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Acrylic Hood and Support design help needed

Mortis

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Joined
17 Jun 2009
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410
I'm making a new Led lighting unit for my tank. The LEDs are pasted on 3 4x1inch and 29 inches long aluminium box pipes. Each array will have its driver fitted on the back of the pipe. I am making a 30x18x6 inch box out of 8mm acrylic. This would be the same footprint as my tank and the 6 inch height is enough for my lenses + led + heatsink + driver + fan.
I had an idea to mount the arrays that I wanted to run by you guys to see if it would work.
I plan on making a couple of slots almost end to end along both sided and using an L shaped piece of 12mm acrylic to slot in from the outside through the hood and into the centre of the pipe to hang each array. This would allow give me the flexibility to slide each array a bit forwards or backwards so that I can increase or decrease the amount of light in some areas of my tank.
Would this design work out in terms of having the strength to support the lighting unit ? There will be no bottom plate to the box

My second question is on designing support legs for the lighting unit as I cannot suspend the light unit from the ceiling or from the wall or add bars to the sides of the cabinet.
The light unit will be around 8-12 inched above the rim of the tank. Final height will be confirmed after checking out the spread. I was thinking of having a leg on each size 8 inches wide s that I have place for my filter pipes etc to go in. The strip will be made of 12mm acrylic and have a u shaped piece at either end that goes on the sides of the hood and side of the tank. Will it support the weight or should I use 2x12mm strips of acrylic. I'm also concerned that it might topple over. Would it work or am I being paranoid.
If anyone has made something similar can I see pics of your design ?
 
Are you using clear or coloured acrylic? I've had no fun with it as far as lights/ tanks are concerned with warping.:(
 
IMG_20140306_205354_zpse64bb5df.jpg
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http://i1342.photobucket.com/albums/o779/mortisn/IMG_20140306_205354_zpse64bb5df.jpg

Thats the basic design. I hope you guys can understand my shady drawing :D

The hood will be made with Black acrylic while the supports will bemade in clear
 
lol :thumbup: :lol:

Can you not build like a shelf inside the hood either end to sit the bars on? Just an extra strip of 12mm should do it. As long as the bars are cut exact, there will be no chance of them twisting and potentially falling.

What's the reasoning for doing a separate support, instead of just making the hood taller and why in clear?
 
I thought I'd get in on this dodgy diagram malarkey :D

This is what I meant with the shelf. This is inside each end. Obviously I've added a few more so you can adjust the height. Also an end stop so you don't accidentally push one off the end and into the tank. The gap at the end just needs to be big enough so it fits the width of the bar so it can be moved between levels.

Should be a lot simpler then cutting slots in the side and will tidy the outside up obviously, as there will be nothing out side to see.
image_zps2eb6c96f.jpg
 
I could do that but having the Ls and the slot allows me to slide each bar forwards and backwards giving me the ability to increase or decrease light in a certain part of the tank, for example if I had a sand FG without plants in it. I was just wondering if it would hold up. What do you think of the support leg design ?
 
You can still slide it on the "shelves" just like with your design, just that you don't see anything from the outside. Plus the ability to raise and lower each or all the lights.

I don't really understand what the supporting piece is for, when you can just do that to the hood itself.
 
Nevermind, I've clicked on. Its more a luminaire than a hood. I thought the clear perspex went all the way around, which is why I couldn't understand why you didn't just make the hood deeper :D

Side to side movement could be pretty harsh. 4 L shaped supports on each corner would combat this.
 
Aah I got your shelf design now. Just a1-2 inch strip along the sides and then shove the ALU pipe on top of it so that it rests on it. Then I will still be able to slide it back and forth. How would I raise and lower it ? By removing the shelf and sticking it back again ?
I didn't understand the L shaped support bit though. Can I have another shady diagram please ? :D
I wanted a support that rests on the middle of the sides of the tank because I need 3-4 inches from each corner for filter pipes, diffuser tubing etc
 
I might be able to offer you a bit of advice as my job is designing acrylic displays. Unfortunately I can't see your drawing because the link is being blocked by our software at work and I can't make head nor tail of your description :). Can you post your drawing again?
 
Yes that's it, but the shelves would only need to be about 1/2 inch thick, if that. The shelves are all pre glued in. Depending on the height of the hood will depend on how many you can get in but no, there's no re gluing shelves etc. the best way I can describe it off the top of my head is like oven shelves :D The supports are there all the time, the shelf, or in your case, the bar, just gets placed where ever you want them. The gap at the end between the end stop and back of the hood is so you can change between levels.

If you need the corners free then my support idea wouldn't work, so I'll not go any further with that. If I think of anything else, I'll be back with a diagram :lol:

@James D - This is the diagram:

IMG_20140306_205354_zpse64bb5df.jpg
 
Cheers for that!

I'm curious as to why you want to make a tank-size 'hood' and then have it hovering 10" above the tank, is it just to hide all the light fittings etc?

My first thought though is about the weight of the thing, an acrylic box that size in 8mm is going to be very heavy, especially with all the lighting equipment in it.
 
I made it bigger because I have used a lot more LEDs as I wanted to add some various colour spectrum ones because IMO the 6500K ones dont have good CRI and fish and plants dont pop. So large hood size is to distribute them well in order to get good coverage and colour blending and also so that I can actualy use this on a larger tank if I upgrade with just a lens swap :D
Ill be using a dimmer to run the LEDs at below 50% power and if the thing runs cool then I wont need fans and the hood height will be lesser.
The hood will actually be anywhere between 6-12 inches above the tank actually. The final height will be determined after checking out the light spread and intensity.
Overall the innards of the lighting system will be quite light, most likely less than 2 kilos. Would say 6mm acrylic be sufficient then ? Id also appreciate it if you could suggest a few support designs as well please

NC 10 thanks for the oven shelf explanation. I dont think multiple shelf heights would be required as such.
 
I think 6mm should be enough, I'm sure 8mm will be too heavy.

Personally I'd still be reluctant to have something like that resting on the glass of my tank though, is there nowhere else you can support it?
 
Unfortunately not. I don't think it should be a problem. It will be similar in weight to a regular hood/canopy.
I'll add another support in the back middle
 
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