X-ML de-doming method with 100% success?

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HAL
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X-ML de-doming method with 100% success?

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Only attempt to de-dome an LED if you are willing to do an emitter swap or scrap the light! Expect failure on your first de-dome procedure and treat it as a practice run. To maximize chances of success stick to the methods and the appropriate tools suggested

I tried to make a very brief summary of the main methods of de-doming that have been contributed to this thread. Sorry for not linking to the contributors as yet, this is a preliminary summary that I will flesh out later this week when I have time.

The three main methods of de-doming are as follows:

Heating the LED:
The LED PCB can be heated by an iron, stove, or the LED driven at a high current, to the point where the dome softens and can be pried off. Sealing the bare LED afterwards is recommended. Risks involve damaging the LED with heat, dislodging the LED from the PCB when the solder melts, damaging the LED bond wires as well as removing phosphor from the emitter surface. This is the “original” method of de-doming and the most popular.

Heating the LED dome:
An iron or other hot implement is used to heat the dome uniformly until it is soft enough to be pushed off, in the direction of the LED bondwires. Sealing the bare LED afterwards is recommended. Risks involve damaging the LED bond wires as well as removing phosphor from the emitter surface. This method has not received much testing as yet.

Slicing off the LED dome:
A very thin, very sharp blade, such as a razor, is used to slice off the LED dome a millimeter or less above the phosphor layer. A spacer/shim for example a washer of appropriate thickness can be placed around the LED to act as a guide for the blade. The motion of cutting should be a single push or slice to allow for a smooth clean cut. A dremel or fine grit sandpaper can be used to polish of the surface afterwards IF needed. Risks involve nicking the LED with the blade, getting too close to the LED and destroying it during polishing. This method provides seemingly less reliable results than removal of the entire dome provides.

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I’ve stumbled across an easier way to de-dome an XM-L that should yield close to 100% success if one is careful (maybe its been discussed before but I didn’t see it). I just dont know how much light is lost in the process since I didn’t have the good sense to take before and after beamshots.

Anyway The method is to take a razor, like this (the sharpest, thinnest thing I could think of) and just slice the dome off as close to the surface and possible, leaving maybe 1mm or less of material. Mine actually came out quite untidy but the beam still had no artifacts, though this probably affects brightness a bit.

I did it to a UF 3mode dropin. The beam is about 50% smaller and more intense, with a slightly warmer hotspot. Another pro of this method is that the thin layer remaining above the phosphor means that there will be no degradation of the LED over time through oxidation etc. My previous attempt at de-doming ended up ripping off some of the phosphor, which resulted in a purple bulls-eye in the hotspot.

It would be nice if someone with a luxmeter could replicate this and check the results.

Edited by: HAL on 09/30/2012 - 11:00
_the_
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Sounds very interesting. I might try this later this week with one of my lights. If I break the emitter it gives me a good reason for buying a new, brighter one.. Wink

=the=

 

Ledsmoke
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This sounds interesting but honestly? I am just not sure I have the b@lls to do it.

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

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MattSPL
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Interesting. I’m tempted to try this. Do you have any pics?

_the_
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Just tested it with my FF STL-V6 and the results were (arbitrary units):

 OriginalDedomed
Ceiling bounce4740
Throw50006170

=> 23.4% more throw with a simple 2 minute operation.

(could have shaved it closer the emitter surface and cleaner and..)

=the=

 

HAL
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the wrote:

Just tested it with my FF STL-V6 and the results were (arbitrary units):

 OriginalDedomed
Ceiling bounce4740
Throw50006170

=> 23.4% more throw with a simple 2 minute operation.

(could have shaved it closer the emitter surface and cleaner and..)

That was quick!!! results look really promising…

Ledsmoke, MattSPL

I can post pics of the emitter tomorrow if you want,but there’s nothing special really. Cutting off the dome is a lot easier than it sounds, you don’t need to cut it off in a perfect single pass, you can cut it off a bit higher then “carve” off pieces till you get to the desired level.

edit to add: One thing that surprises me is that the ceiling bounce indicates only a 15% light loss from this method of de-doming… I was lead to believe that de-doming caused something closer to a 25% light loss, great news.

JohnnyMac
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Nice! I've been thinking of sanding down and polishing to dedome one but this way is FAR simpler. I can't believe I didn't think of it myself. Silly

I wonder what a difference it would make in an HD2010?
MattSPL
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HAL wrote:
the wrote:

Just tested it with my FF STL-V6 and the results were (arbitrary units):

 OriginalDedomed
Ceiling bounce4740
Throw50006170

=> 23.4% more throw with a simple 2 minute operation.

(could have shaved it closer the emitter surface and cleaner and..)

That was quick!!! results look really promising…

I can post pics of the emitter tomorrow if you want,but there’s nothing special really. Cutting off the dome is a lot easier than it sounds, you don’t need to cut it off in a perfect single pass, you can cut it off a bit higher then “carve” off pieces till you get to the desired level.

Ok thanks.
Is the dome solid, or is it hollow once you cut the top off it?

So will actual output decrease, but throw should increase?

HAL
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yep 15% drop in lumens, increase in throw. What remains of the dome is just a thin sliver acting as a flat lens.

JohnnyMac, well after cutting the dome down its left quite rough, so maybe polishing might help after that?

MattSPL
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HAL wrote:
yep 15% drop in lumens, increase in throw. What remains of the dome is just a thin sliver acting as a flat lens.

JohnnyMac, well after cutting the dome down its left quite rough, so maybe polishing might help after that?

