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With Mohgasm gone...where to buy C6 kits?

ApexProxy

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I have gone through this topic in detail on other threads in the past so searches could likely find them. Copper is definitely worth it if you are not concerned by the higher costs.
 

n2stuff

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I have gone through this topic in detail on other threads in the past so searches could likely find them. Copper is definitely worth it if you are not concerned by the higher costs.
I have read most of them. But as far I know nobody has actuality done a test with real world numbers. Take a c6 host and change out the sink only and measure the on/off cycle with temperatures/times.
 

ApexProxy

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We don't need to. Go look at the measured physical properties of each metal and you will see. Those measurments are far more accurate than we could get.
 

grainde

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Well physical properties are all well and good, but a test would be better. There are many variables you are introducing, a side from the physical characteristics of the materials you chose. These also need to be calculated and their effect on the final outcome needs to be determined. Better to conduct and experiment and actually measure it. The on off time data would also be a lot more useful to LPFers than a list of arbitary and confusing values. Yes copper is better, but by how much, how does that actually equate to my on off times...?

Anyway, if you had one of those IR thermometers (with a relatively high degree of accuracy around ± 1°C (Cyparagon's FLIR setup would be ideal), you could actually measure the on off times with two equally constructed lasers with identical thermal paste distribution.
You could then measure on times and cool down times, which would serve as an excellent guide for others. :beer:
 

ApexProxy

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Its probably true that runtime numbers would be easier for a lot of LPFers to use but as you mentioned there are also a lot of variables. In order to test two lasers built with an aluminum and a copper heatsink both heatsinks would have to be carefully machined to create the exact amount of contact to both hosts. IMO, our typical mass produced heatsinks are made with tolerances far too loose to get conclusive measurements. Then, both lasers would have to be built with identically performing diodes otherwise there would be one additional variable to throw the measurements off. Then you would be left trying to compensate the error percentages in your instruments, error due to slight differences in the contact of the heatsink to the hosts, and slight differences in the exact efficiencies of each diode all at the same time.

Basically, this is why I don't throw the numbers of exactly why copper is superior to aluminum and instead I say that its simply superior. To elaborate a little I state that the reason copper is superior to aluminum is that it takes more energy to heat it up per volume by 30% and its faster at moving heat in to the host and away from the diode by 49%.
 

grainde

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Yup I agree, but we are hobbyists and so it doesnt have to be that accurate!;) People wont count seconds correctly either! If we could simply measure how fast the copper heat sink heats up to a specific max temp for a diode, compare that to the aluminium and then measure how long it takes the heatsink to cool to a specific temp, we could give some rough values for the on and off times. Yes we should try to be as accurate as poss with the measurement, but the result should be quoted with a margin of error to account for differences in a build. Obviously the result will only be valid for one type of heat sink/host combo and diode. Additionally, it would only really be relevant for the "hot" diodes that run at much higher currents. Theres not much point in using copper for example in a PHR803T build. ;)

To be honest it would take a fair bit of work collecting data for different diodes, heatsink and host combinations, but one could take the median time representative of your average M140 or 9 mm diode and give a ball park figure. :beer:

Edit: I dont have time at the mo, but once I get things sorted out, I might get hold of some extra diodes and heat sinks and try it out.:)
 
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n2stuff

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That is why I mention JUST changing the heat sink. A round number would be fine with me. If you can say that copper is xx% better at on time but aluminum is better for cool off time. I would be a happy camper:D
 

ApexProxy

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Copper is capable of storing more heat but its also better at transferring heat so it would allow longer duty cycle and it would cool off faster if it stored the exact same amount of heat energy. But then you have to think about the longer the duty cycle the more heat it would be storing so basically the relationship would be pretty linear. If I had to take a guess based on experience and on the raw numbers I would say that copper should allow for 30% longer duty cycles since it takes 30% more energy to make it raise the same amount of temperature and would cool off slightly faster than aluminum because its heat transfer is superior. So either way you look at it, its going to have superior numbers in every way.

Someone might have the time to get numbers on just how much better but I don't lol.
 

EpicHam

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Why did this come to copper v aluminium again???
Didn't we already scientifically proved cooper is superior to aluminium in almost any case?

PS: A problem tho , the interface between the heatsink and the host could become a laminar flow region and impeding the heat transfer??
That I don't know tho.
 

ApexProxy

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The amount of contact between surfaces of a heatsink and host directly effects duty cycle since the better the contact surface is the more you can use the host itself essentially as additional mass for the heatsink. Also, with increased contact surface the heatsink is allowed to transfer the stored heat into the host and then into the air. The problem with a lot of cheap lasers is that the heatsink has very little contact to the host which results in an almost insulation like effect on the heatsink. With copper it takes mroe energy to heat it up and its faster at moving the heat into the host so duty cycle is longer and cool down is faster.
 

EpicHam

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The amount of contact between surfaces of a heatsink and host directly effects duty cycle since the better the contact surface is the more you can use the host itself essentially as additional mass for the heatsink. Also, with increased contact surface the heatsink is allowed to transfer the stored heat into the host and then into the air. The problem with a lot of cheap lasers is that the heatsink has very little contact to the host which results in an almost insulation like effect on the heatsink. With copper it takes mroe energy to heat it up and its faster at moving the heat into the host so duty cycle is longer and cool down is faster.
There is actually a better way to do cooling.

Mount that onto the copper heat sink and let it come into direct contact with the ambient air.


Of course you'll want to add a diode cover and lens cover at the front, but thats easily solved with a cage structure that mounts itself on the front
 

ApexProxy

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IDK about you but I'm talking in terms of heatsinks used in handheld lasers. That might work well for a lab style but its highly impractical for portable. Also, TBH that really doesn't have anything to do with the question on if copper was better than aluminum for heatsinks.

I'm honestly not trying to be mean but the whole thread has been about handheld lasers.
 
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EpicHam

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IDK about you but I'm talking in terms of heatsinks used in handheld lasers. That might work well for a lab style but its highly impractical for portable. Also, TBH that really doesn't have anything to do with the question on if copper was better than aluminum for heatsinks.
because the question of
"aluminium vs copper" has been discussed to death.
Everytime , we have reached the conclusion that Copper is better.
Yet, the same question comes up again and again and again.

We aren't getting anywhere.

This ... however.
Is.
Portable lasers modules should be of good size.
Not necessary lab modules.

Also , you do understand we can miniaturize the heatsink and fan module
 

ApexProxy

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Active cooling has been explored in the past. Thing is it is never really practical. I also like my lasers to look really cool and a fan on the side just would kinda throw it off IMO.
 

EpicHam

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Active cooling has been explored in the past. Thing is it is never really practical. I also like my lasers to look really cool and a fan on the side just would kinda throw it off IMO.
Then you'll be stuck with passive cooling and constantly worrying about the interfacing problem and be stuck with 2-3 min of duty cycle
 

ApexProxy

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Then you'll be stuck with passive cooling and constantly worrying about the interfacing problem and be stuck with 2-3 min of duty cycle
Sorry bro but welcome to handheld lasers XD. I love em as they are. I also buy custom made heatsinks so I don't really have to worry about contact issues and there are also some big ass heatsinks out there that allow from some high duty cycles lol. Obviously some may not mind having a fan stuck to their laser if it means longer duty cycles but not me.
 




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