A Perfect Dedome?

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Tom E
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For me in the gas, the dome is always off or lifted, so not a problem with the dome. What I do is remove as much silicone material around the emitter as possible with tweezers without touching or getting close to the wires, but the emitter phosphor surface itself always comes out clean. I'll squirt iso. alcohol all over it before the work and after when all done.

MRsDNF
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Thanks for all the tips guys. I’m now an official member off the dedoming club after successfully using the petrol (gasolene) method on a poor little XP-G2. Theres a big brother XM-L in the tub as we speak.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

djozz
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MRsDNF wrote:
Thanks for all the tips guys. I'm now an official member off the dedoming club after successfully using the petrol (gasolene) method on a poor little XP-G2. Theres a big brother XM-L in the tub as we speak.

Congratulations MRsDNF! It is good fun to  find out what dedomed leds can do ! Laughing

Apart from being a flashlight snob I used to collect microscopes, so I use one of these to see what I am doing when dedoming:

(the famous Olympus SZIII zoom stereo microscope, introduced in the sixties, still widely used)

MRsDNF
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Thanks djozz. I put the XM-L in a P60 today and what a dismal failure. There was shadows everywhere. having a look under the magnifying glass there was a couple of remnants of the dome left which were dispatched with. Back in the light there was not a lot off difference. I machined the edge of the pill down to try and tune the reflector better but l could not get a nice beam at all with it. Drilling the hole out for the led also made little difference. Another type off reflector was tried to no avail. I cant see any remnants of the dome left but there must be. I will have to try it in a bigger reflector when the motivation returns.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

comfychair
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If you didn't already, try it with the thinnest possible insulator, or none at all if you can do so without shorting anything. They really have to be poked way up in there to throw a halfway decently tight spot.

djozz
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A dedomed led is focussed best when it sits just a bit deeper behind the reflector than when the dome is still on, because a dome (=positive lens) makes a virtual image of the die that is sitting 'deeper'. I don't know how to explain it better, sorry.

Perhaps that is what is happening here?

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Another trick to get it focused, since on a conventional MCPCB you can't raise the LED any higher than just where it goes, is to machine off some of the flat base of the reflector, the part that normally contacts the centering ring. That has almost the same effect as raising the LED (but not quite, as there's still no reflector surface 'behind' the LED). Also has the effect of enlarging the hole, due to the internal shape of the reflector surface. If you just bore that hole larger it's 'bout guaranteed to make the beam worse. (been there done that, way too many times)

djozz
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comfychair wrote:

Another trick to get it focused, since on a conventional MCPCB you can't raise the LED any higher than just where it goes, is to machine off some of the flat base of the reflector, the part that normally contacts the centering ring. That has almost the same effect as raising the LED (but not quite, as there's still no reflector surface 'behind' the LED). Also has the effect of enlarging the hole, due to the internal shape of the reflector surface. If you just bore that hole larger it's 'bout guaranteed to make the beam worse. (been there done that, way too many times)

Thing is that compared to a domed led, a dedomed led should sit not deeper inside the reflector but rather more backwards, so you need not machining the reflector down but use an extra spacer.

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djozz wrote:

comfychair wrote:

Another trick to get it focused, since on a conventional MCPCB you can't raise the LED any higher than just where it goes, is to machine off some of the flat base of the reflector, the part that normally contacts the centering ring. That has almost the same effect as raising the LED (but not quite, as there's still no reflector surface 'behind' the LED). Also has the effect of enlarging the hole, due to the internal shape of the reflector surface. If you just bore that hole larger it's 'bout guaranteed to make the beam worse. (been there done that, way too many times)

Thing is that compared to a domed led, a dedomed led should sit not deeper inside the reflector but rather more backwards, so you need not machining the reflector down but use an extra spacer.

I have found the exact opposite. But there are many different variations in p60 reflectors - some have a rather wide flat area/'shelf' around the emitter hole, some a narrow shelf, some a smooth taper all the way to the bottom. Who knows how many are properly designed and how many are just poor copies of copies of another design...

