First time SRK build tech help!

Those where the only ones I saw available right now.

Just a possibility for the SRK, would be nice to have a single copper MCPCB that fit the SRK. Wouldn’t mind spending 40 or so on it.

Many people have wanted this, the issue is getting it made. The buy in cost would be close to $1000 if I had to guess.

Then you have to figure out which SRK model you want to target, the 4x? 8X? more?

WOW! fare cry from what I was thinking lol. I see exactly what your saying though.

OK, just purchases the XM-L2 U4 A1’s from Mountain. Really not crazy about that temperature, a little to blue for my liking. But if I don’t like it I’ll order another set of emitters later lol

There was a company that posted a few months ago about custom mcpcb’s. I think Jos(Djozz) worked with them on a Nichia 119 copper star. If you do consider going ahead with that post an interest thread and I’m sure you’ll get takers, many of the early group buys were on parts as opposed to whole torches. Maybe RMM would be interested in stocking some along with his SRK drivers. 3/4 LED mcpcb’s will probably be the most popular as beyond that number the light turns into a flooder. It might even be possible to design one that fits either 3 or 4 LEDs.

To understand why LEDs overheat you have to understand the heat path. The led die that makes the light gets very hot and sits on a small square fiberglass substrate with thermal conduits from the die to the heat pad. This is soldered to the metal core pcb on +/- and heat pads which conduct the heat to the metal below. Most have a layer of copper, then an insulating layer, then the metal core. That insulating layer slows the transfer out of the die and into the core and when sharing the same core the back up can become critical and the LEDs poof. DTP (direct thermal path) has no insulating layer under the heat pad to slow the transfer and copper conducts heat much faster than aluminum so the back up won’t occur there, instead one must look to the next stage in the heat path which is from the mcpcb’s to the host, that is where your slug comes into play. It creates a buffer that also has more surface are in contact with the host. What you’re looking to do is create or maximize the ability for heat to move from the die(s) into the host and/or your hand. To do that you can try to maximize the surface area across each break in the thermal chain while minimizing the thermal resistance at these breaks.

If I do everything just right it should be one bright flooder. I’ll test each emitter after floating them to make sure all is good. Been wanting to do this for a while now and just ordered all the parts in the last couple of days. Texas Ace saved my skin big time by mentioning the foot print size. Now I have 6 extra XP-L2 V5 emitters to play with. I have gone over what needs to be done several times now. After the build I’ll use my thermal gun to see just how hot its getting when in full throttle. Between getting the wrong and right emitters that was about a 60 dollar pooch. Better then a smoking flashlight. A copper MCPCB for a 3 emitter would be nice.

I recently finished my first SRK build so I wish you luck. It was also a triple though I used some old T6 3D’s. Rather than Dremel the back of the reflector I cut some .5mm copper sheet to make thin buss bars to connect the 3 copper DTP stars and made a hollow copper puck for them to sit on. Dale did a version of the buss bars so I gave it a shot. The thing is stupid bright.

Thank you, cant wait to see the results. If all goes well I think a 3 emitter is next.

Those emitters will come in handy though I think you’ll find parts seem to accumulate more rapidly than finished projects.

Lol, Iv’e noticed that and I’m just starting out. Nothing like spare parts.

They come in real handy if you participate in the annual contest.

I use a full heat gun (the big ones that are like a super hair dryer) to reflow the srk mcpcb’s. Even my 100W reflow gun would take forever to reflow the LED’s and you don’t want them hot any longer then needed. Plus it is way easier and simpler to use the heat gun. The MCPCB is just so large and thick it takes a lot of heat to reflow the solder. Careful to not overheat it though.

Once the solder melts pull the heat gun away and keep it far enough back to just keep the solder liquid while you check the LED’s and tap them to make sure any excess solder is tapped out. See VOB’s video for an example.

Just a thought:
The less current a LED gets, the more efficient it will work and then you don’t need copper DTP boards.
So if you have 6x XM-L2 running on 2 Amperes each, you will have some (guesstimated) 5000 lumen of LED light with a total of 12 Amperes current and less heat problems and lower Vf (so it will stay 5000 lumens until the batteries are discharged)
The same power on only 3x XM-L2 (4 amperes for each LED) will get you some (guesstimated) 3800 lumen and then you need DTP boards and a triple reflector.
And the Vf will be higher, so the output will get less when the batteries become discharged.

I bought a ZENY 862D+ solder station a couple weeks ago and have been practicing re-flowing emitters. I’ve been keeping the temp around 275 Celsius and it seems to work really well and fast. I like the heat gun idea, all at once, would hate to over heating the mcpcb doing them one at a time, of course I would let each emitter cool to room temp if I do them one at a time. I’ll be using Kester EP256 Lead Solder Paste 63/37, hope it’s good solder. With the syringe I’m able to get just enough without over soldering. Quick question, how many times can an emitter be re-flown before it degrades?

You end up with more of a flooder which won’t seem as bright even though lumen output is greater. That’s ok if flood is what you want from your lumens. One mod that’s been relegated is the gorilla DTP where a hole is drilled through the heat pad and filled with copper wire. That would allow the use of the stock board at increased output though not as high as full copper DTP. So far I’ve just switched everything to copper DTP but the expense goes up with bigger multi-die lights

It is not possible to reflow a single LED on a mutiple LED MCPCB. They will all reflow at about the same time regardless of where you apply heat. Makes sense as the entire point of the mcpcb is to spread heat.

Small mcpcb’s are easy to reflow, I use my reflow gun set to around 400c for those, since you are heating from the bottom as long as you stop applying heat once the solder melts (by pulling the reflow gun further away) it will be just fine.

Even if you think you have the right amount of solder, I would still tap the led to squirt out excess. If there are any air gaps under the LED it will drastically reduce the thermal path and cause it to overheat. I tried to get the solder paste perfect at first but I think I got about 25% right to the point I was happy with it without tapping.

I have the SRK 32x 7135 Driver - V2 in now and getting right around 2 amps each with stock emitters. It’s almost as bright as my L6 which is not bad. I’m looking for that, are you kidding me lumen output. That’s why a bought the SRK V2 FET + 7135 Driver and new emitters for my SRK. I will use the SRK 32x 7135 Driver - V2 in another SRK, I really like this driver. I think it might go well in a 4 emitter SRK. I purchased my 6 emitter SRK about 5+ years ago so its the real one, now trying to find one is hit and miss with all the clones.

The Annual Contest? Please do explain, if you don’t mind.

Each year for the past 4 years there’s been a contest devoted to scratch built lights consisting of two separate types, hand made, and machine made. Basically you can use any of the parts that go into a light but you have to make the host from scratch. It’s a hoot with lots of unique and outrageous participation.