Heatsinks for DIY LED lamps

bicit

bicit

Well-Known Member
Dloomis514 said:
I don't see a significant difference in the cost for those items, what do you suppose is the determining factor in purchase?
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The amount of power each sink can displace. If you notice, the 12" profile can cool 8.5 watts passively, but the 7.28" profile can only cool 5 watts passively, and the 10.08" profile can cool 13 watts with a 1" length of heat sink.

Supra- I noticed that your perim values and the surface area values differ by a few inches^2. What's going on there?

I'm really disappointed in the pricing of the 12" profile. I guesstimated it would have been around 4.34, which made it pretty competitive. But a $5 an inch, that's hard to swallow. It's one of the more expensive options at that rate.
 
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Dloomis514

Dloomis514

Well-Known Member
bicit said:
The amount of power each sink can displace. If you notice, the 12" profile can cool 8.5 watts passively, but the 7.28" profile can only cool 5 watts passively, and the 10.08" profile can cool 13 watts with a 1" length of heat sink.

Supra- I noticed that your perim values and the surface area values differ by a few inches^2. What's going on there?
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In the two examples you cited, the cost to dissipate a unit of heat is about the same, so even tho you can get more cooling per inch on the 10 inch unit the cost is proportionately the same as the 7 inch unit. Correct?

So is a deciding factor the length needed and that relationship to how much space is available in the room? And maybe the weight?
 
bicit

bicit

Well-Known Member
Dloomis514 said:
In the two examples you cited, the cost to dissipate a unit of heat is about the same, so even tho you can get more cooling per inch on the 10 inch unit the cost is proportionately the same as the 7 inch unit. Correct?

So is a deciding factor the length needed and that relationship to how much space is available in the room? And maybe the weight?
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also weather or not it's going to be passive or actively cooled. Adjustment options(IE one massive sink vs a dozen small ones). What temperature range is desired. Lighting foot print, since one would have more room to space out emitters on a 12" wide sink vs a 3.5" wide sink. Lots of things to consider when picking a heat sink if you want to take the time.
 
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churchhaze

Well-Known Member
Still looks awesome at 5 dollars an inch. Of course it would be nice if it was less.

The 12" profile looks like it's going to be my new passive veg lamp design. I'm thinking 4 inches long for 20 bucks each. My veg boxes would use 2, so 40 bucks in heatsinks. I'm also considering a similar setup for strawberries since I have an extra veg box I'm not going to need.

12"x4" platform with 31 fins.

My plan is to use 5000k vero 10 or 12 and mix with XP-E photo red. not exactly sure how much power is the perfect amount for those sinks yet. I just know I want them!! lol
 
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AquariusPanta

AquariusPanta

Well-Known Member
This seems like the suitable thread to ask this question: When mounting a COB to a CPU h.s., such as the Arctic Alpine 11 Plus, would one need to simply drill a hole for a slightly thicker self-tapping screw in order for a secure mount?

I've read a bunch of people go about tapping by hand after drilling; I don't know if their talking about with screws or with bolts/with tool tap.
 
Abiqua

Abiqua

Well-Known Member
I've read a bunch of people go about tapping by hand after drilling; I don't know if their talking about with screws or with bolts/with tool tap.[/QUOTE]

There are also thread forming taps and threading forming screws along with hand taps for cutting screw threads and self tapping screws......got it? :)

Slightly thicker than what? the diameter of the hole in the actual cob itself or the suggest diameter [M3] of the mounting hardware?

Aren't you using, Molex connector's too? I would just use kapton to hold them down, unless you have no area to mount tape. I know those sinks can be tricky to mount other things once the cob is actually mounted across the diamater...


I suggest one of these if you ever go to a hand tap/ drill setup :peace:

4/40 Spiral flute bottoming tap....
spiral flute.jpg
 
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AquariusPanta

AquariusPanta

Well-Known Member
@Abiqua

I got a few of those at my disposal. I was thinking of just using the recommended drill bit (2.05mm) with a cordless-screw gun when drilling into the AA11P for a Vero 18 and then fastening the COB with 2x M2.5 self-tapping screws (the ones that cut threads while screwing into the object). Has anyone tried this method before?

I ordered some Kapton tape to try out but screws/bolts would look cleaner imo. I did order some 20 gauge Pico wires for my Veros (all for fun).
 
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Abiqua

Abiqua

Well-Known Member
I've read a bunch of people go about tapping by hand after drilling; I don't know if their talking about with screws or with tool tap.

