Help with lighting windows

ENT2151 · Post by **ENT2151** » Fri Mar 30, 2007 4:27 pm

Hello, recently i had begun working on a lighting plan for the Revell kit of the Republic Venator model. as i was doing so, i came across some windows that i dont know how i would light. to start with, something has to be removed, should it be just small parts and feed round fiber optics in, or should the entire thing be removed. If so, what would i replace it with to get the feel of multiple windows? also, once that is taken care of, what would i use as the light source, a single LED wont work. here are some pics to help show what im talking about.

http://i145.photobucket.com/albums/r206 ... tlined.jpg
Windows outlined so you can see which ones i mean
http://i145.photobucket.com/albums/r206 ... C00214.jpg
same pic, but without the outlines for a better view

any help is apreciated, thanks.

Sparky · Post by **Sparky** » Fri Mar 30, 2007 4:47 pm

The short answer is get the part molded and clear cast.

Or make a clearcast insert which is all the windows, so one removes all material from that area then cements in the clearcast piece and fills the gaps with the black AVES (the Fixet stuff), or black CA.

Once you have a clear cast piece you can workout how many LEDs will be needed to fill all windows evenly, or go with a bright light in the middle of the model to fill all the windows.

If you can design an insert that connects all the windows say, a plate with the window inserts positioned correctly, then you can clearcast is as a light pipe and once again use a small number of LEDs, or an LED array to evenly illuminate all the windows.

It will require getting the part copied so you don't have to trash the original kit piece, then carefully cutting out all the window blocks to use as masters for your insert, maybe milling them out of the hull.

Then building the plate and connecting it to the backs of the windows. If you make them all straight pieces or only slightly angled, and the back plate is square/flat, you can cast this open face style mold.

To post cure the clearcast stuff from smoothon I used a crock-pot with a slab of marble floor tile sitting on the top:
http://www.kc6sye.com/images/images_03_ ... _cstng.jpg

ENT2151 · Post by **ENT2151** » Fri Mar 30, 2007 4:53 pm

Brilliant idea, i actually started to think about casting it in a clear form, and then blocking out the other areas. i think that would work, but i still need a light source for it then. also to add tot he question, i was calculating the number of fiberoptic wires needed for the other windows and came up with 115 @ 1mm DIA, and 313 @ 0.5mm DIA. how would you suggest to actually light those, keeping in mind that the model is large on the inside, so a single light wouldnt work, plus i wanted them to turn out fairly bright, and not dim. though dim might be better. what do you suggest?

Sparky · Post by **Sparky** » Fri Mar 30, 2007 5:00 pm

Multiple bundles to multiple LEDs, might be the best way.

If you get fancy you can divide up the fibers from the windows and select the LED they go to strategically:
So that, say, (approximately) every other window will light up with a different LED, then a switch or programmed time (you use microcontrollers) will cause different windows to come on and go off. The night shift comes on duty and the day shift goes off.

For larger window sections which appear to be hall ways, you can expect them to stay light all the time.

Use black heat shrink, and black pvc tubing to help shield each LED's output from adjancent bundles. the heat shrink would be used to hold the bundle to the LED, have you seen an example of this yet?

ENT2151 · Post by **ENT2151** » Fri Mar 30, 2007 5:06 pm

yes, someone else had reccomended that to me, but i wasnt sure if it would work. is there an LEd that you recommend? it just needs to be white lights, and nothing more, though they should probably be more towards the yellow tint, than the blue, unless they are pure or close to pure white.

Sparky · Post by **Sparky** » Fri Mar 30, 2007 10:21 pm

Just get them from a reputable supply house like digikey or mouser or someplace that provide the actual data sheets for the LED. They will usually give you a color rating on the light produced, also called temperature.

You are more likely to get LEDs that all look the same when buying a specific LED from an electronics house. If it has a data sheet with all the curves and electrical characteristics you can be more confident that each time you buy a batch they will look the same.

Most of the regular LEDs not the ones you get from stripping a Christmas light string, have a lip at the bottom of the LED (these are PCB mount style or leaded style). You want these since this gives the heat shrink something to cup around. Helps prevent the tube from pulling free.

I had issues with epoxy turning yellow on me and not fully setting up, this the five minute kind that you squeeze out and mix by hand. Not sure If I had a bad batch or mixed to little an amount but a lot of my fiber to led joint broke free, even with the heat shrink helping keep the epoxy in place while it cured.

http://www.kc6sye.com/images/images_04_ ... bblies.jpg

As you can see the heat shrink couldn't shrink far enough to capture a single fiber.

The problem with this was that these pieces were installed in a tight place, and the brass tube was being coated with epoxy to bond it in, so when the fibers broke I couldn't easily repair the joint. I've heard CA makes the fiber brittle, but it can't be worse than epoxy just crumbling away or adding a yellow tint.

Also you will want flat faced LEDs if you can find them, they are less common so you selection of manufactures and thus color ratings/tints will be smaller. In the end we sanded the ones we got, and polished them with automotive fine grit sand paper, 2000 I think it is.

Sparky · Post by **Sparky** » Fri Mar 30, 2007 10:25 pm

I thought I had another image of the bundled fiber optics and some heat shrink. . .
http://www.kc6sye.com/images/images_04_ ... _bndle.jpg

Here they are:
http://www.kc6sye.com/techmages_4_21_04.html

Madman Lighting · Post by **Madman Lighting** » Sun Apr 01, 2007 5:38 pm

I use SuperBrightLEDs.com for all my LEDs. They supply some very bright white LEDs, 18,000 mcd for not too much money.

I've tried to buy very bright LEDs from D-K and mouser and they never have what I really want. Plenty of small ones, any kind of thing you would use in high volumes, but not the specialty stuff.

Of course, I'll sell you some LED/fiber optic kits if you want.

Sparky · Post by **Sparky** » Mon Apr 02, 2007 4:40 am

When ordering form other sources the issue is with consistence:
if they don't post a regular manufacture's spec sheet, that means, current useage, voltage requirments, lifetime, and mostly color wavelegnth are all fuzzy. That means in a batch you may get visibly different colors and brightnesses.

Balok · Post by **Balok** » Sun Jun 10, 2007 12:31 am

I've noticed that. Its quite annoying.

Sparky · Post by **Sparky** » Sun Jun 10, 2007 1:19 am

I'm still working on the Tower! I will absolutely get the last bit of RTV on the top of the tower, then it's ready to be flipped.

Bar got my first cast of the bridge sticks and launch bays. Please check with him on shrinkage.

The trick is to get their slow set stuff and post bake it. It heat cures so a post backing will speed it all up.