# P7 O-sink interest



## yaesumofo (Apr 6, 2008)

HI guys I was wondering if there is any interest in an O-Sink for the P7 emitter?
I have yet to see one in person but If there is sufficient interest I will embark on research and development program and will get some sinks made.

I understand the P7 runs HOT and needs great heatsinking. I could design the sink to extend deeper into the body adding mass to the sink which would be hidden inside the body of the light.... The Mag host is a natural. I don't know what the beam will look like I suspect that an aluminum reflector may be called for if the P7 is driven at it's max.
The 3 cell mad may be right for direct drive...
Ideas thoughts? welcome...

Yaesumofo


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## 2xTrinity (Apr 6, 2008)

I'd be interested in one. A 2- or 3-c P7 light would be nice for sure, a great blend of runtime and output.



> ]I understand the P7 runs HOT and needs great heatsinking. I could design the sink to extend deeper into the body adding mass to the sink which would be hidden inside the body of the light.... The Mag host is a natural. I don't know what the beam will look like I suspect that an aluminum reflector may be called for if the P7 is driven at it's max.


Nah. Aluminum reflectors are needed because incans emit most of their input power as IR radiation, which is largely absorbed by the reflector. Even at 900lm, this will probably heat the reflector less than a stock mag bulb as ALL the light is in the visible range (unlike the mag where most isn't). With LEDs, most of the input power must be conducted away using heatsinking.


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## Supernam (Apr 6, 2008)

I played with the P7 AA'd to a DHS "D" size sink. It was not attached to the body, but rather in a test configuration. However, after about 20 seconds direct driven, the sink got too hot to hold with a firm grasp. Surely if it were in the Mag body, it would dissipate heat better, but this just gives you an idea of how hot it gets.

The extended o-sink would be great, but make sure it doesn't go too long as to inhibit the use of drivers. I'd say there should be about .5" space between the bottom of the sink and the top of the switch. I think a possible design modification would be to make a heatsink similar to those that use multiple emitters. That is, one that has a large platform that fills up the inside of the head instead of just plugging into the body. This would ensure that heat is efficiently transfered directly from the emitter to the outside of the head. Most of the multi emitter sinks have a hole in the middle so they wouldn't work, also there would need to be a post for the emitter to go into the reflector. 

It'd be a good idea to use thermal grease to lube the threads of the Mag head and the body to have efficient heat transfer between the two parts. I believe a finned mag head would significantly increase surface area for more effective heat dissipation. 

I'm currently waiting for parts to come in to complete a Mag 4C Nimh using a DHS sink. It'll be running at 2.8A (realistically 2.4A) I'm worried that the C mag has slightly less mass than the D mag to dissipate heat. I'll definitely fin this Mag's head. I'll be locking the head in place after finding the best focal point, so I'll use Arctic Silver to "glue" the threads.


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## Supernam (Apr 6, 2008)

2xTrinity said:


> I'd be interested in one. A 2- or 3-c P7 light would be nice for sure, a great blend of runtime and output.
> 
> 
> Nah. Aluminum reflectors are needed because incans emit most of their input power as IR radiation, which is largely absorbed by the reflector. Even at 900lm, this will probably heat the reflector less than a stock mag bulb as ALL the light is in the visible range (unlike the mag where most isn't). With LEDs, most of the input power must be conducted away using heatsinking.



I agree that aluminum reflectors are not necessary with LED's, however it is preferred that one uses a textured reflector since the emitter's surface is so wide. I wouldn't mind using the a plastic reflector if there were some kind of orange peel to it. I'm going to try using clear spray paint on a stock Mag reflector and report my findings. I have a FiveMega MOP reflector that I'm going to enlarge the hole. It might be easier to buy the KaiDomain 15mm opening MOP reflector though.


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## gojira54 (Apr 6, 2008)

Hello :0)
I've been lurking this forum for a while!
I'm definitely going to P7 mod a [email protected] 3D direct drive. I've seen that there are gonna be heatsinks available from a couple of sources in the dealers corner in the near future but none of them look like they are out to maximise heat dissipation for a direct drive application. I think it's a great idea to make the sink as chunky as possible!
I'll be in for a few if these get made :thumbsup:


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## ambientmind (Apr 6, 2008)

I think an o-sink for c and d mag lights would generate great interest. I know I'd be in for one of each, I actually need one right now for a c sized mag.


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## DFiorentino (Apr 6, 2008)

Count me in.

