Modding the KL4

One of the mods that has been fairly popular lately has been putting a 1W or 3W luxeon into the KL4 and sitting back and enjoying all of that throw and beautiful sidespill.

Thanks to the efforts of CM, we now know that you can actually run a 1W or 3W luxeon in a KL4, with the stock circuit, if you only feed it with 1X123 or a single rechargeable. Some have wanted more flexibility with regard to batteries.

Due to the pioneering efforts of CPF's own McGizmo, it was shown that the stock circuit can be replaced by milling or turning out the center of the stock circuit board and epoxing in a DownBoy circuit. Since I don't have a lathe, drill press, or mill, I tried doing it with a drill and really tore the hell out of the first KL4 that I did. It really seemed to be a waste to have destroyed that perfectly good circuit and have nothing come of it, in my case anyway.

Another concern of mine was heat. On one occassion, while doing a mod, I actually burned myself on the circuit. I thought "Man that's hot." Well, unfounded or not, I got a little concerned about the heat generated by the circuit and it's not having any where to go. Anyway, this is what I came up with. I think that the circuit residing in the ecan and potted with AA epoxy provides for a good thermal path to make sure that the circuit stays nice and cool.





It is a pill of sorts and is a direct replacement for the circuit assembly within the KL4. All you need to do is desolder the leads from the emitter and solder the leads from the pill onto your 1W or 3W emitter. The beauty of this is that you don't destroy your stock circuit board.

Another plus to this is that I made this pill using nothing but hand tools, some sandpaper and a dremel. The materials used for this particular pill are a DownBoy 700, AA epoxy, 22 gauge stranded wire, ecan, 3/8" cut washer and a 3/8" nylon washer. It took me about an hour, not including the time waiting for the epoxy to set.

I have some esinks on the way and will see if I can modify it using hand tools. I'd like to see if I can make a replacement for the stock KL4 heat sink that will work in conjunction with the ecan. It would be great to be able to make an entire pill for the KL4. Then you could go back and forth between the 1W and the 5W setup.

Very interesting!

I'm a bit confused. Do you leave the stock circuit in place and just bypass it with this mod?

Clever Chop! I suspect that Chop is taking out the back end completely and letting this "pill" butt up against the black sink/ can of the KL4?

tyler,
Mc is right on. This completely replaces the entire stock circuit assembly. The overall dimensions are such that it is a direct replacement. The only drawback to this is that it is not self centering like the stock assembly. I haven't gotten to that yet and don't know if I will. It is easy enough to center by eye and tighten the lower portion of the head in place to hold it all toghether. This is the way the stock assembly is held together anyway.

If you can see it, the ring around the ecan's lip is nylon. This made it really easy to take off material and the lower portion of the KL4 just slides over it when tightening without binding.

I did ditch the stock flat sealing ring in favor of an o-ring to get a really good seal. On a KL4 that I tried it out on, it passed the suck/blow test and I haven't sealed it yet with loctite.

The only PITA part of it was taking material off of the top of the ecan. I did this by just making circle with it on a piece of sandpaper and checking it with a dial caliper. When the combined thickness of the lip of the ecan and the top washer was the same as that of the stock assembly, I stopped. The only purpose of the nylon washer is to act as a spacer allowing a friction fit of the upper and lower halves of the KL4 holding the "pill" in place.

If I can get the esink to replace the stock heatsink, I should be able to do away with the washer and nylon spacer all together. I'll see when the esink gets here.

I don't know why I've put so much time into modding the KL4. I just love they way they perform with a 1W or 3W in them. I think that the modded KL4 is exactly what the KL1 should have been.

Very nice Tony. We need to get together some time soon. Rick