grinding LED's

grinding LED\'s

Has anyone dared to reshape a led to improve or change the light output? I was very impressed with the (Turtlelite I), Dorcy led bulb which works almost like a regular bulb in a spot focusing type flashlight. The "patented" led just looks like it was ground down and not even polished. It seems deceptively simple but I think that it has optic-calculus geek thought in it. This led bulb just might replace the spare in my 3d mag clone.

Re: grinding LED\'s

It's a lot tougher than it looks but the worst you can end up with is a terrible beam patern. Many have attempted it, sucess varries...

I have only done it with a blinking 5mm Red LED (From packaging from a certain computer device ) I did this because, when using the LED as a marker device (A'la tent when camping) it makes it much easier to spot...

Re: grinding LED\'s

There's no mystery in grinding down an LED. You only need:

- a file (even a nail file or emery board will do)
- fine sandpaper (1000 grit)
- any good metal polish (eg. Brasso, but I use Autosol)

I normally grind off excess epoxy til its almost down to the die cup and rinse clean with water. Then I shape it as evenly as possible with the sandpaper (rinse again). Finally, polish to near factory shine using the metal polish and some paper towels first, then polishing cloth.

This method has worked like a charm for me many times and is fairly easy to do. The result is a widespread beam, which mau look dim, but is excellently caught using many 'normal' flashlight reflectors.

If prefer to practise a little first before committing to an expensive nichia part, try it out on some cheap LEDs first until you've gotten the idea and hang of it.

Good luck!

Re: grinding LED\'s

Just don't file it so close down that even the wires leading into the die cup are filed away...

Re: grinding LED\'s

Whew! I'm impressed with a factory shine which this Dorcy led-bulb doesn't have. Should I shine it up to let more light straight out or does it reflect it sideways/down into the reflector? What would mirroring the "dome" do to the light spread?

Re: grinding LED\'s

It seems that most people are grindng thier LED's to make them work in standard reflector torches. What about placing the LED in backwards so that its beam is focussed at the reflector's focal point? I'm thinking of modifying a paraboliic reflecting car spot light in this manner. This works exactly like a satellite dish in reverse! I've just got to find a torch with a large enough bezel to take the spotlight!

Re: grinding LED\'s

I had the same idea but projecting the light out to the sides. I was wondering how effective, say a star shaped module with 5 to the sides (in a star) and one front. The light going out to the sides would hit the reflector and throw a long beam, and the forward mounted LED would make a close range work light. Also if such a module were used in those cheap convertible flashlight/lanterns it would be awesome as a 2 way light.

I would like to see how this would work if anyone has the time and resources to try it.

Re: grinding LED\'s

Ya, putting an extra regular led or more would make it a better work light but there isn't much space around the "filament" zone. It's a drag but I'd have to swap the "bulbs" for a different type of light.

Re: grinding LED\'s

I think any of the above ideas would work fairly well, provided you do the math for the optimum optical effect. At the end of the day, IMHO, its more simply a matter of "was it worth the effort?".

Another challenge is that you'd have to redesign everything if the module were used in a flashlight that had even a slightly different size/shape reflector. The variables involved are indeed daunting.

In any case, the amount of light coming out from a single 5mm LED is finite and the best reflector in the world wouldn't be able to change that.

The Dorcy and PT Impact have very impressive output most likely due to severe LED overdriving. Both have excellent spot qualities, but at the ultimate expense of beam spread. And, yes, even focusing LED flashlights have that Maglight "hole-in-the-middle".

EMPOWERTORCH has an interesting idea with the backward-firing LED, but if I recall, some searchlights similar to this design have a "mercedes benz star" shadow and black hole in the middle.

Re: grinding LED\'s

Does grinding only serve to widen the beam? I didn't realize that the tight spot on the Dorcy Cool Blue and Turtlelite I came from the reflector.

Is it possible to grind in a way that would tighten the beam a bit? For single LED keychain lights the white 5mm Nichias have a beam that is a bit too spread out for the amount of light one of those LEDs puts out.