-DF


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## yaesumofo (Apr 6, 2008)

I will look into it. In this day and age of cheap Chinese flashlights coming out left right and center it is difficult to make a product which can compete. Lucky for us they don't concentrate their efforts on accessories and modification parts. What is crazy is that places like DX have complete P7 lights available for sale for under $50.00!!
The idea of modding a mag to accept a P7 is not new. Several people have already done it.
What may end up being new is the heat sink used to to the mod.
I have found that the space inside the Mag body behind the space that is created when a O-Sink is mounted is Huge!! There is plenty of room in there for more aluminum in the form of an extended sink and a driver. IMHO the driver should be mounted into the sink as well so that heat generated by the driver may be efficiently moved.

My fear is that there is simply TOO MUCH heat generated by the P7 to efficiently move it using a passive heat sinking system.
These emitters make a lot of heat. even with the mass of the head being thermally well attached to the body of the light there is a lot of heat to move.
The idea of three P7's running at full power ..I see a light which may not be usable for more than a few minutes...


My focus is on creating a sink which will allow a P7 to be mounted inside a Mag host for it to move heat efficiently enough to allow for continuous use of the light.... Maybe copper? I hate using copper because it is so yummy to machine....then then there is the issue of cost...copper is pricey especially if you choose to use the tellurium copper. I would be buying 8 foot lengths of material. Buying less is silly due to the machine shop minimums...
1 1/2 inch 8 foot length of 7075 costs $130.00
6061 is about 1/2 the cost of 7075...
the same thing in copper costs over $900.00

A copper O-sink will cost 7 or 8 times as much as an aluminum unit. I material cost alone. WOW!!

So anyway I think I will focus on 6061 for the sake of those of you who are budget minded. IN the past an o-sink cost the end user $10-$15.00 if memory serves me. I suspect that material cost have gone up since I made those as well as the cost of machine time ...everything has gone up.
Research is needed. I am unwilling to do a lot of work on a product with an extremely limited market. 
Unfortunately on the surface of things it looks to me as though I may not be making these. there is good size investment required and the market for this part is not what I would call booming.
If you guys have ideas which can help make this idea become a reality please share them with me.
As I said I will do the necessary research to learn about the feasibility of mounting the P7 onto a hunk of aluminum in a Mag host.
Any info you guys feel like sharing regarding this please post.
Yaesumofo


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## Meduza (Apr 6, 2008)

Of course i would be in for one


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## Supernam (Apr 6, 2008)

Yaesumoso,

I am wondering if it would be a better idea to mount drivers separately than the emitter's sink. I suppose it would depend on what driver/battery combo you are using, but suppose one was using 3 or 4 nimh's with a driver for the P7. The Vbatt and Vf are so close that it shouldn't create that much heat. I believe the the emitter/sink temp would be much greater than the driver. 

I'll be mounting my AMC7135's right above the switch by AA'ing them to the body (with the chips touching the body). I think that the heat from the emitter will mostly conduct outwards through the head so the temperature of the body just above the switch will be cooler than the sink. 

Regarding the copper sink... I'm no physicist, but I wonder if it would actually help significantly to use a copper sink. While the heat would conduct away from the slug faster, it would still encounter the barrier of the aluminum body which would have to then conduct through body's threads onto the head's thread then though the head itself to its surface. Not to mention that there is a coating of anodizing through each of the surfaces. Certainly a copper sink would help, but the question is, by how much? And considering that the cost would be nearly 10 times more, would it be worth it? 

Again, I'm no pro, but I think it is important in this type of set up to get the heat from the slug to the air as efficiently as possible. I will try to do so in my own set up by stripping anodizing from inside of the body and also AA'ing the threads. Finning and/or fluting the head would also greatly increase the surface area of BARE aluminum to the air.


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## PhotonFanatic (Apr 6, 2008)

Supernam,

You seem to imply that anodized AL will not conduct heat as well as bare AL. Can you point me to any published data showing that to be the case? Thanks.


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## Supernam (Apr 6, 2008)

I cannot. I am only assuming that it doesn't. 

I am assuming that, although minute, anodizing has _some_ thickness to it or at least alters the surface which may have less thermal conductivity than an aluminum to aluminum contact.


