Another Cree CXA3070 DIY Thread

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CannaBare

Well-Known Member
captainmorgan said:
I've been working and busy with other stuff so I haven't had the time or energy to play with my project until tonight. Got the CXA3070 Z4's mounted to the heatsinks and just need to wire things up.View attachment 3135144
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It looks like the wire holders are hanging off the heatsink. I was also experiencing that problem and stopped while I come up with a solution. Would you say it still fits fine? I am judging by the picture so they might not be hanging off.
 
captainmorgan

captainmorgan

Well-Known Member
OK guy's it was late and I was whipped so I didn't give a full run down on what problems I ran into,planned on doing it this morning.

I didn't try fitting the COB into the holder before I layed out where to drill my heatsinks because I ran out of gloves.
What I didn't notice,was that there was part of the outer ring where the screw holes are that was bent down like it's meant to key into something,there is also a plastic peg that sticks through the holder from the wire connectors.
I positioned the holder so if I decided to add the reflector adapter I had room for the screws and that made the wire connector area hang off the edge,which worked out to be good because of the plastic pegs.
When I went to dry fit the COB in it's holder I noticed the bent down area that would not allow me to screw it down enough.
My solution was to carefully grind off the little bent down keyed area on the holder,didn't have to worry about the plastic peg because it hung off the edge of the heatsink.
The COB has full contact with heatsink so I think it should work fine this way.
Also thought I would mention how I applied the thermal paste,I ran a very small bead of paste from corner to corner forming a X on the COB and then put a dab right at the center. This should make for full contact when evenly tightened down. I also used a non conductive paste.
 

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CannaBare

Well-Known Member
Hmm I wonder if they are supposed to be touching the heatsink then... Ideal could do a better job with its instructions.
 
captainmorgan

captainmorgan

Well-Known Member
CannaBare said:
Hmm I wonder if they are supposed to be touching the heatsink then... Ideal could do a better job with its instructions.
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I watched a video from Ideal and they showed it mounted to a round heatsink with the fins radiating out from a round core like spokes. The video wasn't clear enough to see all the detail but I did notice a few extra wide gaps in the fins. Like I said it looks like it's meant to key into something,it won't allow tightening on a larger flat surface,I worked in a few tool & die shops when I was young so this metal work is familiar to me.
 
Mellodrama

Mellodrama

Well-Known Member
cap'n, I came to an entirely different conclusion regarding those little dimples on the outer rim of the Ideal holders. I haven't discussed this with Ideal's engineers or anything, but I feel certain that Ideal went to the trouble of creating the dimples as insurance. Without those dimples on the outer rim there's nothing to discourage the installer from running the screws all the way down to the heatsink and risking crushing the LED. To me, it looks like Ideal designed their holders to touch the heatsink at those dimples, and nowhere else.

I think that was a mistake to grind them off.

I've built four DIY lights using the Ideal holders. A picture of one of them is attached. Believe me, they're working just fine with the dimples.

This probably won't make any sense to someone who doesn't have an Ideal holder in their hands, but I noticed in capn's ("holder 002.jpg", Post #27) picture that the little white nub on the underside of the wire holder is either contacting, or very close to contacting, the heatsink, even though it's on the slope. On mine, those little white nubs are floating free. They're not contacting anything. And my heatsink remains flat out past the holder, unlike the ones capn's using.

As long as you don't crank the screws down too hard on the ones you modified I'm hoping you'll be OK. But to anyone following this thread - I would strongly advise against grinding the dimples off! They're there for a reason.

OK, that's it for constructive criticism. cap'n, those tiny hex-head screws look very cool. I'm glad to see you didn't use straight-slot screws!

EDIT: I wanted to add that it's helpful to tin your wires before trying to insert them into the Ideal wire holders. If you don't tin them the wires tend to start frizzing before overcoming the spring tension inside the wire holder.
 

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Mellodrama

Mellodrama

Well-Known Member
Here's another CPU/COB DIY, just to give you fellers some more ideas. The copper base on this cooler was too small. I hated to put a piece of metal between the cooler and the COB but I couldn't see any other way. So what you're seeing here is a piece of 1/4" aluminum on the bottom of the cooler. It's being held against the cooler with four little machine screws pulling against a tiny piece of metal that I bent into a channel using a sheet metal brake.

The Ideal holder is threaded onto the 1/4" plate.

I put thermal paste between the COB and the plate, then again between the plate and the heatsink's copper base plate. I'm undoubtedly losing thermal efficiency here, but this COB seems to be running as cool as the others.
 

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captainmorgan

captainmorgan

Well-Known Member
Mellodrama said:
cap'n, I came to an entirely different conclusion regarding those little dimples on the outer rim of the Ideal holders. I haven't discussed this with Ideal's engineers or anything, but I feel certain that Ideal went to the trouble of creating the dimples as insurance. Without those dimples on the outer rim there's nothing to discourage the installer from running the screws all the way down to the heatsink and risking crushing the LED. To me, it looks like Ideal designed their holders to touch the heatsink at those dimples, and nowhere else.

I think that was a mistake to grind them off.

I've built four DIY lights using the Ideal holders. A picture of one of them is attached. Believe me, they're working just fine with the dimples.

This probably won't make any sense to someone who doesn't have an Ideal holder in their hands, but I noticed in capn's ("holder 002.jpg", Post #27) picture that the little white nub on the underside of the wire holder is either contacting, or very close to contacting, the heatsink, even though it's on the slope. On mine, those little white nubs are floating free. They're not contacting anything. And my heatsink remains flat out past the holder, unlike the ones capn's using.

