Heatsink
 

I don't suppose anyone knows a good (think cheap) source for a roughly 10"x16" hunk of heatsink / finned aluminum?

Sucks when you realize when you complete a DIY project that your design was wrong from the start. Acrylic is a very effective thermal insulator... I need to get the heat away from the LED lighting I'm going to use on the new 5g tank... :rolleyes: 8 destroyed hunks of acrylic... over 2400 holes marked and drilled by hand and at the end I realize the error of my ways. :redface:

Andy

Have you looked at surplus places like princess auto? or maybe a computer junk dealer? I saw heatsinks and such on sale at princess auto awhile ago... and you could probably pull off old computer heatsinks from old/dead computers. If you were closer, I'd give you a couple of cpu heatsinks I have sitting around.

-Rich

The only heatsinks I've seen at princess were CPU coolers (too small) and welding heatsinks (way too big/bulky).

I've thought of the CPU heatsinks, but about the biggest I've seen is 4", the overall design works for me - but the price for a larger hunk of it from the electronics shops is pretty insane (300-500) I'd go MH before I spent 300$ on a heatsink for my 5g's lighting :)

Andy

where is all the heat comming from?

Steve

The LEDs themselves put out a fair amount of heat. (They aren't quite as "Cool running" as some might have you believe). 300 of them together, will probably warm things up pretty good.

Andy

I have at work a stainless steel tape. It's 6" w and 1/16th thick. We use on helicopters as patch work. I don't know off hand where you can buy it but I'll ask on monday if you are interested. I used some inside my canopy on the side panels, it's not 100% reflective but does the trick. I don't think it's cheap though. If you don't need much I could see if I could barrow some if you know what I mean. :rolleyes:

LMK.

cheers

I know they put out heat, I use them for a lot of things, but they do not get hot enuf to melt plastic. this is why I am asking what else is putting heat there?

Steve

Not worried about them melting plastic... They don't get that hot.

But 300 of the 20,000mcd units in a limited space are going to put out a fair amount of heat. Excessive heat can dramatically reduce the life of the LED, thus I definitely want a material that will wick the heat away.

Andy

I think the best way would be a small fan to blow accross the aray and remove heat from under the hood. a heat sink on plastic isn't going to do anything realy as the plastic is an insulator.

on another note where is the pics of your creation? :mrgreen:

Steve

I would talk to places that build/repair industrial motor controllers or variable frequency drives. I deal with these controllers on a daily basis and they have huge heatsinks. I am sure if you asked for a heatsink from a destroyed vfd you could get a good price, If I lived in Calgary I could probably get you one for free but alas, I am not there.

Fan will be encorporated. But, if the plastic casing gets warm, (which it does) then the heat sink will work nicely. It will sure beat the acrylic I was going to use - as the acrylic effectively trapped the heat against the LEDs.

Pictures? do you want pictures of a pile of LEDs and resistors? Or of the broken shards of acrylic? :mrgreen:

I'l have some pictures coming in due time no worries.

Andy

oh are you going to mount the LEDs directly in the heat sink material. I though you just wanted to atach it to the plastic hehe.

how did you break the plastic?

Steve

Yes, the plan was to use it as a place to mount - and source of heat removal :) (maybe not the brightest idea exposed wires and aluminum and all - but I figure I can use some liquid electrical tape where needed and make things safer)

Drilling the acrylic, it seemed like if I breathed wrong i'd end up with a nice crack running from hole to hole to hole.... Of course, I would probably have had better success with a different bit, and the use of some lubricant. But hindsight and all...

Andy

you have to turn your drill bit into an acrylic bit, can't but them that I have seen but they are easy to make. you have to grind the two cutting edges flat so it doesen't try to pull through the plastic. I have to do a big bit today so I will take befor and after pics.

Steve

Steve, think a Brad point bit would cut acrylic better than a normal bit? Back in the day I was drilling pieces of foam (weatherstripping type stuff) and I found a Brad would evenly slice a nice hole rather than chew in and pull the foam apart.

My problem working with acrylic has always been having it melt on me. Too high RPMs, maybe?

hole saws melt plastic, a brad point doesent work good, tried it, but a forsner does work. the best is a modified normal drill bit.

Steve