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## Supernam (Apr 6, 2008)

From wikipedia (http://en.wikipedia.org/wiki/Anodising): "Anodized coatings have a much lower thermal conductivity and coefficient of linear expansion than aluminium. As a result, the coating will crack from thermal stress if exposed to temperatures above 80 °C. The coating can crack, but it will not peel.[5] The melting point of aluminium oxide is 2050 °C, much higher than pure aluminium's 658 °C.[5] (This can make welding more difficult.) In typical commercial aluminium anodization processes, the aluminium oxide is grown down into the surface and out from the surface by equal amounts. So anodizing will increase the part dimensions on each surface by half of the oxide thickness. For example a coating that is (2 μm) thick, will increase the part dimensions by (1 μm) per surface. If the part is anodized on all sides, then all linear dimensions will increase by the oxide thickness. Anodized aluminium surfaces are harder than aluminium but have low to moderate wear resistance, although this can be improved with thickness and sealing."


Others:

http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA191755

http://www.frostytech.com/articleview.cfm?articleID=233

http://www.finishing.com/3200-3399/3207.shtml

Assumptions ended up proving true.


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## PhotonFanatic (Apr 6, 2008)

Thanks and right you are.

This chart is quite helpful:







I'd love to make some silver heat sinks, but for a P7 it might be a tad prohibitive--a 1' length of 1.25" diameter coin silver rod sells for $2,374.00. :devil:


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## cmacclel (Apr 6, 2008)

Supernam said:


> I agree that aluminum reflectors are not necessary with LED's, however it is preferred that one uses a textured reflector since the emitter's surface is so wide. I wouldn't mind using the a plastic reflector if there were some kind of orange peel to it. I'm going to try using clear spray paint on a stock Mag reflector and report my findings. I have a FiveMega MOP reflector that I'm going to enlarge the hole. It might be easier to buy the KaiDomain 15mm opening MOP reflector though.


 
Sputtering the reflector helps but you will not completely smooth the beam out. The MOP reflector will work about the same as the Stock plastic reflector sputtered. A medium stipple reflector smooths the beam out perfectly on the P7.

Mac


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## ace0001a (Apr 6, 2008)

cmacclel said:


> Sputtering the reflector helps but you will not completely smooth the beam out. The MOP reflector will work about the same as the Stock plastic reflector sputtered. A medium stipple reflector smooths the beam out perfectly on the P7.
> 
> Mac



Good piece of info to know Mac, but I would've thought an Orange Peel reflector would still offer a smoother beam than the stock one. I've tried the heavily sputtered reflector I got from Malkoff Devices and it did totally smooth out the beam, but how much output was compromised I don't know...it was still really bright. KD seems to be out of their MOP reflectors at the moment and I've been told they're working a reflector that will work well for the P7. The Sandwich Shoppe has some Modamag Camless reflectors in stock and they offer hole enlargement...but for a quantity flashaholic myself, $30 is alot to drop for a single reflector...and considering I'd want more than one. So that leaves sputtering your own reflector to be the most economical.

As for a P7 O-sink, I believe H22A is going to have a P7 DHS heatsink available next month. The one I did, I just modified and used a standard DHS heatsink and it worked just fine...the heat transfers well to the Mag body and to the touch, only gets warm and not hot.


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## ambientmind (Apr 6, 2008)

yaesumofo said:


> I will look into it. In this day and age of cheap Chinese flashlights coming out left right and center it is difficult to make a product which can compete. Lucky for us they don't concentrate their efforts on accessories and modification parts. What is crazy is that places like DX have complete P7 lights available for sale for under $50.00!!
> The idea of modding a mag to accept a P7 is not new. Several people have already done it.
> What may end up being new is the heat sink used to to the mod.
> I have found that the space inside the Mag body behind the space that is created when a O-Sink is mounted is Huge!! There is plenty of room in there for more aluminum in the form of an extended sink and a driver. IMHO the driver should be mounted into the sink as well so that heat generated by the driver may be efficiently moved.
> ...



the only thing i can think of to make this simple and cost effective is to make a heatsink similar to H22A's but instead of milling out the inside of the bottom, leave it solid aluminum to add mass. Also, you could probably make it about 1/2" longer to add even more mass and surface area to move the heat into the body of the light. I was also thinking you could coat the aluminum heatsink with a thin layer of copper, if thats even possible. That might further help the transfer of heat between the led to heatsink, and heatsink to body. But that would totally depend on cost and if its something that can even be done. That step could obviously be skipped. Just my $.02.


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## CM (Apr 6, 2008)

yaesumofo said:


> ..I understand the P7 runs HOT and needs great heatsinking. I could design the sink to extend deeper into the body adding mass to the sink...



I'm really glad someone is paying attention to the heat issue. I've seen so many posts from people who want to put the P7 into a small 2x123 light, drive it at spec, and expect it to perform. 