Ok thanks Smile

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MattSPL wrote:
Ok thanks. Is the dome solid, or is it hollow once you cut the top off it? So will actual output decrease, but throw should increase?

It's solid. And yes output will decrease when dedoming an emitter.

=the=

 

MattSPL
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the wrote:

MattSPL wrote:
Ok thanks. Is the dome solid, or is it hollow once you cut the top off it? So will actual output decrease, but throw should increase?

It’s solid. And yes output will decrease when dedoming an emitter.

Ok, thanks. I might give this a try on my spare Trustfire Mini-01 and see if i can turn it into a pocket rocket thrower Big Smile

JohnnyMac
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I wouldn't be so quick to say output decreases. Identical drivers and emitters in different hosts, flood & throw will yield different ceiling bounce levels. Flooders score higher in bounce tests because they scatter more light than a thrower.

A stock domed xm-l spreads light 125 degrees. Cutting off the dome focuses the light reducing ceiling bounce numbers but increasing lux numbers for throw. The lens on an emitter doesn't increase the lumens produced, it just refocuses them. If I'm wrong I'm sure someone will be quick to correct me and explain why.
HAL
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Well from what I understand, the dome on an LED not only refocuses the light, but allows more light to escape from the emitter that would otherwise be reflected backwards. This is also the reason why the tint becomes slightly warmer after de-doming.

MattSPL
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Ok, just cut most of the dome off the xm-l in my trustfire mini-01.
Any suggestions for polishing it a bit?

Preliminary results are: hotspot is smaller and slightly brighter to the eye.

mags
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Anyone up to de-doming a TN31? :bigsmile:

gcbryan
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How about someone with spare XR-E’s and a lux meter measure the lux from a cheap thrower (Smallsun ZY-C10-S for example) and then cut the dome off and remeasure? Smile

I’ve gotten rid of most of my cheap experimental lights or I’d do it.

Boggy
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I was planning a 4A driver and an aspheric mod on my STL-V2. I might add the de-doming to the To Do List.

What are the side effects of this procedure, except the (said) lower lumen output and warmer spot? Will it suffer more from the 4A current than it would without de-doming?

Slewflash
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Looks like a lot of people have successfully dedomed their lights. I might have to dedome my stl v2 soon Big Smile

Slewflash 

Slewflash
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Boggy wrote:
I was planning a 4A driver and an aspheric mod on my STL-V2. I might add the de-doming to the To Do List.

What are the side effects of this procedure, except the (said) lower lumen output and warmer spot? Will it suffer more from the 4A current than it would without de-doming?

I think dedoming isnt good for an aspheric light, because when dedomed more light hits the reflector or in this case the inside of the head and not the lens which is what you want.

Slewflash 

Boggy
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I see, thanks! I’ll see how the aspheric mod goes, and if I’m not satisfied I’ll try dedoming it and remove the lens.

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Note: Don’t use a pocket knife no matter how sharp you think it is. It WILL stuff up your dedoming.

My STL-V2 now has a smaller spot than the 7G5-V2, but lumens has drastically gone down. I did a choppy job at dedoming, so I tried to file it down. It worked, but then I had myself a frosted dedomed LED which decreased output even more. Throw also dropped about 2k lux @ 1meter

Slewflash 

scaru
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Ouch. Sad Sorry to hear that. 

LowLumen
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I confess to slicing my XM-L T6 3C with an exacto knife a few weeks ago. It was not for more throw; it’s in a mule light and followed from frustration at the color separation problems in the XM-L. The yellow to green exits around the edges, (having traveled through more phosphor than the light coming straight out the top) while the more blue/violet comes straight out. I did not do such a nice neat job either, but I will say that it greatly improved the color separation and seems to have made the light more dispersed. Unfortunately, I did not do any before/after measures of light output (not a premeditated act!) but for my use, it was absolutely a success.

I think you have the right idea with a straight razor blade, but (if I were to do it again) I would lay a washer of proper thickness around the LED and make only one straight clean cut using the washer as guide for the blade height across the LED.

DrJones
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I did the same some months ago, with a paper cutting knife. Surface wasn’t too nice, I tried to polish it a bit, but it stayed somewhat diffuse. Result was about 30% more intensity with a small aspheric lens. I never built a light with it though, it just laid around for months… I actually had expected more. Maybe I’ll try some more polishing somewhen with 1000 grit.

Manual Man
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Just de-domed a U2 using this method: wider beam angle comparing it to a X9 minus reflector. In the 73mm DX reflector the beam is near parallel however not quite as much throw as I had hoped, a few rings as well (I used a Mora to cut the dome, probably not the best idea)… if it wasn’t for the light reflecting of dust in the air I think I might be able to make out the hillside 1Km away with it, trees at 500m are no problem.

MattSPL
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Here’s a pic of the XM-L and pill from my Trustfire Mini-01 after i cut the dome off.

Here’s a beamshot. Trustfire Mini-01 on the left. De-domed Mini-01 on the right.

TadpolePilot
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|( |( |(

Now we all just want to stab and cut the dome off!

Thanks for bringing me to see the Light! LOL Party

"Yell  {"Old, Broken Butt,  Zeide"}&nbs

MattSPL
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TadpolePilot wrote:
|( |( |(

Now we all just want to stab and cut the dome off!

Thanks for bringing me to see the Light! LOL Party

Big Smile
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How did you cut it off?

MattSPL
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I used a new Stanley knife blade. I chopped off about half of it first, then carefully shaved off layers until i got as close as i dared to the board. There’s probably around 0.5mm – 0.75mm of dome left.
I then carefully rubbed the remaining bit of the dome with a glasses lens cloth to try and polish it a bit.

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