M-CE in Surefire U2 howto

Hi.
i want to put new life into my trusty U2.
Can you point me to the therad with guide, maybe someone did that before.
Thank you, Mike

I did it.. took forever to get the focus right and ended up taking it apart.

I ended up buying a new U2a head and enjoying it in stock form.

Unless you have a mill. It's not easy to do.

Justin Case said:

https://www.candlepowerforums.com/posts/2666166

Click to expand...

Damn you, Photobucket!

Here you can get some hints.







Not easy to open the head and machining work is needed.

Can I mill reflector without removing from the head?
What is milling diameter?
Thanks for replys
Mike

sp5it said:

Can I mill reflector without removing from the head?
What is milling diameter?
Thanks for replys
Mike

Click to expand...

About 13mm diameter with lathe, I think lathe is better than mill for this work.
There is no separate reflector. So you have to disassemble the lower part of head, not bezel ring.

The case dimensions for a Cree MC-E are 7.5mm x 7.0mm. The stubby little MC-E terminals extend the size to 9.0mm x 7.0mm. The dome diameter is 6.36mm. So you'd probably want to remove enough material for the MC-E case to sit flat and flush with the bottom face of the reflector and have enough clearance for the little terminals as well.

In the link I provided previously, the mod'er used a Dremel with a 1/8" carbide burr with a flame shaped tip to do his "carving". So it can be done without a mill or lathe. Darkzero also has used a Dremel to do similar mods.

In Post 54 of the link I provided, AaronM says:

"I found the ideal spacer height for the KL4/MC-E combo: 1.8mm! You'll have to mill the emitter pocket at the back of the reflector 0.35mm to make it work.

The perfect spacer for the U2 looks to be about 2.5mm high and the deepest part of the emitter pocket needs needs to go deeper by about 0.25mm."

I used a die grinder and a carbide cutter on mine.

I have head open, that's no problem. I have a friend with lathe and knowlegdge how to use it

So let's get all together to avoid mistakes:
1. Depth - 0.35mm
2. Diameter - 13mm
3. Spacer thickness. 1.8mm
4. Led connection (series/paralel)
Am I right?
Mike

If you are mod'ing a U2, AaronM's post suggested a spacer height of 2.5mm and machining the back of the reflector to a depth of 0.25mm. Also, this might result in increasing the diameter of the reflector opening. I would be careful to avoid increasing the opening size too much. You want the LED's dome to come through, but probably not the entire LED case. If the case fits entirely through the reflector opening, then you will have to do something about insulating the MC-E's terminals to avoid shorts against the exposed metal of the machined reflector face.

Does the U2 use a Luxeon V? If so, then you want to wire the MC-E in 2S2P, assuming you plan to re-use the stock driver.

Yes, stock driver.
How to kep together led, spacer and original housing? Glue them or it will keep all together after assembling the light under head pressure.
Mike

You will never get all those pieces to stay together by depending on friction alone. Also, you need to maximize thermal conductivity through all of the various contact interfaces. The MC-E is going to generate a fair amount of heat and you need to remove it from the LED or it will cook itself.

The easy route is to use Arctic Alumina thermal adhesive to glue the spacer to the heat sink and then the MC-E to the spacer. You could also use Arctic Silver thermal adhesive instead.

What I did for my SF KL4/MC-E mod was to use Arctic Alumina thermal compound between the LED and copper spacer, instead of AA thermal adhesive. That way I could then drop the works into the reflector to self-center the LED. I then carefully removed the LED/spacer/heat sink combo from the reflector and used regular epoxy to secure the LED.

I think, I'm gonna make new heatsink.
What about batteries?
Will this work from 18650 as before or I have to use 2xCR123?
MIke

The U2 uses a Luxeon V LED, correct? The whole point of using an MC-E in 2S2P is that in terms of Vf, the MC-E will look almost exactly like the Luxeon V. Thus, whatever the Luxeon V can use for batteries, so can the 2S2P MC-E.