MRsDNF
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Thanks for the advice guys but believe it or not I tried all the above, hence the lack off motivation right at this point in time. The lathe does come in handy for machining pills and the back off reflectors. Its got shadows in the hot spot which makes me think that it must still have part off the dome on the emitter that I cant see. I’ve added some nightshots of the XP-G2 here at the end off the first post which I’m really happy with.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

Tom E
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Oh boy, the smallest light I used a de-domed emitter in was a C8, but got about 100 kcd with it, so doubled the kcd - it's a XM-L2 U2/SinkPAD running at 3.85A I believe. I haven't noticed any issues like that in the beams of all the de-domed lights I did, quite a few now. My biggest is my TN31 which is doing 347 kcd - pretty sick for under $10 in parts, posting in this thread: http://budgetlightforum.com/node/20454.

 I'm thinking the XM-L2's de-dome easier/better - pretty much all my de-domes, accept the very first, are XM-L2's.

 

djozz
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And all of my dedomes thusfar (exept for 1 test) are xpg2's and xpe2's Laughing I did them all hot, without the gasoline by the way.

tolight
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i just messed up the dome on an xm-l2 that i have…

has anyone tried octane booster?

i don’t have a gasoline container… and don’t really want to buy one just to get some gas so I can dedome…

thanks!

Tom E
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Maybe at the gas station, you can sneak a little into a glass jar - I had a small gas can so wasn't an issue. Since using gas, haven't had one problem -- did maybe 10 or so by now.

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tolight wrote:
i just messed up the dome on an xm-l2 that i have…

has anyone tried octane booster?

i don’t have a gasoline container… and don’t really want to buy one just to get some gas so I can dedome…

thanks!

how comfortable are you with light automotive work. ? If your fuel line is easy to access, you can disconnect it under the hood, put the line in a soda bottle, and turn the key to ‘run’ (NOT STSRT, DO NOT TURN IT ALL THE WAY AND CRANK THE ENGINE!!!) give it a good ten-count, then turn back to ‘off’, and go get the bottle, it will have enough gas in it to dedome, put the lid on for now, reconnect your fuel line, and close the hood, then find a jjar to put the gas and your led into.

Dunno if octane booster will work, but this is a relatively simple way to get gasoline without having to spend money on a ‘approved’ container.

comfychair
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Additives like octane booster are a different set of chemicals altogether as compared to gasoline. It's meant to be diluted in a full tank, and at those concentrations it's not harmful to the non-metal parts of the fuel system. But straight, undiluted? What are the odds that two completely different mixtures will give the same results? Have you bought a lottery ticket lately? Silly

tolight
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Dr Roger Trusty DVM wrote:

how comfortable are you with light automotive work. ? If your fuel line is easy to access, you can disconnect it under the hood, put the line in a soda bottle, and turn the key to ‘run’ (NOT STSRT, DO NOT TURN IT ALL THE WAY AND CRANK THE ENGINE!!!) give it a good ten-count, then turn back to ‘off’, and go get the bottle, it will have enough gas in it to dedome, put the lid on for now, reconnect your fuel line, and close the hood, then find a jjar to put the gas and your led into.

Dunno if octane booster will work, but this is a relatively simple way to get gasoline without having to spend money on a ‘approved’ container.

haha… great idea… don’t know why i didn’t think of that… access to the fuel line at the fuel rail is easy enough… Wink

that said, i may have found another option… will know in a few hours… i have some natural orange solvent, similar to turpentine/mineral spirits/acetone that seems to be working!

will report back… this would be a much ‘safer’ alternative to something like gas or paint thinner… some of those chemicals (like toulene) have very high toxicity ratings (4 on a scale of 5,? last i checked yearssss ago) and are proven carcinogens that are harmful if inhaled and can absorb through the skin…. (i start to get paranoid about stuff like this if i think about it too long… i used to work in high end art supplies and so was referring to MSDS more often than not for certain things… ick!

