A Perfect Dedome?

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...

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.

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: https://budgetlightforum.com/t/-/17637.

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.

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

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!

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.

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.

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? :p

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! :slight_smile:

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.

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!

:slight_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… :frowning:

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.

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).

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).

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.

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.

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.