# making a reflector out of bare aluminum



## PEU (Sep 1, 2004)

I want to make my first custom light, and want it to be as short as possible.

Anyone tried to do an elliptical reflector ot of a piece of aluminum? 

I have in mind something like the head of the ARC AAA, but with an eliptical shape.

I know reflection will not be the same, but I have to do some compromises to try to do some really small.

May be winning 10-15mm in lenght is not as good as winnning in throw, but I want to try.

any comments suggestions are welcome! /ubbthreads/images/graemlins/thanks.gif

Pablo


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## PEU (Sep 2, 2004)

no one?


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## gadget_lover (Sep 2, 2004)

Probably not. It's not easy to do a perfect elliptical shape with common tools. Doing it with any sort of parabolic curve would make it VERY difficult.

If it can be just sort of eliptical you should be able to do it with hand tools like a dremel. and a lot of time.

I've turned small (1/2 inch across) simple single angle refectors on my lathe. After polishing they come out quite nice. You have to coat them pretty soon after polishing to keep them from oxidizing.

Are you planing to do two LEds? If so, you can do overlapping reflectors by offsetting the piece in a 4 jaw chuck with independent jaws.


Daniel


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## HarryN (Sep 5, 2004)

Hi - I am playing with reflector / optic / alternatives. Now these are not going to be competing in the CPF Olympics, but here is what I am playing with.

I found that a 5/16 th inch brass tube ferule is almost exactly a hand press fit on a Luxeon emitter. I took a dremel tool and notched away a recess on each side so that it misses the LED electrodes.

The idea is simple, yet inefficient, but sort of like a fiber optic - total internal reflection - of course in this case, certainly some losses. The main point is that it reduces some of the edge loss, and some of that is captured and goes out the front.

The ferule is a little short, so I am playing with brass tubing of similar size to extend it more. Once this is an acceptable beam, I will try to find a more reflective material, such as electro polished stainless tube.

I do not have any beam shots, and it is going to be at least 1 month till I can play with it again.


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## PAtwood (Sep 5, 2004)

What about coating the reflector with metallic spray paint as CPFers have suggested in the past? That way you can get the orange peel effect that helps smooth the beam out. Also, I wonder if it would make a difference if you used silver or 24k gold spray paint?


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## gadget_lover (Sep 6, 2004)

You can make flood type reflectors with relative ease on a lathe. Just turn a cone with the hole for the LED at the center. I did it this way;

Drilled a small pilot hole, then a hole the size of the LED.

Turn compound to about 30 degrees so teh sides of the cone will be at that angle. 

Using a small boring bar mounted on the QCTP, I bored out a cone. I started at the edge of the hole and worked my way to the outside, taking off about 20 thou of an inch each time. So that's back off the cross-slide .020, then run the compound in till you get to the hole in the middle. Back the compound out and back the cross-slide out another .020. Repeat. 

I make little cuts because I don't want to screw up the piece and I'm using a small boring bar on a HF 7x10.

By the way, did I mention that I don't really know how to use a boring bar? I usually start with the end of the bar against the lip of the hole, and use the compound to slowly cut away at the hole, up to 1/8 inch wide at a whack. Sort of like facing. I've also been known to simply use the side of the boring bar against the inside of the hole.

You should be able to use this technique to make two cones side by side or even overlapped.

Daniel


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## PEU (Sep 6, 2004)

Daniel, PM sent


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## PEU (Sep 8, 2004)

*Re: making a reflector out of bare aluminum (pics)*

I made the first one:

making the center hole






centering and aligning the elliptic shaped tool using a luxeon reflector









finished uncutted part





parting the reflector, to test it, the idea is to make the complete head with the reflector included, but, this was a proof of concept /ubbthreads/images/graemlins/smile.gif






finished reflector close to its plastic cousin





next post will be a beamshot of the turned reflector.


Pablo


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## PEU (Sep 8, 2004)

*Re: making a reflector out of bare aluminum (pics)*

I made some visual comparisons against a nx05 optic and the results were extremely disappointing, there was no hot spot just a flood of light, I guess this is because the shape was not correct or maybe not reflective enough. 

I'll try other shapes


Pablo


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## 4sevens (Sep 8, 2004)

*Re: making a reflector out of bare aluminum (pics)*

Pablo! Wait! Don't toss it.

I worked on some turned reflectors I got the same result, however,
I started polishing it with some jeweler's polish and made it
like a mirror - now I have a very culminated beam similar to my
arc4+

give that a try!


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## PEU (Sep 8, 2004)

*Re: making a reflector out of bare aluminum (pics)*

oops, this reply came fast /ubbthreads/images/graemlins/smile.gif

So you basically are saying that is a surface problem? do you recomend a creamy polish or just a high grit sanding paper? I have a micromesh set, but not used it yet, may be this is the time /ubbthreads/images/graemlins/smile.gif 

Pablo


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## 4sevens (Sep 8, 2004)

*Re: making a reflector out of bare aluminum (pics)*

I recommend a polish - not sandpaper.
Use the polish with a high speed dremel and a polishing tip.