dedome, yes! de-health… no…. please be careful fellow BLFers!

happy and safe dedoming! Smile

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I use lighter fuel for de-doming (That stuff for zippos, I think it’s called ‘white gas’ in english). Its properties are similar enough to its heavier brothers used for cars, but is very clean.
Works fine so far.

tolight
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so my dedome worked!! I used D-Limonene, a product by a company called Tri-Art. Its used as a solvent for oil painting and is made entirely from orange peels… by this morning the silicone was dissolved, no residue except a little around the emitter, not unlike some other BLFers’ results with gas…

just hooked it up to my replacement Qlite driver Rev A… love the moonlite mode!

still only getting 2.4A or so at the tail… either my MM or … I’m not sure what but I think this is definitely my brightest light yet!! (ordered a couple of the ‘underatted’ V10 drivers from FT… if my MM is indeed accurate than the underperforming drivers will still give me higher amps for my C8 and T2R P60… I want to hit 3+ amps!!)

The beam is a bit ringy… i tried a couple of reflectors that I had… the OP reflector made the beam very floody. The way it is not the hotspot is more like an XP-G2 in a P60…

Anyway, the D-Limonene does work… and should be chemically ‘safer’ though it is still labelled poisonous…

Happy dedoming everyone!

Smile

… oh great… my light just shut off and won’t turn back on… fingers crossed its just the protection circuit on my protected 18650 kicking in… or did i just fry it… Sad

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While reflowing emitters onto sinkpads, Ive dedomed a few XML2’s and XPG2’s by accident. The domes come off completely and easily when they are at solder melting temperatures and leave no goo behind on the emitter.

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There's no goo left behind after gasoline dunking either, anything remaining is dry and crumbly and comes off easily (usually just by spritzing with denatured alcohol, which needs to be done to get rid of the gasoline anyway).

djozz
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FlashPilot wrote:
While reflowing emitters onto sinkpads, Ive dedomed a few XML2's and XPG2's by accident. The domes come off completely and easily when they are at solder melting temperatures and leave no goo behind on the emitter.

That is how I did my last few dedomes: reflow them on Sinkpad boards on a heatblock, quickly move the board to the stage of a binocular microscope and when the solder is just set, lift the dome off with the edge of a knife (exacto or in my case a scalpel).

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Finding solvents to remove the dome should easy.

Go here: http://www.coleparmer.com/Chemical-Resistance

Choose “Silicone” in the Material box, “All” in the Chemical box, and “D – Severe Effect” in the Rating box.

Anything that comes up on the results page will have a pretty significant effect on the dome. It’s just a matter of trying some of them and seeing what is fastest / cleanest / cheapest / whatever.

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I think the fastest/cleanest/cheapest/whatever has already been found, and it might just be mentioned somewhere in this very thread, though I will admit it is hidden pretty well and it will take some expert detective work to find it....

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comfychair wrote:

I think the fastest/cleanest/cheapest/whatever has already been found, and it might just be mentioned somewhere in this very thread, though I will admit it is hidden pretty well and it will take some expert detective work to find it….

Sure, gasoline works well, but there’s quite a few other solvents which may work better. Just trying to help.

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May work better? How, exactly? Quicker? Is ~3-4 hours not quick enough? Is 'all' the silicone gone not enough silicone removed - is there another chemical that might remove not just 100%, but maybe 110%? (and would that really be 'better'?) Cheaper? Doubt it. Easier to get then gasoline? Can I drive 2 blocks from my house anytime day or night and get 5 gallons of anything on that coleparmer.com page for less than $20?

I don't get it. Why are so many trying to come up with something that 'works better' than something that just works? It works. If you don't think it will, try it first before you go looking for alternatives. That's the whole reason this thread was started. Because somebody found the answer.