Whatever you do, please make sure you leave plenty of room for a regulator. I'm not talking about those cheap DX or KD linear regulator, but proper switcher(s). For example, using three Downboys in parallel.

It's a pity that the LED's anode is not isolated. If it was, I would probably remove the anodizing from the inside wall of the [email protected] so as to have a better metal to metal contact. With that and an extended heat sink, one can drive the LED to spec and have the heat properly dissipated onto the body.


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## 2xTrinity (Apr 6, 2008)

> Regarding the copper sink... I'm no physicist, but I wonder if it would actually help significantly to use a copper sink. While the heat would conduct away from the slug faster, it would still encounter the barrier of the aluminum body which would have to then conduct through body's threads onto the head's thread then though the head itself to its surface. Not to mention that there is a coating of anodizing through each of the surfaces. Certainly a copper sink would help, but the question is, by how much? And considering that the cost would be nearly 10 times more, would it be worth it?


In the case of the interior surfaces, It might be beneficial to sand away the anodizing, then polish the sanded bare-aluminum surface, then glue the heatsink directly to the aluminum with epoxy. One less interface to worry about compared to gluing the heatsink to the anodize.

As far as the exterior surface, in that case, the anodizing could actually help as anodized aluminum is an almost ideal radiator, while bare aluminum is pretty terrible (good reflector = bad radiator). At the temps the flashlight will probably reach, radiation could well be a significant method of heat dissipation.

Another variable I haven't seen mentioned so far is that copper has about 50% more heat capacity than the same volume of aluminum (See Specific Heat Capacity), meaning it can "soak up" more energy before increasing in temperature. Taking that into consideration, brass may be another viable option as it has almost the same heat capacity as 100% copper. The greater heat capacity of the brass would almost certainly be cancelled out by the poorer conductivity, though.



> It's a pity that the LED's anode is not isolated. If it was, I would probably remove the anodizing from the inside wall of the [email protected] so as to have a better metal to metal contact. With that and an extended heat sink, one can drive the LED to spec and have the heat properly dissipated onto the body.


Just insert your batteries so as to have a positive ground. Negative ground is just a convention, not a law. A custom rechargeable pack might be a good idea to prevent someone frying your light by trying to put the batteries in the "right way" though.


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## darkzero (Apr 7, 2008)

cmacclel said:


> Sputtering the reflector helps but you will not completely smooth the beam out. The MOP reflector will work about the same as the Stock plastic reflector sputtered. A medium stipple reflector smooths the beam out perfectly on the P7.
> 
> Mac


 
If you sputter it enough it will smooth out the P7 pretty good. I have some left overs that I sputtered too much which I did not like how the beam was with LuxIIIs. But they work good for the P7. 

I've sputtered so many Mag reflectors in the past that I've learned how to sputter them frim light to heavy.

Old threads/pics here:
https://www.candlepowerforums.com/posts/492893#post492893
https://www.candlepowerforums.com/threads/43577&highlight=sputtered


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## darkzero (Apr 7, 2008)

CM said:


> I'm really glad someone is paying attention to the heat issue. I've seen so many posts from people who want to put the P7 into a small 2x123 light, drive it at spec, and expect it to perform.
> 
> Whatever you do, please make sure you leave plenty of room for a regulator. I'm not talking about those cheap DX or KD linear regulator, but proper switcher(s). For example, using three Downboys in parallel.
> 
> It's a pity that the LED's anode is not isolated. If it was, I would probably remove the anodizing from the inside wall of the [email protected] so as to have a better metal to metal contact. With that and an extended heat sink, one can drive the LED to spec and have the heat properly dissipated onto the body.


 
I took a Hotlips-C, milled the pedastal off, & threw a P7 on there. Ran it DD on 3 NiMh. On fresh cells it pulls 3A then drops off to 2.8A quickly. Running it for a few minutes starts to get the MagC pretty warm. Using thermal grease between the Hotlips & the Mag body also helped a great deal in dissapating heat. Having a beefier heatsink is defintely a great idea & I'm in for some too.

I isolate SSC slugs with a very thin layer of epoxy mixed with a good amount of alumina oxide powder, as thin as I can get it. After it dries, I then epoxy the emitter to the heatsink using the same mixture. With P4s I'm not concerned but with the heat of P7s I'm not sure how good the layer of thermal epoxy transfers heat. Well the body of the Mag gets pretty warm so I know it's ok somewhat.

