210 Upgrade Build with LED Build

[nuclearheli]

Ok, working on it.

Actually today was a back track day. Thinking about what Kress said last night and decided not to go on without some research. So:

1. I called a friend of mine, an engineer at work, today. Explained what was happening and the comments. He said:

- Don't worry about the difference in the thermal coefficient of expansion between the two materials. If it gets that hot you will have much bigger problems to worry about. He claims that in order to get a deformation between the two materials the temperature has to be well outside the range that the LED's will even operate at. He agreed that the choice of "hollow star" material was good for the application.

Not to discount any concerns so I was still worried about it. So I decided to do a worst case test today. I called a friend of mine that has a restaurant. I took one of my linear grid pieces to his place and he put them under the heat lamps that they use to keep the food hot. We had a few beers and about three hours later looked at the piece. The bar was too hot to hold comfortably but was not deformed. It took quite a while to cool down. Everything was fine. I am reasonably convinced that I won't have a problem with the heat.

2. Next suggestion from my engineer friend. He agrees, the G11 has excellent electrical properties but crappy thermal conductivity. His suggestion, bore out the holes to leave about 50/1000" of material. He told me that G11 is really tolerant to machining and I could easily get to those thicknesses.

I actually did and it's pretty cool. First of all after milling out the holes I could hardly hold the material because the back was so hot from the drill. I re-mounted the G11 and all seems good.

Last suggestion he made. Dump the nylon screws holding the G11 on to the Al bar. Use SS. Will help with thermal transfer and will not break down like Nylon under moderate heat. No need to use Nylon screws, the G11 is the insulation.

I got rid of the nylon screws and went with SS.

And lastly, he did agree on the concept, sinking the stars in a recessed hole filled with epoxy after attaching the leads is the safest thing to do.

Thanks for the suggestions, you have made my build even better. Please keep the comments coming.

 

[kcress]

Great!

Nice expansion test too. I'm not an M.E. so I don't get into that enough to know more than that, 'it could be a problem so if in doubt check'. Your test was overly abusive so it would even exaggerate any possible problems. Check that off.

Thermal conductivity... 50 thou still seems pretty restrictive to me. For eons before actual thermal materials were developed we used mica. Thin slices of rock. They had some serious thermal resistance but they were good electrical insulators. Once the real thermal materials came out everyone ran to them because they had way better thermal conductivity while still having high electrical insulation.

How about drilling out the G11 entirely. Holes. Put down little disks of modern thermal insulation in the holes. Screw down your stars right thru them. Then you still have your dams around the LEDs. You can even get pre-cut star thermal pads. I think they even have double sticky ones. You could just 'stick' down your LEDs since you will be epoxying them down anyway.

 

[Cuervo]

You could also do a small hole under the star all the way through the G11 and fill it with thermal epoxy.

Since the G11 is there as an insulator, you really only need it around the outside of the LED star right? (or is this what kcress just said and I misunderstood?)

 

[MosMike]

This will be a nuclear LED fixture

I guess that you will glue the stars to the G11 with Arctic silver?
Do you have those harnesses you mentioned - can you post links or photos ?

I think that Kapton tape has good electrical insulation properties.

 

[mkart]

Any chance you could list your sources for all the LED components? I have the exact tank and am remodeling the room off my kitchen for it. Can't wait to see your finished light since I can already tell you are gonna give me some great ideas.Maybe a basic breakdown of the LEDs your using, how many of each color and so on.

Matt

 

[nuclearheli]

Good morning ALL, Excellent comments and again I am rethinking the G11 holes thanks to you guys. I want to answer each one of you but I think the build is ON HOLD...JUST FOR TODAY, maybe.

Here is what happens when somebody is talking on a cell phone moving through a four lane intersection, realizes they missed the left hand turn they were going to make, cuts across all the lanes right into on-coming traffic.

Wife and I were out for a Valentines dinner. This was my 8 month old Expedition. Wife is fine, some seat belt trauma. Me also but I'm sporting the aftermath of a dislocated shoulder.

Feeling a bit beat up today but still anxious to get back to the build. I will be back to everyone a little later.

By the way, she took out three trucks with this little move, mine and two others. Everyone was "ok" sort of. :furious::furious:

 

[BluScrnOdeth]

Good morning ALL, Excellent comments and again I am rethinking the G11 holes thanks to you guys. I want to answer each one of you but I think the build is ON HOLD...JUST FOR TODAY, maybe.

Here is what happens when somebody is talking on a cell phone moving through a four lane intersection, realizes they missed the left hand turn they were going to make, cuts across all the lanes right into on-coming traffic.

Wife and I were out for a Valentines dinner. This was my 8 month old Expedition. Wife is fine, some seat belt trauma. Me also but I'm sporting the aftermath of a dislocated shoulder.

Feeling a bit beat up today but still anxious to get back to the build. I will be back to everyone a little later.

By the way, she took out three trucks with this little move, mine and two others. Everyone was "ok" sort of. :furious::furious:

excusses....

JK, what a good way to ruin a nice evening. Glad to hear everyone lived at least.