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comfychair wrote:

May work better? How, exactly? Quicker? Is ~3-4 hours not quick enough? Is 'all' the silicone gone not enough silicone removed - is there another chemical that might remove not just 100%, but maybe 110%? (and would that really be 'better'?) Cheaper? Doubt it. Easier to get then gasoline? Can I drive 2 blocks from my house anytime day or night and get 5 gallons of anything on that coleparmer.com page for less than $20?

I don't get it. Why are so many trying to come up with something that 'works better' than something that just works? It works. If you don't think it will, try it first before you go looking for alternatives. That's the whole reason this thread was started. Because somebody found the answer.

Basically +1, but I know others have proven, familiar methods that are 100%, but I've found the gas method certainly the best for the average smuck (me...). I don't even wait 3-4 hours now - I'll take it out in 2 hrs if I need to, and gently flip off the dome because it always seems to be very loose then, and leaves a pretty clean footprint, as comfy says. I just give it a good soaking/shower of isopropryl alcohol when it's out, and maybe knock off loose stuff around the emitter. I'm still 100%, even after doing 1 more last night, and got another soaking now, probably 15 or so total.

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Looking for a way to dedome my C8 XM-L T6 without soldering, I pulled the wires out and separated the LED/star from the pill, turned it upside down in a tiny container of gasoline with the pill sitting on top. (Tiny gas container consists of a little clear plastic cap from a bottle of throat spray!)

We’ll see how it goes from here! (do you think the gas vapors will harm any of the contents of the pill?)

Thank you!

Edit: Seems like some kind of spray contact cleaner would be good to finish up with…what do you think?

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tallboybass wrote:
Looking for a way to dedome my C8 XM-L T6 without soldering, I pulled the wires out and separated the LED/star from the pill, turned it upside down in a tiny container of gasoline with the pill sitting on top. (Tiny gas container consists of a little clear plastic cap from a bottle of throat spray!) We’ll see how it goes from here! (do you think the gas vapors will harm any of the contents of the pill?) Thank you! Edit: Seems like some kind of spray contact cleaner would be good to finish up with...what do you think?

Even if you dunked the whole pill, driver and all, it wouldn't hurt anything other than the trouble it'd be to clean it well afterwards. Or if it used silicone wires... PVC or teflon should be unaffected. Epoxies or sealants could also be affected, though JBWeld I know will tolerate quite a bit of gasoline exposure before it starts to go soft. Others may be more vulnerable.

I've only ever used isopropyl in a spray bottle to clean up afterwards, I know first-hand it won't damage the newly exposed phosphor layer on the LED (that's the only part that might not be compatible). Use more aggressive stuff with caution. Might be best to test it on a 'dead' de-domed LED first.

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comfychair wrote:

tallboybass wrote:
Looking for a way to dedome my C8 XM-L T6 without soldering, I pulled the wires out and separated the LED/star from the pill, turned it upside down in a tiny container of gasoline with the pill sitting on top. (Tiny gas container consists of a little clear plastic cap from a bottle of throat spray!) We’ll see how it goes from here! (do you think the gas vapors will harm any of the contents of the pill?) Thank you! Edit: Seems like some kind of spray contact cleaner would be good to finish up with…what do you think?

Even if you dunked the whole pill, driver and all, it wouldn’t hurt anything other than the trouble it’d be to clean it well afterwards. Or if it used silicone wires… PVC or teflon should be unaffected. Epoxies or sealants could also be affected, though JBWeld I know will tolerate quite a bit of gasoline exposure before it starts to go soft. Others may be more vulnerable.

I’ve only ever used isopropyl in a spray bottle to clean up afterwards, I know first-hand it won’t damage the newly exposed phosphor layer on the LED (that’s the only part that might not be compatible). Use more aggressive stuff with caution. Might be best to test it on a ‘dead’ de-domed LED first.


I’m excited about maybe coming up with a way to dedome without soldering! Good point about the layer of phosphor, thanks. I’ll try finishing with alcohol like you said, I’m guessing the force of a stream shot from a bottle helps with clean-up of remaining silicone vs. just soaking in it?

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