Could a Photon or Arc AAA be grinded to tighten the beam a bit, or could some extra epoxy be carefully molded (or glopped on and grinded down afterward) on the end to achieve that effect? As I understand it, the different beam angles from most LEDs come from the packaging, not from any difference in the emitter itself.

- Russ

Re: grinding LED\'s

r2,

Theoretically, all of what suggest is possible - but is really hard to do at home. Grinding an LED flat is simple, but getting it "just right" when epoxying on, or refinishing an LED to a new profile is gonna be a painstaking nightmare.

Grinding removes the focusing effect of the LED's built-in epoxy lens. When ground down, the LED will be giving you almost 180 degee dispersion. This makes it easy for the reflector to catch and redirect light forward. Contrast, if you will, the average 5mm LED has beam angles of about 15 to 30 degrees. At such angles, most light is already going forward in a narrow cone, too narrow for a reflector to be of much use, unless its very deep - ever notice how deep the Dorcy's and PT Impact's reflectors are? The Impact goes further by using an additional lens to shape the light.

Re: grinding LED\'s

I had the same idea that Ratso had. I was thinking about mounting 4 LS emitters on an Al post, so they were all pointing perpendicular to the beam direction. Then nearly 100% of the light would be shining into the reflector.

I've also thought about putting a small reflecting mirror on the backside of the bezel lens (acting like a compound telescope - redirecting the forward light into the reflector).

So many ideas, so little time
-Darin

Re: grinding LED\'s

Hmmm, sounds like the luxeon side-emitters are what you guys need...

Re: grinding LED\'s

what would a concave tip on the front of a led to? or a sharp point?

i would think that a concave would produce a fairly tight beam, and that a point would result a "hole-in-the-middle" type beam pattern...any thoughts? how about other vaious shapes? a phillips screwdriver head perhaps =) ?

Re: grinding LED\'s

Thinking to the backward facing LED and the Mercedes-Benz shaped hole...this hole could be filed by having a forward facing LED back-to-back with the backward facing one. I've not tried any of these ideas yet but I have found a torch that should work well with this principle as it has a very deep faceted reflector ...the Benross 4033... It's sturdy and reasonbly cheap... this torch was used as my first test-bed for bulb-mounted Nichia's and worked very well in the demanding mountain environment of Nant Gwynnant in North Wales.
I have plans for a few multi-LED permanently-modified 4033's...watch this spaace!

Re: grinding LED\'s

Hey dudes, should I polish the Dorcy led-bulb tip or not? Were they too cheap at the factory to do it or is not worth it or will it make it worse?

Re: grinding LED\'s

While not an expert on this topic, if the led is easy to access, and there is no chance on crapping up the reflector, i would say that it could only improve things.

Re: grinding LED\'s

I've done a few of these and I would suggest grinding by putting the LED in a drill and
applying the file to the rotating LED. It makes
the surfaces symmetric. The cone makes the light disperse to the sides better. If you leave it flat, it all comes out the front.

Re: grinding LED\'s

JoeyL said:

I've done a few of these and I would suggest grinding by putting the LED in a drill and
applying the file to the rotating LED. It makes
the surfaces symmetric. The cone makes the light disperse to the sides better. If you leave it flat, it all comes out the front.

Click to expand...

Will it be harder to polish after grinding a convex cone like that?

[I realise that this thread is 14 years old but the laws of physics haven't changed in that time and light continues to behave in the same way. This thread is the top Google result for my search and will always be relevant to someone wanting to make a side emitting LED that isn't available commercially (in my case a flickering LED for flame simulation)].

Re: grinding LED\'s

Not a problem to bump an older thread IMO. I'm certainly no expert on your query, but my only thought is that component materials may have changed in the interim - going from a hard dome (I know that the Cree MC-E was that way - modders used to chemically etch the glass dome) to a modern silicone dome which is far softer and would probably require a different technique.