I got a few of those at my disposal. I was thinking of just using the recommended drill bit (2.05mm) with a cordless-screw gun when drilling into the AA11P for a Vero 18 and then fastening the COB with 2x M2.5 self-tapping screws (the ones that cut threads while screwing into the object)
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Drills are extensions of hand taps, nowadays....I am guessing hand taps have been around for longer than the electric drill. But that is 99% of what people are talking about are hand taps, mounted in a cordless drill or some even use them in a small drill press.

Larger taps you can buy at Harbor freight for instance, I don't think they are necessarily hand taps, just because they don't or weren't meant to fit into hand powered tool, only powered.

There are many "types of taps" but they basically take three shapes:
Taper -Plug - Bottom

Self tapping screws shouldn't be a problem, just some are meant for aluminum and some aren't. Also have you looked at the Vero data, do they say, M2.5? Just curious, not that I am against the norm, especially for something so similar, however. I will stop there, because I don't know what the recommend diamater is, so I don't know if 2.5 is ok, but seems so.

Really I have no opinion on self tapping screws, as I am going to read right now, but they are similar to thread forming screws which are the equivalent of roll taps.

Roll taps work by extruding the metal into the shape of the threads, even cold. They do not cut like a metal tap, but you still have to drill a pilot hole. Supposedly much stronger this way, threads are less likely to break and drill is supposedly quicker because higher speeds are OK. :peace: Thread forming screws are said to work in the same fashion and function the same as self tapping hardware. They do require a different pilot bit size than a normal 4/40 tap, but I do have chart.....maybe its time to start a Diy Drill and Tap thread?

These are readily available in M3 sizes, but i have not looked in others...not spendy.
 
AquariusPanta

AquariusPanta

Well-Known Member
@Abiqua

A DIY thread on COB/H.S. mounting would help out a bunch of people I suppose and could allow countless examples to be demonstrated, which I'm all for.

If someone doesn't get to creating the thread before long, I'll have one drafted in the coming days (as I'll have tested out my proposed method and will be able to share a slice of my experience).


With a few exceptions, Vero10-18 uses M2.5 while Vero 29 takes M3. I took this from the manufactures handsheet. Others have shared success with slightly increasing recommended bolt/screw size.
 
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Tazbud

Well-Known Member
I drilled straight through, m3 hex head machiene screws carefully placed between fins. Is this a bad idea for 'hot-spots'? i'm not sure, never intend to deal with high power/heat anyway. The screws are long enough to take a reflector (and another nut) :eyesmoke: They pulled in tight enough to just use a little socket /extension (by hand) to adjust tension on the cob from below.
 
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bicit

bicit

Well-Known Member
For tapping small holes in soft materials like aluminum I'd advise using thread forming taps, without flutes. I prefer thread forming taps because they don't form chips, and you can just screw the tap straight in. They're just easier to work with IMO. I don't even use lube.

To save on tooling, I'd just go for M3x0.5mm pitch if you're working with the vero series. You can find M3 screws at most hardware stores and even a drill/tap set at home depot.

Something like this is great for doing through holes.
http://www.ebay.com/itm/3mm-x-5-Metric-HSS-Thread-Forming-Tap-M3-x-0-5mm-Pitch-/140875690593?pt=LH_DefaultDomain_0&hash=item20ccd87261

Something like this would be ideal for doing blind holes in thick CPU coolers.
http://www.ebay.com/itm/M3-x-5-D5-Thread-Forming-Bottoming-ANSI-CNC-Tap-HSSE-V3-Vanadium-3-YG-1-Z9205-/151421309161?pt=LH_DefaultDomain_0&hash=item234169d0e9

I'd also advise something like this for keeping the tap straight. It's a rather cheap expenditure considering the price of broken taps in expensive heatsinks.
http://www.grizzly.com/products/Tap-Wrench-w-Fixture/H5607
 
SupraSPL

SupraSPL

Well-Known Member
bicit said:
Supra- I noticed that your perim values and the surface area values differ by a few inches^2. What's going on there?
Click to expand...
It recently occurred to me that the equation was not including the surface area of the cut sides. With the way @churchhaze is planning on using the 12" profile that bit of surface area is significant so I added it in and now the equationss are not so elegant as they once were, but I will get over it :joint:
for inches² =if(I10="cm", I17/6.45, (I14*I15)+(I12*I13*2))
for cm² =if(I10="cm",(I14*I15)+(I12*I13*2), I16*6.45)
 
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