I have these ceramic waffers that measure .025" thick. It's the same material the cree xre bases are made out of but just a tad bit thinner. Can I use these as isolators? I know ceramic withstands heat pretty well but is ceramic a good conductor for heat? Isn't alumina oxide some type of ceramic powder? I tried googling but couldn't find a definte answer.


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## CM (Apr 7, 2008)

Ceramic is a good thermal conductor. Aluminum oxide is a ceramic material. I think the epoxy mixed with Aluminum oxide is a good way to isolate the slug.


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## PhotonFanatic (Apr 7, 2008)

I fail to see why you wouldn't just use Arctic Silver Thermal Adhesive. A tube goes a long way, it's already mixed for you, it uses silver, and it works. 

And it only costs $14.25. :devil:


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## Mel_PL (Apr 7, 2008)

darkzero said:


> I isolate SSC slugs with a very thin layer of epoxy mixed with a good amount of alumina oxide powder, as thin as I can get it. After it dries, I then epoxy the emitter to the heatsink using the same mixture....




1. As thermal transfer depends on area of contact I would suggest soldering the P7 to a large flat copper disk (or disk with a stud/base for P7) and NEXT attaching the disk to aluminum heatsink with an insulator between them.

2. The idea is to get rid of excessive heat, right? But if you use a bulky Al heatsink you will accumulate heat :thumbsdow IMHO finning the head would do the job.

-- M.


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## kongfuchicken (Apr 7, 2008)

1. An even better method would be to have the al sink anodized; a layer of anodizing has been shown to greatly decrease the thermal resistance at the junction as well as making the whole isolation of the positive slug a non-issue.

2. I thought that the point of a larger heatsink would be to increase the contact area to the body and facilitate the transfer from the slug to the outside of the light, as opposed to having a greater thermal mass... Fins on the body would help beyond that but I think having a larger heatsink would definitively help in the process of getting there.


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## Supernam (Apr 7, 2008)

Mel_PL said:


> 1. As thermal transfer depends on area of contact I would suggest soldering the P7 to a large flat copper disk (or disk with a stud/base for P7) and NEXT attaching the disk to aluminum heatsink with an insulator between them.
> 
> 2. The idea is to get rid of excessive heat, right? But if you use a bulky Al heatsink you will accumulate heat :thumbsdow IMHO finning the head would do the job.
> 
> -- M.



1. By doing this, the heat would have to travel from the emitter, through the solder, through the copper, through the "insulator", then would finally reach the actual heat sink. Why not just eliminate the solder and the copper disk? Look at the chart on post #14 above by PhotonFanatic. Solder is NOT a good conductor of heat. 

2. This is how I conceptualize heat and heatsinks. Imagine a a kitchen sink with the faucet running. The water is the heat, the sink is the... well.. sink. The surface area determines how fast the heat is dissipated and is analogous to the size of the drain in the kitchen sink. How big the kitchen sink is is analogous to the mass of the heatsink. If the sink floods, you have over heated. 

Anyway, a large o-sink may not dissipate heat any faster than a small one, because the exterior surface area will not increase as a result of using it. However, it's ability to hold heat and literally act as a sink allows the heat from the slug to GO SOMEWHERE. If the sink was small, the heat would go to the mag, but it would have to wait to be dissipated into the air which happens at a rate that is determined by its surface. In the mean time, the heat at the slug would be immense. The large heatsink would act like a reservoir holding the heat until the mag's dissipation catches up to the built up heat. 

Imagine this- A giant cube of copper with a mass of 10Kg and a smaller cube of copper with a mass of 1Kg. You insulate both cubes with some kind of super insulator that doesn't allow it to dissipate heat (eliminating surface area as a factor). You then attach a SSC P7 to each of the cubes. Which emitter will overheat first?




kongfuchicken said:


> 1. An even better method would be to have the al sink anodized; a layer of anodizing has been shown to greatly decrease the thermal resistance at the junction as well as making the whole isolation of the positive slug a non-issue.
> 
> 2. I thought that the point of a larger heatsink would be to increase the contact area to the body and facilitate the transfer from the slug to the outside of the light, as opposed to having a greater thermal mass... Fins on the body would help beyond that but I think having a larger heatsink would definitively help in the process of getting there.



1. I thought anodizing is a poor thermal conductor as found above in posts 11-14?


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## 2xTrinity (Apr 7, 2008)

Mel_PL said:


> 1. As thermal transfer depends on area of contact I would suggest soldering the P7 to a large flat copper disk (or disk with a stud/base for P7) and NEXT attaching the disk to aluminum heatsink with an insulator between them.


