I have this idea to take a 1/4" or 1/8": 4 X 8 or 4 X 4 sheet of something light weight but ridgid(MDF, hardboard, styrene, foam, suggestions) and cutting it in to an amorphous / free form shape. Possibly I’ll cut two sheets the same size and shape. But it would need to be cutable with a skill saw, table saw, sawzall or multi tool and paintable. Then I want to cut a strip of undetermined width to attach to the perimeter to make a box. I’m going to mount the box flush to the ceiling. I have a bunch of white micro LEDs, an Arduino and battery that I was going to use for another project that failed. I want to drill tiny holes in the bottom of the box and insert the LEDs. I’ll hide the battery, wires and Arduino inside the box. I do have a device to change the battery voltage down to what the input on the Arduino can handle so maybe I ditch the battery for a 110 wall plug.
I’m looking for suggestions on stiffening the whole structure to keep the large flat sides flat. Or a skin material that can stay rigid without the need for a skeleton. I had thought about making a thin lightweight skeleton out of something and then attaching the skin to that. Possibly making the skeleton out of extruded aluminum L or square tubing. Or thin steel (possibly too heavy). I’ve never welded before and don’t have a welder so it might have to be rivets if I do metal. I could cut thin strips of the skin material or acrylic and glue it edge on as ribbing. Any and all suggestion are welcome and thank you very much ahead of time
My first thought is to use polystyrene foam, insulation board.
I use this on my CNC to test the model before I cut the final piece.
It’s lightweight, ideal for an overhead “thing”.
I learned this about cutting this material;
The material cuts easy which is an advantage in that if it gets bound up while cutting it will just macerate the material. I have had kickbacks that are scary but did no damage.
However, it cuts so easily a mishap can suddenly put your hands in harm’s way…
Stabilize the material for cutting by sandwiching the material with stronger material. On the table saw I use a sheet of 1/4" fiberboard laid on its surface between the blade and fence.
The dust sticks electrostatically to everything’s
Use high tooth-count blades
Easy to cut; I cut it on my table and band saw. You do need to be careful when you feed it allowing it to twist can create a kickback. I have not but assume you can use hand, circular, and jigsaws.
Easy to sand. I have sanded with a belt sander and filed with hand rasp. I believe you can cut it with a hot wire. Wear breathing protection.
Easy to drill. I use Forstner bits and step drills to get a clean cut. Twist drills do not leave a clean hole. It would cut well with a hole saw. A long small diameter hole saw [for the leds] could be made from a piece of pipe.
It cuts smooth on the CNC so I assume you can shape it with a router. I have never done it because routing something this flimsy freehand gives me the creeps. With proper & safe work holding it should be possible.
It can be painted with water-based and acrylics paints. I have tried solvent-based rattle can paint but it only works with light coats, otherwise, it melts, didn’t like the results.
It can be glued together and materials can be glued to it.
Glues include: [@Ned what would you recommend?]
PVA, the joints have to be clamped until the glue is dry
Cyanoacrylates – Cyanoacrylates bond well to polystyrene. Use only enough adhesive to cover the joint, then assemble as soon as practical. For best appearance use a low odor grade.
Two-component epoxies bond well to polystyrene.
UV Curable – UV Curable adhesives are an excellent choice for bonding polystyrene.
The LEDs could be glued in with silicone caulk. I use this stuff* everywhere and seems to stick to everything: https://amzn.to/2QeN4dQ
Never tried it on polystyrene.
*As an Amazon Affiliate, I earn from qualifying purchases.
I had the same first thought and was debating recommending EPS myself for many of the same reasons. It’s available in 4’ x 8’ sheets and various thicknesses. Easy to hollow out the back/top to hold electronics. You could cut it a bit oversize with a jigsaw, then use hot wire for a durable finished edge.
However, my concern is heat. Is this running in free air or held against a ceiling? Are the electronics central enough to use a low-temperature thermal cut-off? Also, LED lifetime is diminished by heat, so if you bury LEDs in a thermal insulation you will probably substantially reduce their lifetime unless you also include appropriate heat sinking to keep them cool.
An interesting point ref: led reliability when enclosed.
Certainly when encapsulated the junction temperature will be higher and life is lowered.
I never payed attention to that possibility when placing LED’s in their holders.and never had problems?
In fact led’s are fully encapsulated in most of the mounting arrangements I have used.
I get the problem with led bulbs and strips.
I had to pay attention to such when I installed the led strips around my house.
In those applications the chip is not usually enclosed and they are running relativelly high currents.
Its single indicators used in panels I wonder about. They are molded in plastic how does that allow much heat dissipation? Do they die prematurely?
Those are so much lower in power… A red indicator LED with 2V forward voltage drop might pull 20mA. 20mA @ 2V is 40mW, which doesn’t take much to dissipate, and in many applications it’s connected to a circuit board and I think sinks most of its heat out the legs into the board.
So the question, I think, is whether the white micro LEDs are the ~150mW bright white indicator LEDs (just use thick enough wire to be a heat sink?) or are higher power. @raidengl do you have any specs or description of the white LEDs you want to use?
Thanks everyone for the responses they are great. As for the LEDs I bought them back around 2015 for another project that ended up not happening. So they’ve never run for long periods of time. As for the specs they are micro LEDs but that’s all I remember. I’ll have to try and remember where I bought them from and see if they still have my order info. I think it was Digikey.
