Hello!
For my current project i could use a few LED reflectors, since i can not find one that is to my liking i would like to build one my own.
The idea is to build a stamping form tool with my 3D printer and stamp out a few out of thin Aluminium sheet material.
But i got a hard time to figure out the curvature of the reflector, after i asked google i feel like i am in 5th grade math class again.
Is there any way to make this a bit easier?
I would like to calculate the ideal form of the mirror instead of just roughly guesstimating something, my CAD program is Fusion360.
It would be a parabolic solid, or paraboloid. There may be some minor changes from that perfect shape, since the LED is not a perfect spot point of light. But, if you just make a paraboloid, you will surely be close enough.
That’s quite the challenge, to make yourself a reflector that is better than what you can buy…
It’s not just the shape, it’s also the reflective coating that makes a good reflector.
The coating is condensed pure aluminium vapor, which is quite impossible to do yourself…
Polishing aluminium will never give the same results.
In the old days (like before 1950s or something) they used silver too, which can be done by yourself, but it oxidizes in time and always gives a slightly yellow tint.
Stamping aluminium sheet into a parabolic reflector is not easy either…
Can i ask what you want from a reflector and where / how stock reflectors fail to meet your desires?
Thank you, that helped a bit but it seems Fusion has no function for that, ill look further into it
Thanks for the reply!
Polishing the aluminium to a somewhat satisfactory finish i can do, did that a few times already, i have decent polishing compounds.
It does not have to be perfect, it just has to be a bit better then the lens i am currently using that looses a lot of light to the sides.
I cobbled together a bit of a test out of some paper and aluminium tape and it already produces a much better beam pattern then the lens so i think it should work out fine.
Of course you can ask
I want to replace the lens on this thing with that reflector:
The whole thing can be completely redesigned to fit the reflector, it does not have to go into these parts of course.
I got around 20mm in diameter and 5 to 15mm in height, maybe reflector is a bit too fancy of a word.
There are two reasons not to use a pre-made reflector, i can not find one in a suitable size and price, locally since i do not want to order in china and wait two months.
The other is, that i want to make one myself, i like challenges.
There are quite different designs for reflector shapes even if its the same size and depth
I saw different results having 2 identical sizes just the one had pretty much a very tight hotspot then degrading brightness until puse spill
the other has a tight hotspot and a cone with a brighter spill with sharp edges and rest normal spill
to get the real brightness I would need to stack a HDR image
Dark red is the average (most popular) reflector proportions.
It’s a section of a parabola.
The lobes represent the amount of light based on the half sphere of radiance from an average power-LED.
Oops, i made a mistake…
That 0.06 should be 0.12 :person_facepalming:
I assume this is not a focussing issue, like the one having a thicker flat base than the other one…
I have seen a few reports of XR-E reflectors throwing farther than XM-L(2) reflectors.
Apparently they’re not all just a section of a parabola.
Could production precision be a factor too?
Aha, i see.
You want to replace that TIR lens / reflector.
Yeah, they do seem to lose a lot of light from the sides.
But is it worse than the losses of a alu coated reflector?
I don’t think so, but i’m not sure.
I guess you also want to get rid of the light shining through the red plastic?
It’s not easy to find the TIR you want (in my experience).
Sooo many different ones out there…
I have a cheapo UltraFire tube shape 18650 which has a cheap plastic smooth reflector.
I have a TIR that fits very well inside that reflector, i’m running an Oslon square 95CRI 2700K on 3x 7135 in it, and it’s a lovely light (i.m.o.) and the loss of light is probably reduced just a little bit too.
But i doubt it’s a significant gain in output.
But maybe you can find a cheap plastic reflector to do something similar with that TIR.
(just an idea)
I like TIRs.
They can eliminate the tint shift, unlike a reflector.
The light shining though the plastic does not bother me, i could solve that problem with a bit of aluminium tape, it actually is loosing quite a bit of light in there though.
Enough that i can see a noticeable difference, even a crappy aluminium reflectors produce a better light output, i cobbled something together:
Before i started, i spend a few days looking through different sources to see what type of pre made lenses and reflectors are out there, in the end only this one make the cut.
But i may be a bit picky too, i admit that.
Give me a week or two
That is my fallback idea, id like to just just a press tool but metal spinning a reflector should work too, i can improvise something with my drill press or wood lathe.