As long as you don't crank the screws down too hard on the ones you modified I'm hoping you'll be OK. But to anyone following this thread - I would strongly advise against grinding the dimples off! They're there for a reason.

OK, that's it for constructive criticism. cap'n, those tiny hex-head screws look very cool. I'm glad to see you didn't use Philips head screws!

EDIT: I wanted to add that it's helpful to tin your wires before trying to insert them into the Ideal wire holders. If you don't tin them the wires tend to start frizzing before overcoming the spring tension inside the wire holder.
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Mell I think you attached the wrong pic,I can't even see the holder.
When I went to dry fit it those dimples created a large gap between the heatsink and the COB and to me it looked like it would have distorted the holder considerably when tightened enough with thermal paste,maybe they were designed to work with thermal pads because that was at least the size of the gap.
 
Positivity

Positivity

Well-Known Member
Interesting..haven't tried screwing anything down yet so can't really help. Take a look next chance I get

Took a quick look. Looks like the holder grabs at 2 points instead of 4...actually kinda rocks in place when held by 2 screws. Seems it doesn't pay much attention to securing it solidly as it does just keeping it in place. Looking at the points where the dimples are, they are just the right length to keep the cob even with the heatsink and just a little room for grease or a pad. Probably take a nice even coat of grease to keep it from rocking too much and leaving a gap. It does look to be better suited to a thermal pad like a coolpad with light 30psi stickiness or cool silver pad with no adhesive but better cooling similar to high quality grease.

Think a nice coat of quality grease with the dimples would work fine...just my opinion and I haven't actually done it yet.
 
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captainmorgan

captainmorgan

Well-Known Member
Mell,I was was very careful about tightening the screws down with very minimal force. They were put on with such little force that I planned on checking them after they were run for a bit. I lapped the heatsinks and checked them for flatness because of the brittle nature of the ceramic COB so I would have to apply a lot of force to crack a COB on a perfectly flat surface,I didn't lap them for a smoother surface.
 
Bueno Time

Bueno Time

Well-Known Member
captainmorgan said:
Mell,I was was very careful about tightening the screws down with very minimal force. They were put on with such little force that I planned on checking them after they were run for a bit. I lapped the heatsinks and checked them for flatness because of the brittle nature of the ceramic COB so I would have to apply a lot of force to crack a COB on a perfectly flat surface,I didn't lap them for a smoother surface.
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How far off of flat were your Alpine 11s when you started sanding? Mine were fairly flat compared to the dell e310 heatsink I used on my first cob cooler which was so far off from flat it took a lot of sanding.
 
Mellodrama

Mellodrama

Well-Known Member
I didn't attach the wrong pictures, I just wanted to illustrate that I had working DIY's. It occurred to me that neither picture was particularly useful to illustrate the discussion at hand, but I didn't take any super-closeup shots during construction. I took a picture just now. Hopefully I didn't burn out the camera's sensor.

The Ideal installation .pdf makes no mention of having to drill holes for the dimples to key into.

http://www.idealindustries.com/media/pdfs/products/instructions/ND_7868-6_50-21_Instructions.pdf

If you think about it, Ideal would want to go to market with a holder that is as easy and fool-proof as possible. It doesn't make sense that Ideal would put out a holder that required their customers to machine little divots in their heatsinks. Every extra step costs money. They didn't build these holders for the home hobbyist, they built them for industrial customers.

To each their own, but I feel very strongly about this. Don't grind the dimples off! I guarantee you that the two white plastic wings will push down on the COB.

Speaking of which, I was wrong about the two little plastic wings not touching the sink. When I wrote that last night I was looking at an Ideal holder setting loose on top of a heatsink. When they're tightened down, the Ideal holders contact the heatsink at 4 points - those two tiny white nubs on the underside of the wire holders, and at the dimples. The two arms extending inward from the wire holders are the only parts that push down on the COB. Somewhere in their literature it says something about no metal contact with the COB itself, so that makes perfect sense.
 

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captainmorgan

captainmorgan

Well-Known Member
Mellodrama said:
I didn't attach the wrong pictures, I just wanted to illustrate that I had working DIY's. It occurred to me that neither picture was particularly useful to illustrate the discussion at hand, but I didn't take any super-closeup shots during construction. I took a picture just now. Hopefully I didn't burn out the camera's sensor.

The Ideal installation .pdf makes no mention of having to drill holes for the dimples to key into.

http://www.idealindustries.com/media/pdfs/products/instructions/ND_7868-6_50-21_Instructions.pdf

If you think about it, Ideal would want to go to market with a holder that is as easy and fool-proof as possible. It doesn't make sense that Ideal would put out a holder that required their customers to machine little divots in their heatsinks. Every extra step costs money. They didn't build these holders for the home hobbyist, they built them for industrial customers.

To each their own, but I feel very strongly about this. Don't grind the dimples off! I guarantee you that the two white plastic wings will push down on the COB.

Speaking of which, I was wrong about the two little plastic wings not touching the sink. When I wrote that last night I was looking at an Ideal holder setting loose on top of a heatsink. When they're tightened down, the Ideal holders contact the heatsink at 4 points - those two tiny white nubs on the underside of the wire holders, and at the dimples. The two arms extending inward from the wire holders are the only parts that push down on the COB. Somewhere in their literature it says something about no metal contact with the COB itself, so that makes perfect sense.
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Mell I'm not trying to argue the point,just stating my observations. I've seen the PDF you just posted but the problem is,it shows a different model with slotted screw holes and no dimples outside the screw holes. They seem to have only one PDF and one video that covers all the models. Here's a good question,why doesn't the one in the PDF have those dimples?
 
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