This is getting mounted to the ceiling in my daughters bedroom which has standard 8 foot ceilings. As such I don’t want it hanging down too far. She’s only 2 so not very tall but still. I think attaching it directly to the ceiling could lead to heat issues. So maybe putting standoffs between the box and ceiling would help with that. I can also drill some vent holes in the top. I already have the program for the Arduino graciously provided by an expert years ago. When it’s running the lights will twinkle on and off in a way that I couldn’t find in Christmas string lights. The big decision is, what color to paint the box? Do I match the ceiling color? Or paint it black (wife might kill me not sure)?
Ahhh, this is to twinkle not to be the main light for the room! This makes more sense now. If I were doing it I’d make standoffs to hold it about ½" away from the ceiling, not only for heat, but also because ceilings are often not quite as flat as they look, and any disagreement about what “flat” means between your cloud and the ceiling would be accentuated if they were close together.
If you make it black you’ll have to add lightning to it too!
I use the term Cloud more as a descriptive term for its shape then the theme. I was thinking more of a stars in the night sky theme. My wife is in commercial design and “clouds” are the new in thing in commercial ceiling spaces.
sorry @raidengl l I did not know you worked at HD…
editorial:
Just so you know I shopped exclusively at HD for 20+ years or so.
Then;
they would not provide a discount for veterans except on veterans day, Lowes honored it every day
then HD allowed the veterans discount but made it hard to get and use, yet not all stores honored it
now HD has made it easier to use (pro account) and get but they still do not allow discounts on many items. Lowes only restricts sale items that are already discounted.
I even wrote HD and was ignored. So I stopped going to HD 5 years ago and now Lowes gets most of my business. My 7 brothers and Dad have now discovered Lowes as well.
Since then I found that IMO Lowes has better service, better hardware** and better tools (Irwin/Crafstman) the store is also cleaner and less crowded… the only thing I buy at HD is Ryobi power tools which I have standardized on.
i.e. At Lowes, I got a 10% veterans discount on $4000 of trex decking the year before last.
** strangely I recently discovered that ACE has the best hardware of them all!
Ace and Lowes gives lifetime replacement warranties on their craftsman and Irwin hand tools. They will even replace craftsman tools that were not purchased there.
Off the subject a bit but my grandkids like the ceiling projection devices at night.
They don’t take any wiring, space or generate heat at the ceiling.
I think we are over-rotating on the 'heat considerations. I would not expect twinkling LED’s held in a substrate to generate much heat. The only noticeable heat I expect is the power supply which should not be mounted in the ceiling anyway. Of course the devil is in the detail in that it depends on how many of what leds, what power level, what duty cycle.
Do these leds twinkle randomly, in a pattern or what? How are the leds driven?
19 Years this May at the HD and proud to still work there. If you heard what the HD did for all it’s employees during the pandemic and without hesitation or the need for social pressure to do so you’d be impressed. I don’t know what Lowes did for it’s employees but I doubt it came even close.
As for the lights they will be driven by an Arduino and for the original project two RC hobby batteries. The project was going to run for one event in a remote place with no outlets. But now this will be a semi-permanent install (when she’s older she can take it down if she wants) so Why not wire it up to an outlet. The code that was written if I remember is designed so that at any one given instant there is only one output pin powered at a time. The Arduino forums still has my topic viewable after all these years. I have to go back and reread it to relearn how the code worked and how I had planned to wire this all up.
I’ve still got all of the LEDs shrink tubed to long wire leads just sitting in a box in storage. I figured it was time to actually do something with them besides chuck them.
I agree, I was concerned about heat because I was thinking of this as a light fixture and had high-power white LEDs in mind.
This I don’t follow. Why would you not put the power supply in this cloud? If an arduino is powering the LEDs, the power draw will be insubstantial; a 1A 5V supply will be overkill. Practically any 5V “wall wart” supply will have enough current to run a simple sketch on an arduino where the current is limited to what an arduino GPIO can safely supply.
@raidengl just make sure that you do use current-limiting resistors appropriate to the LEDs. I’m guessing you already have those from the previous intended project?
Your not going to drive many leds driven directly from an arduino GPIO. There will likely be a driver somewhere.
I just would not put anything up there that could come down and hurt a 2 year old.
The original project was designed to run off of just the Arduino and the batteries. And yes I have the correct resistors already plugged in to a breadboard circuit sitting in storage. I didn’t need to do anything more permanent then a breadboard since it was a one event run time. I could still use the breadboard but it might be nice to use a more permanent solution. Since I want to plug it in to the wall I guess I could order a 5v wall wart and ditch the voltage regulator I bought for the batteries.
As for the thing falling on my kid I have access to the attic space directly above the room so I can run all thread up in to the attic if need be or install 2x4 blocking to screw in to. keeping it from falling shouldn’t be a problem. Plus if I make it out of foam board it should be rather light.
I wondered about the interior design trend of “ceiling clouds” so had a look on google. Some are literally pictures of clouds, or cloud shaped objects. However, most are panels suspended from ceiling, often for acoustic purposes, but also often incorporating light fixtures.
On the safety issue, heat is probably not an issue for low power LEDs. However, I have heard a lot of issues with wall-wart PSUs, including personal experience over the years such as having to evacuate my hotel at 3am. A recent visit by a Fire Safety Office to my company emphasized the problem, he said it was one of the top causes of fires they are seeing. He strongly recommended NOT charging your phone at the bedside - which of course most people do. However I did stop doing that.
So I would avoid putting any power adapter in the ceiling, or bedroom unless it is specifically designed for the purpose. Either way, avoid cheap wall-warts. If you do need low voltage DC, use a professional quality adapter designed for LED lighting (ie not from Amazon or ebay).
You probably already do this, but install smoke alarms in every bedroom and check them regularly.