This is a good idea -- placing the (electrical) insulating layer ON the slug itself is the worst possible place to introduce extra thermal resistance, since there is very little cross-sectional area there for the heat to conduct. You're better off adding that insulator layer across an interface with larger surface area. However, that might be offset by the fact that you have introduced an extra interface (the slug/copper, then the copper/heatsink boundary). Determining which option would be better in reality is not simple to answer.



> 2. The idea is to get rid of excessive heat, right? But if you use a bulky Al heatsink you will accumulate heat :thumbsdow IMHO finning the head would do the job.


The idea is to prevent the _temperature_ of the die from increasing excessively. One way of doing that is to have a heatsink with a larger heat capacity (the amount of heat energy it takes to raise the temperature by a degree)

All else equal, the emitter on the more massive heatsink will run at a lower temperature. This will be particularly true for shorter runs.



> 1. I thought anodizing is a poor thermal conductor as found above in posts 11-14?


He was talking about resistance across an interface. It's possible that a smooth anodizing layer might allow a "tighter fit" than a simple metal on metal contact, even though the material itself is less conductive.

IMO I think it would be an interesting idea for someone to make a custom host out of copper pipe -- which is dirt cheap compared to the price of the copper bar stock being discussed  I also remember reading one poster on here a while back who was building a multi-emitter light into a D mag using Emoli cells. He was planning on thermal-gluing a copper pipe to the inside of the battery compartment to act as a spacer for the thinner emoli cells, and a supplement to the heatsink. For P7 builds, particularly multi p7 builds, that might be a good idea.


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## Mel_PL (Apr 7, 2008)

2xTrinity said:


> IMO I think it would be an interesting idea for someone to make a custom host out of copper pipe...



A pipe? Why not...
A short piece of thick-wall Cu pipe inside Mag body (between the top and swich) would give a large contact area to the body (over 40 sq. cm, will transfer heat fast from the slug, and would not accumulate as much heat as a solid piece of metal.


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## gojira54 (Apr 7, 2008)

As other people have already said a combination of copper and aluminium would be a great idea!
How about a 'donut' of Al as the main slug with a suitable diameter solid copper core in the middle extending up as the pedestal? Just two pieces pushed together with minimal machining required


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## Supernam (Apr 7, 2008)

I thought of the same thing! A copper pedestal/core would draw the heat straight down quickly and allow the heat to radiate outwards. A tight press fit would ensure efficient thermal conductivity. As you mentioned, machining might even be easier.


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## gojira54 (Apr 7, 2008)

I had a CPU heatsink which was made like that, I 'upgraded' to an all copper one but the al/cu combination seemed to work better!
A simple design would reduce machining costs but a solid copper core means more $$$ :s


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## darkzero (Apr 7, 2008)

CM said:


> Ceramic is a good thermal conductor. Aluminum oxide is a ceramic material. I think the epoxy mixed with Aluminum oxide is a good way to isolate the slug.


 
Thats assuring, thank you. The ceramic waffers I have are almost thick enough to use as spacer for the P4. The waffers I have measure 25mm x 25mm x .63mm. How can I cut them? Can I score it a snap the piece off like cutting glass? I'm not sure how to cut round tabs out of them other than using a dremel to shape them to size.




PhotonFanatic said:


> I fail to see why you wouldn't just use Arctic Silver Thermal Adhesive. A tube goes a long way, it's already mixed for you, it uses silver, and it works.
> 
> And it only costs $14.25. :devil:


 
Good salesman tactics, sound so good I'm almost sent Paypal for some. :wave:

I have both Artic Silver & Artic Alumina epoxy. I like to use the least amount as possible when epoxying emitters so the tubes last me a long time. I find if I don't use them for a long period of time, the tube of hardner starts to get thick & eventually not very usable. Maybe heating it up will soften it back up?

I used to pot converters with Artic epoxy & it got very expensive which is why I switched to using alumina oxide powder. I have so much powder that I'm set for a very long time.


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## CM (Apr 7, 2008)

Photonfanatic is not really just using a sales tactic, there is merit to his advice :devil: . Bottom line folks is that the less interfacing you do between dissimilar material, the better off you are for heat transfer. Remember that each interface adds to the total thermal resistance, and there is no such thing as a negative resistance. The key to the epoxy is use the thinnest layer as practical to prevent electrical contact to the slug. Once you isolate the slug, you can take anodizing off the [email protected] to make metal to metal contact. This only works if the O-sink is designed for removal of the anodizing--it will have to be oversized. This necessitates fitting of the O-sink to the [email protected] Kind of sucks but this is probably the optimum way to get the heat off the die.


