# Trimming Cree MCPCB's for the Aleph XR can



## TranquillityBase (Dec 13, 2007)

This is the cure for Cree XR-E MCPCB emitters that are *off center*...I personally haven't had one that has been close to centered, rounds or stars. 

The first experiment was turning the MCPCB down to .680"...*Don't gasp*...I chucked directly to the metal ring that surrounds the emitter, and then set a live center against the back of the MCPCB, using a small piece of plastic as a buffer between the live center, and the MCPCB...After the MCPCB is trimmed, the emitter will be *dead nuts* centered, or about as good as it gets (the metal emitter ring isn't exactly concentric to begin with)

I thought about making a holding fixture, but chucking directly to the emitter ring has worked out fine.

The XR can was bored to .681, so the MCPCB has slip-no-slop fit, to the XR can.

Make sure to chamfer the perimeter of the MCPCB, so only the aluminum core touches the bore of the XR can.

Centered emitter, *easy* solder points, and all packaged in a standard Aleph XR can...:twothumbs


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## PEU (Dec 13, 2007)

TranquillityBase said:


> I thought about making a holding fixture, but chucking directly to the emitter ring has worked out fine.



Brave guy, you are. Yes, hmmm... <yoda voice> 


Pablo


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## TranquillityBase (Dec 13, 2007)

PEU said:


> Brave guy, you are. Yes, hmmm... <yoda voice>
> 
> 
> Pablo


Cree XR-E's are very durable LEDs


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## tino_ale (Dec 14, 2007)

TranquillityBase said:


> *Don't gasp*...I chucked directly to the metal ring that surrounds the emitter


Eventhough you warned, I did gasp :hahaha:

Scott you are one of the few who really pay attention to such details (dead centered led and such) and I must say... I LOVE IT :wave:


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## TranquillityBase (Dec 14, 2007)

tino_ale said:


> Eventhough you warned, I did gasp :hahaha:
> 
> Scott you are one of the few who really pay attention to such details (dead centered led and such) and I must say... I LOVE IT :wave:


Thanks tino...

I love the XR-E, but the MCPCB's are horrible, as far as centering...This method is a great fix, and soldering to the MCPCB pad is a breeze.


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## jch79 (Dec 14, 2007)

*T*otally*B*onkers-

Nice job... you were able to do a star too, eh? :naughty: SWEET! :rock:

So now you don't have to solder to the LED - you can have the nice big ol' pads to solder to! :thumbsup:

john


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## TranquillityBase (Dec 14, 2007)

jch79 said:


> *T*otally*B*onkers-
> 
> Nice job... you were able to do a star too, eh? :naughty: SWEET! :rock:
> 
> ...


 
Yep...easy soldering, and plenty of room for leads as thick as 24 gauge


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## cmacclel (Dec 14, 2007)

Your nutz!

My relationship with Cree LED's is a Love / Hate relationship I Love the brightness but aboslutely hate the way the glass lenses are attached. Some of these glass lenses are barely attached from the factory. If you touch them with Isopropanol Alchohol (or sometimes even the wrong way) the adhesive will give way and the glass leses will usually become detached 

Mac


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## LED Zeppelin (Dec 14, 2007)

Nice trick TB!

I've found the Crees very durable in some aspects - resistance to soldering heat, and the strong metal ring, but the domes are a pain. I've unpacked several new ones that have partially adhered domes with an air pocket ring under them. And the Vf can be up to 0.5V off from one to the next.

But once you get a matched set installed, they're great.


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## jch79 (Dec 14, 2007)

Mac & LZ-

Out of curiosity, who is the supplier of the Cree's with bad domes you've been getting - because everything I've bought from Cutter has been perfect. :shrug: Granted, you guys probably buy much (much!) more than I, but I've never had a problem. 

 john


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## TranquillityBase (Dec 14, 2007)

> cmacclel said:
> 
> 
> > Your nutz!
> ...


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## X_Marine (Dec 15, 2007)

Great job on the pcb's. :thumbsup:

I recently learned the sore spot of a Cree after mounting and lightly clamping with rubber, not a good idea without a protective sleeve to press only on the ring.

Hmm?? what is this stuff oozing from around the lens.. lol doh! :tinfoil:

Is there any hope for replacing the lens are is it just destined to a very low output application that won't suffer from a distorted lens.

Thank goodness I have extras..

