Anyone know of any individual LED group buys?

[number1gsxxr]

Got my heatsinks in on Thursday and placed the order for the LEDs and mounting stars today.

 

[phalanx]

Did Future Electronics honor the lower price over the phone for the royal blues?

 

[number1gsxxr]

Did Future Electronics honor the lower price over the phone for the royal blues?

Yes they did. Also the Rebel Stars were $0.48 instead of $0.57 each. It's strange how over the phone ended up being a lot cheaper.

 

[phalanx]

Awesome! This is going to be a fun build!

Have you talked to Tricky Mike at all about drilling and tapping the two heat sinks? I have a good sized floor standing drill press and could do it if need be but his Bridgeport is much better.

 

[number1gsxxr]

I haven't talked to Tricky Mike yet but I'll send him a message later tonight. The rebel stars require some type of thermal grease between the star and the heat-sink, correct? I've used Arctic Silver before on computer processors.

 

[DoctaQ]

the arctic silver thermal paste will work fine, just not the two part epoxy if you are drilling and tapping.

if you dont blow the 4 test leds after this build id be interested, i could trade some cree xpe or xr-e, i actually have a couple red xr 7090

 

[number1gsxxr]

What are your thoughts on polishing the heat-sink? It seems some people do it and others don't in the their DIY setups. I guess it's mostly done for ensuring a flat surface to mount to in order to get the maximum thermal transfer.

 

[DoctaQ]

i personally dont, i guess it does cut down the thermal resistance a little bit but we're actually not dissapating a ton of power here

 

[phalanx]

Polishing will give you diminishing returns especially when using a good thermal compound between the star and the sink. I doubt it would be worth doing unless you like the asthetics of a mirror finish on the bottom of your heat sink.

Also, don't forget the 4-40 screws and washers for mounting the stars. As a normal practice you are not supposed to use steel mounting hardware in aluminum threads but since the loads are minimal you can probably get away with it. You could probably get away with using nylon pan head screws which are pretty inexpensive. http://www.fastener-express.com/index.asp?PageAction=VIEWCATS&Category=254

While the heatsink is most likely large enough by itself, you should get some cooling fans to ensure everything stays the right temperature. Large diameter 12V fans that are nice and quiet will work best. The controller I intend to make will have the means to control the speed of DC fans so if you end up with loud ones, it wont be hard to quiet them down.

 

[DoctaQ]

temprature controlled? like diy temp control with the negitive thermal resistor

 

[phalanx]

As of right now they aren't temperature controlled but it wouldn't be hard to add a control loop to handle it.

 

[number1gsxxr]

Excellent. That will save me a step then since the heatsink will be inside a canopy and you'll never see it. I plan on getting a few 120mm SilenX fans. I've used them in computers and they are pretty quiet.

 

[DoctaQ]

i used this bullet shaped silver and orange hard drive cooler i found on newegg, it is silent, and im driving it to a full 12v, and it moves a totally decent amount of air.

 

[number1gsxxr]

Well, Tricky Mike passed on drilling and tapping the heatsinks. He said it would just take him waaaaay to long. Any leads on a CNC machinist and how much it might cost to drill and tap 200 holes?

I found this place in Canton, MA http://www.payneengineering.net/services.nxg but I haven't called yet to see if they could do the work.

 

[phalanx]

Unless you have connections, I can't imagine that any machine shop would be cheap.

When I'm back in the office on Monday, I'll see if we have a tapping machine in our fabrication area. I'd be able to use it if we have one. If not, I do have a good drill press at home!

 

[number1gsxxr]

UPS guy just dropped off the LEDs just now.

 

[phalanx]

That was fast! That means I have to get crackin'! I've been travelling for work and haven't had time to start the drivers even though I have all the parts for the prototypes. Hopefully I can start them this weekend. At some point I will need to get 2 of each color from you for testing purposes (along with the stars).

 

[number1gsxxr]

No rush. My brother put a deposit on a hypermotard at Seacoast Sport Cycle in Derry, NH. So I'm sure I'll be heading up there soon. Candia isn't too far from Derry so I could probably drop the parts off some time.

 

[phalanx]

Shoot me a PM through NESR when you think you will be in that area. If it's on a weekend I can easilly just meet you there.

 

[phalanx]

Here is some good news. My work has a tapping head on one of their drill presses which can turn the 200 hole tapping marathon into a 30 minute job. I can get all the time I need on the machines after work.