls. 

Excellent point, Dean.

[Roger Pellett]

I spent an hour laying on my back at the dentist’s this PM so had plenty of time to examine the fluorescent fixtures in the suspended ceilings.  The glass in my light table is exactly the same as used to filter the light.  It must have been available from glass shops as I don’t remember canabalizing a fixture.

 

Roger 

[GGibson]

17 hours ago, Roger Pellett said:

I spent an hour laying on my back at the dentist’s this PM...

 

Oh, now you're just trying to make the rest of us jealous...

 

On 11/30/2023 at 12:14 PM, Roger Pellett said:

The top side of the glass is smooth but the under side is embossed with a diamond shaped pattern.  This acts to diffuse the light...

 

This seems like the best solution, and glass shops should have these readily available...  

[Roger Pellett]

Yeah, and today the temporary crown popped off !