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## Supernam (Apr 7, 2008)

I know this is a little off topic from the O-sink discussion, but it might be worth noting that the weakest link in a Mag set up as far as heat dissipation is between the head and the body. These parts are anodized and threaded together, and not very tight I might add. If you are lucky enough to find your desired focal point with the head cinched all the way down, then consider yourself lucky. I have never been able to do that. I always find that the head can wobble slightly on the body. This could not be good for thermal conductivity. I suggest using the High Density Arctic Silver thermal compound (available from PhotonFanatic, oops was that a sales pitch again? lol). I'll be using Arctic Silver Epoxy to "glue" the threads and also lock the head with a pin between the threads.


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## [email protected] (Apr 8, 2008)

Supernam said:


> I'll be mounting my AMC7135's right above the switch by AA'ing them to the body (with the chips touching the body). I think that the heat from the emitter will mostly conduct outwards through the head so the temperature of the body just above the switch will be cooler than the sink.



I vaguely remember someone around here made semi concave aluminium driver sinks intended to be adhered to the Mag bodies inner wall 'Shark sinks' or similar IIRC 



Supernam said:


> the weakest link in a Mag set up as far as heat dissipation is between the head and the body. These parts are anodized and threaded together, and not very tight I might add. If you are lucky enough to find your desired focal point with the head cinched all the way down, then consider yourself lucky.



I've been considering that very factor for my upcoming regulated P7 3D Mag mod, I was thinking if the LED heatsink were 'alternatively secured' to the inner wall of the Mag-host (or switch assembly) instead of nestling at the top of the threads it would be possible to find (and set) the optimal focal point with the head screwed on tight... then you'd still have the option to focus out to a floody beam (because it's not AA'd together :thumbsup:

As for a P7 dedicated O-sink... I'd be up for at least one I reckon (as long as it doesn't cost me a kidney) :twothumbs


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## jasonck08 (Apr 8, 2008)

Here is my take on this. Custom machining a heatsink is too costly! At a local electronics store, I could buy an aluminum heatsink for about $2-3, one larger than needed. It could then be trimmed down to size. Most heatsinks come in a rectangular shape. But it would obviously need to be round to be most effective. 

So people should be looking into online heatsink sources, as well as how they would modify the heatsink to make it fit…
 
Even old CPU heatsinks or North Bridge heatsinks might be an option.


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## CM (Apr 8, 2008)

jasonck08 said:


> Here is my take on this. Custom machining a heatsink is too costly! At a local electronics store, I could buy an aluminum heatsink for about $2-3, one larger than needed. It could then be trimmed down to size. Most heatsinks come in a rectangular shape. But it would obviously need to be round to be most effective.
> 
> So people should be looking into online heatsink sources, as well as how they would modify the heatsink to make it fit…
> 
> Even old CPU heatsinks or North Bridge heatsinks might be an option.



Costly? That's why we do these "interests" thread so as to amortize the cost among those interested. You do realize people spend thousands of dollars on lights on this forum? O-sinks like these cost about $7-$10 in quantities that would be consumed easily on the forum. Yes, CPU heatsinks cost $2 to $3 but not everyone has the means to modify them. You need precise fit in this case. You are not going to get it using a Dremel tool.


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## Supernam (Apr 8, 2008)

jasonck08 said:


> Here is my take on this. Custom machining a heatsink is too costly! At a local electronics store, I could buy an aluminum heatsink for about $2-3, one larger than needed. It could then be trimmed down to size. Most heatsinks come in a rectangular shape. But it would obviously need to be round to be most effective.
> 
> So people should be looking into online heatsink sources, as well as how they would modify the heatsink to make it fit…
> 
> Even old CPU heatsinks or North Bridge heatsinks might be an option.



This does not contribute to this discussion. (Let us know when you can make a better heatsink than the O-Sink for less than $10.)


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## yaesumofo (Apr 8, 2008)

I can easily have the parts anodized in order to isolate the emitter.
Copper plating the part is an interesting idea which I can do as well. I have a feeling that that would be of limited use and would just end up being an added cost.