 

[Carriegiesler]

When I see people talking on their stupid phone when driving, on public transit, in the store as their unsupervised kids are going nuts, in general not paying attention to what’s going on around them, because their IMPORTANT conversation can't wait. I wish I could stop these people and shove the phone up their dearer sideways.

I am glad you and your family are okay as well as the others.
Hope you get back to the build soon

 

[nuclearheli]

I can sit around here and watch dumb TV shows while my shoulder throbs, or I can bet back in the basement and continue my build, while my shoulder throbs. I am going with #2.

So with regard to the G11 and stars I am going with the suggestions of kcress and Cuervo. I am going to drill out the holes. I have already ordered thermal adhesive for the stars. The entire reason for the G11 surface was to electrically insulate the stars by creating a non-conductive surface and a "Well" that can be back filled with epoxy after testing the rig. I want to make sure I have no exposed contacts, no creepage and no clearance issues. Drilling out the bottom of the cavity does not change what I set out to do but will give me the conductive surface I need to transfer the heat. The bottom of the star has no electrically conductive components. Objective achieved.

Thanks for the analysis and suggestions. I no longer have to wonder if I will have any heat transfer problems.

 

[nuclearheli]

This will be a nuclear LED fixture

I guess that you will glue the stars to the G11 with Arctic silver?
Do you have those harnesses you mentioned - can you post links or photos ?

I think that Kapton tape has good electrical insulation properties.

Yes, but now given the suggestions of several people here I am drilling out the bottom of the recess. See my last post.

The harnesses are not made yet, only on scrap paper. After I finally get the G11 issues worked out I will be making the harness. Will post everything.

 

[nuclearheli]

Any chance you could list your sources for all the LED components? I have the exact tank and am remodeling the room off my kitchen for it. Can't wait to see your finished light since I can already tell you are gonna give me some great ideas.Maybe a basic breakdown of the LEDs your using, how many of each color and so on.

Matt

I can no problem. Please be patient, I want to get back to the build. But here are some basics. Each LED will alternate on each strip.

68 CREE XR-E Royal Blue
68 CREE XP-G R5 Cool White
Artic Silver Premium Adhesive
Of course the two Thomas Research Drivers listed in the beginning of the thread
Driven by my Apex
60 and 65 degree optics.

I may need more and that is why I am building the wire harness with two extra plugs so I have the ability to add up to two more strips to the fixture without any effort if I need to.

 

[nuclearheli]

Finally done with the four LED bars. Now I can go on to the wiring. The bottoms of the G11 have been drilled out and now the stars will be mounted directly on the Al. I also mounted my wire harness clips on the side of each bar.

 

[BluScrnOdeth]

Looking really good. Just one question though. You said you are using the G11 to insulate the creepage volts and what not, I'm not an electrician (puts handin the air like Nixon), but with removing the insulatioon barier on the bottom allow those creepings to pass through the heatsink to the other LEDs?

 

[MosMike]

BluScrnOdeth
True. Acriche LED stars have 5mm clearance for 220V operation.

But what will the TS use to pot the stars?

 

[nuclearheli]

Looking really good. Just one question though. You said you are using the G11 to insulate the creepage volts and what not, I'm not an electrician (puts handin the air like Nixon), but with removing the insulatioon barier on the bottom allow those creepings to pass through the heatsink to the other LEDs?

There are no exposed contacts on the bottom of the star. The closest contact is the on on the top to the edge. I will implant the stars in thermal adhesive then once wired I am going to fill the G11 cavity with epoxy to completely seal all the exposed contacts. Creepage and Clearance are not an issue without exposed contacts.

 

[BluScrnOdeth]

oh ok, i was thinking that some creepage with such high voltage might get to the backing of the alimunim heat transfer on the LED itself, then transfer to your Heatsink, to the other LED's, figured i'd better ask just in case it may have been overlooked. Sorry for the poor spelling typos, i'm getting tired.

 

[nuclearheli]

Ok Last push of the day. The pain is starting to sink in. I did manage to get one full bar wired ready for LED's. It took a little longer because as usual I changed up on the plan, but it worked out ok.

Here is the business end of every line of LED's. This connector will plug into a wire harness I am making that plugs directly into my LED drivers. You will see that also.

Yes, that is an empty glass of scotch in the picture. Well it was empty, it's full again now. Better than any pain killer you can get.

The wire bundles are wrapped in this stuff, Heli Tube.

Originally I was going to use wire clamps to hold the wire bundle to the rods but that was ugly and not neat. I was able to utilize one of the open channels to tuck the wires neatly inside.

I have two drivers, two colored LED's. So I used white/black for the Cool White, and blue/brown for the blues.

The other three should go pretty quick now that I have a system. Shouldn't take more than 30 minutes for each bar.

But that's all for today.

 

[marc111]

Great!


Thermal conductivity... Once the real thermal materials came out everyone ran to them because they had way better thermal conductivity while still having high electrical insulation.

Put down little disks of modern thermal insulation in the holes. Screw down your stars right thru them.

Kress:

Could you recommend some specific thermal insulators for this purpose and where one can find them.

Thanks,
Mark

 

[Crazy35111]

Can you give the dimensions of your tank, how long are the t-slots, what are your spacing on the crees???

 

[hardin4019]

Very nice, tagging along to see the progress.