ThanX
X..


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## LED Zeppelin (Dec 15, 2007)

jch79 said:


> Mac & LZ-
> 
> Out of curiosity, who is the supplier of the Cree's with bad domes you've been getting - because everything I've bought from Cutter has been perfect. :shrug: Granted, you guys probably buy much (much!) more than I, but I've never had a problem.
> 
> john



John, I bought maybe 10 (Q4 WH?) from NitroZ, of which one had a defective dome.

I also bought maybe 70 from Endeavor, and have used about 20 of which one had a defective dome, and one was DOA. The other 50 are still wrapped.

The 18 or so Q5 WC & WH I received from Erasmus were okay, but I only got to use about 10. The rest were inadvertently throw out with the garbage, AARGH.

I've also sampled about a dozen Cree stars from DX and Kai, those domes were all okay even though they were not in factory packaging and not particularly packaged well for shipping.


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## jch79 (Dec 15, 2007)

Cool - thanks Dennis! :thumbsup: :shrug: Well, it's a different kind of LED lottery now than the ol' LuxIII days! :laughing:

john


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## cmacclel (Dec 15, 2007)

LED Zeppelin said:


> John, I bought maybe 10 (Q4 WH?) from NitroZ, of which one had a defective dome.
> 
> I also bought maybe 70 from Endeavor, and have used about 20 of which one had a defective dome, and one was DOA. The other 50 are still wrapped.
> 
> ...



I purchased 90 from Erasmus and they where all fine. The VF on that batch averaged 3.3v vf at 600ma.

The next batch of 50 I purchased from Endeaver had a VF average of 3.6v and had 2 bad domes.

The latest batch I purchased from Endeaver was for a few Sceptre's I need to build but due to the higher VF I can't use them 


ZEP  I through out 7 from Erasmus inadvertently! They must be cursed 

Mac


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## LED Zeppelin (Dec 15, 2007)

cmacclel said:


> I purchased 90 from Erasmus and they where all fine. The VF on that batch averaged 3.3v vf at 600ma.
> 
> The next batch of 50 I purchased from Endeaver had a VF average of 3.6v and had 2 bad domes.
> 
> ...



Lol Mac! Indeed they must be cursed. But they did have a lower Vf as you mentioned.

The ones I've been using from Endeavor are brighter according to my Lux meter, but the Vf is higher. The 20 I measured an average of 3.3 - 3.4 V @ 350 mA, one was exceptionally low @ 3.0 V, and some at 3.5 V.

I forgot to mention that I did buy some Crees, maybe a dozen, from Cutter and all those were fine.


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## Ty_Bower (Jan 25, 2008)

TranquillityBase said:


> The first experiment was turning the MCPCB down to .680"...*Don't gasp*...I chucked directly to the metal ring that surrounds the emitter, and then set a live center against the back of the MCPCB, using a small piece of plastic as a buffer between the live center, and the MCPCB...



I'm assuming you used a lathe or some other kind of machine shop tool. I don't have one of those, and I don't even know what a live center is (although I can probably make a decent guess).

Does anyone think there is any chance of success if I just chuck the thing in a variable speed drill and hold it against a flat file? It'd be nice to know if there is a way to make this work for those of us with nothing more than common household power tools.


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## TranquillityBase (Jan 25, 2008)

Ty_Bower said:


> I'm assuming you used a lathe or some other kind of machine shop tool. I don't have one of those, and I don't even know what a live center is (although I can probably make a decent guess).
> 
> Does anyone think there is any chance of success if I just chuck the thing in a variable speed drill and hold it against a flat file? It'd be nice to know if there is a way to make this work for those of us with nothing more than common household power tools.


Lathe is correct.

The live center supports the back of the MCPCB, so the star, or round is fully supported.

I'll try and load a pic of the set-up later today.

I'm sure any method would work, but the metal ring, that surrounds the emitter, is all you would be gripping, so be very, very careful. 

TB


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## TranquillityBase (Jan 25, 2008)

I now use a small piece of aluminum rod, between the live center and the MCPCB.


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## cmacclel (Jan 25, 2008)

You just wanted to show off your $1000 chuck 

Mac


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## Mirage_Man (Jan 25, 2008)

cmacclel said:


> You just wanted to show off your $1000 chuck
> 
> Mac



Yeah, now I have chuck envy .


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