Creating dual metal O-sinks sya a sink with a copper core like cpu sinks would be very expensive and is not a project I have the desire to follow up on. I don't see that many of you guys paying $50.00 for a mag light heat sink.
Yaesumofo




darkzero said:


> I took a Hotlips-C, milled the pedastal off, & threw a P7 on there. Ran it DD on 3 NiMh. On fresh cells it pulls 3A then drops off to 2.8A quickly. Running it for a few minutes starts to get the MagC pretty warm. Using thermal grease between the Hotlips & the Mag body also helped a great deal in dissapating heat. Having a beefier heatsink is defintely a great idea & I'm in for some too.
> 
> I isolate SSC slugs with a very thin layer of epoxy mixed with a good amount of alumina oxide powder, as thin as I can get it. After it dries, I then epoxy the emitter to the heatsink using the same mixture. With P4s I'm not concerned but with the heat of P7s I'm not sure how good the layer of thermal epoxy transfers heat. Well the body of the Mag gets pretty warm so I know it's ok somewhat.
> 
> I have these ceramic waffers that measure .025" thick. It's the same material the cree xre bases are made out of but just a tad bit thinner. Can I use these as isolators? I know ceramic withstands heat pretty well but is ceramic a good conductor for heat? Isn't alumina oxide some type of ceramic powder? I tried googling but couldn't find a definte answer.


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## yaesumofo (Apr 8, 2008)

Actually this is incorrect. the weakest link is the link between the mag body and the AIR. heat transfer between an O-Sink which has been AA epoxy into place will transfer heat quite well the hold up is when the heat is trying to move from the Mag body and the air. Fins would help. Anything which would add surface area would help. maybe the P7 is worthy of a nonpassive system...Maybe we need to add a Peltier device to the system... In order to work properly they also require good sinking or a little fan....

Crazy I know but knowing the extremely smart flashlight freaks out here nothing would surprise me in the slightest.
Yaesumofo



Superman said:


> I know this is a little off topic from the O-sink discussion, but it might be worth noting that the weakest link in a Mag set up as far as heat dissipation is between the head and the body. These parts are anodized and threaded together, and not very tight I might add. If you are lucky enough to find your desired focal point with the head cinched all the way down, then consider yourself lucky. I have never been able to do that. I always find that the head can wobble slightly on the body. This could not be good for thermal conductivity. I suggest using the High Density Arctic Silver thermal compound (available from PhotonFanatic, oops was that a sales pitch again? lol). I'll be using Arctic Silver Epoxy to "glue" the threads and also lock the head with a pin between the threads.


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## yaesumofo (Apr 8, 2008)

IN the end they are not too terribly expensive. )-sinks were sold for well under $15.00 (IIRC) (I can't find the thread but I think they were even cheaper maybe even $10.00 )for a part which (at the time) was designed to perfectly center the LUX III emitter. The 0-sink made it easy for many people to make modded Mag lights. 100's were sold and I am sure a vast majority were used as intended.

IN any event the O-sink is Not too expensive. They (were) a high quality precision part designed to do a specific job.
The Mass of aluminum does a great job of sinking the LUX III emitter.
IF I were to make a unit designed for the P7 I would make enough of them so they would be a reasonable price to the end user.
While I don't want to loose money on this project, The )-sink project was never designed to be a Hugh profit machine. It was designed to help as many end users ease into the world of Mag light Modding as possible.
with an O-sink some wire and an emitter anybody could mod a maglite and do it for around $20.00 -30.00 including the host.
My intention was never to make a big profit only to create a self sustaining project..which it was for some time. It is clear that it may be time again..though there are other heat sink makers around which may be pursuing the same goals...
Again my motive here is to help as many people modify a MAG with the latest and greatest and possibly most incredible emitter made to date. The P7. It is clear to me that the P7 lends itself to mounting in large lights rather than small single cell hand burners. The P7 is a BIG emitter makes a lot of light and heat. That heat needs to be moved. The O-sink may be the best way to achieve this. That is not to say that there may be other and better ways of achieving the goal we have set...We may see...
Yaesumofo




jasonck08 said:


> Here is my take on this. Custom machining a heatsink is too costly! At a local electronics store, I could buy an aluminum heatsink for about $2-3, one larger than needed. It could then be trimmed down to size. Most heatsinks come in a rectangular shape. But it would obviously need to be round to be most effective.
> 
> So people should be looking into online heatsink sources, as well as how they would modify the heatsink to make it fit…
> 
> Even old CPU heatsinks or North Bridge heatsinks might be an option.


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## ledaholic (Apr 9, 2008)

I'm in for one or more! And thanks for the effort.


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