I just went to ace hardware and they have a whole bunch of polishes
with varying degrees of grit.... make sure you get the finest
AKA jeweler's polish.

The results are very very satisfying /ubbthreads/images/graemlins/smile.gif

Now if I can only keep it shiny......


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## tvodrd (Sep 8, 2004)

*Re: making a reflector out of bare aluminum (pics)*

PEU,

Start with sandpaper, preferably wet-or-dry (used wet with water) with progressively finer grits. (at least 600 grit) until you can't see any tool marks, followed by metal polish like Wenol or SemiChrome, and you can get a "mirror" finish! Getting the parabolic geometry is the *****.

Larry


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## mahoney (Sep 10, 2004)

*Re: making a reflector out of bare aluminum (pics)*

When I polished my McFloods, I made a "tool", a plaster cast of the reflector with a "handle" created by extending a tube of paper and tape above the open face of the reflector. I used sandpaper up to 1500 grit and finished with Flitz metal polish on a piece of paper. 
Given the elliptical shape of your reflector, you would have to do something more complicated than just wrapping a cone of sandpaper around the tool. Thin strips of sandpaper should conform to the shape, or you could use lapping compounds (although that would mean making a separate casting for each compound to avoid cross contamination) The only other problem I could forsee is if the plaster is more abrasive than the finest compound.
HTH


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## mahoney (Sep 10, 2004)

*Re: making a reflector out of bare aluminum (pics)*

A couple other suggestions, that being free, are probably worth what they cost.
Theoretically, half of an ellipse should give the tightest focus available from that shape. Practically speaking, a luxeon is not a point source and a lot of the light output is baised towards the top of the high dome. Much of the output will never reflect off the reflector, unless you make it very deep. The only way to focus all the light output is with "re-coil" type methods ala Pelican, or a big optic like Inova.
The die of the luxeon should sit at the mathematical focus of the ellipse. Since much of the die will be around, rather than on, the major axis of the ellipse given the small scale of the reflector, a true ellipse may not be the most efficient shape. Perhaps an ellipse but stretched perpendicularly along the major axis around a cylinder maybe 1/2 the diameter of the luxeon die? This shouldn't be hard to do given how you are cutting the elliptical shape. 
Let us know how your experiment turns out.


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## Ctechlite (Feb 24, 2007)

*Re: making a reflector out of bare aluminum (pics)*



PEU said:


> next post will be a beamshot of the turned reflector.
> 
> 
> Pablo




Bump, did you ever get it polished and beam shotted?


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## gadget_lover (Feb 24, 2007)

Funny, I've been thinking of doing exactly the same thing for a light I'm designing. Grind the tool to 1/2 of a parabola and then cut the reflector from the body ofteh light. The reflector will be integral to the light to minimize the size. I'm going for a thin (flat) cell phone battery powered light.

How did that turn out, Pablo?


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## Ctechlite (Feb 24, 2007)

I think this is how Andrewwynn(sp?) modified his nano/Peak heads. I remember reading somewhere he profiled one of his dremel stones to the shape of a parabola and would just use that to shape the inside of the Peak heads he was using...Would probably take some digging to find the pics he posted, if they are even still up. They are probably about 2 years old now, lol. They are brass so most likely aluminum will polish up way nicer. Fivemega's 3.5" heads are just polished aluminum IIRC.


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## bombelman (Feb 26, 2007)

Whoa, long bump !!


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## Ctechlite (Feb 26, 2007)

Yeah, I was searching for something else, and this was one of the results, so I read it. I read whatever I can in the M/M/M forum. I saw there was no results posted so I thought I'd see if PEU had actually finished it.


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## PEU (Feb 26, 2007)

I abandoned that project long ago, if I manage to find the reflector I did, will try to polish it a little and give you guys some beamshots 


Pablo


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## 65535 (Feb 26, 2007)

I would slap it in the lathe, then use a bit of sandpaper up to 2000 grit and some good jewlers polish.


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## gadget_lover (Feb 26, 2007)

After turning you already have a fairly smooth, blemish free surface. It might (depending on how you made your finishing passes) have some ridges, but should not have a lot.

No sand paper is needed, just polishing. I wonder which alloy reflects the best?

Daniel


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## havand (Feb 28, 2007)

On my CMG Infinity Ultra I actually put an end mill piece into a drill press and cut a ball shape into the angled reflector. I then sanded and polished it. Not perfect..Wrong geometry, but I WAS suprised with how good of a finish you can get with bare polish aluminum


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## kevinm (Mar 1, 2007)

A machinist friend gave me a tip about cutting parabolas a while ago. The cheap glass cutting spade bits are roughly parabolic. I used a big one from Harbor Freight on a Peak Matterhorn and got a good looking beam. It compares favorably to the beam given by the Arc clones that were all the rage a while ago (both fitted with SMJLED's). I'd imagine it would be similar with a Luxeon.

Kevin


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