FS: Custom machined laser hosts

[paul1598419]

Copper wicks the heat away faster than aluminium, but alum. transfers to air better.

I have heard many people say this, but can't find a reason for it. Could you provide a citation, Chris? I still don't believe this is true. :thanks:

 

[Alaskan]

Can't reference it, but have read this from several different sources over the last 20 years, started with CPU's, maybe Toms hardware web site? I don't think is a marketing lie.

If it is, may simply be due to the density of copper for a physical sink, then aluminum for easy transfer to air. Why would alum. transfer better? Perhaps it doesn't but used because copper doesn't machine well and isn't cheap.

 

[paul1598419]

Yeah, everyone says the same thing, but it doesn't make sense to me. The thermal conductivity is what it is, and there aren't other quantifiable qualities of these materials to back that statement up.

 

[Alaskan]

I did find this on Toms hadware:

Aluminium is used because it stores a lot of energy without increasing in temperature much, so its easier to keep cool despite it being rather deficient in transferring the heat. Thats why copper is used for bases and heatpipes, and why heat pipes are used so much in high quality heatsinks, to overcome the deficiency in heat transfer in aluminium fins. The copper transfers the heat, and the aluminium stores the heat away from the CPU, thus keeping the CPU cool.

 

[ElectricPlasma]

I like copper better than brass for heat sinking, but I would be fine with brass battery holder and focus knob. I'm interested in what you have in mind with exotic alloys.

I was thinking of messing around with titanium and bronze, not anything crazy but certainly unique. I can't say I'd use them for a laser host anytime soon, maybe the bronze though. When I have extra time on my hands I'll come up with something.

Titanium is pretty fun to work with actually. It's got really neat oxidation properties too and can be "anodized" with a torch. The only downside is that it's pretty tough on the tools and is very expensive.

On the matter at hand with the thermal conductivity of both metals, I'm leaning towards what Alaskan is saying. I've noticed with a lot of the heatsinks on my hosts (especially with the larger mass ones) that when it comes to aluminum versus copper, the copper tends to heat up quickly, usually noticeably faster than the aluminum would take to heat up. Other than that I can't be too sure on which is "better", but both seem to do the job for sinking diodes.

 

[paul1598419]

From the three laws of thermodynamics, heat can be moved from one body to another without doing macroscopic work by conduction, convection and radiation. Heat will move from one body to the other when they are in thermal contact until an equilibrium is reached. Primarily what we are interested in is radiant heat. The rate at which a body emits radiant energy is proportional to the fourth power of its absolute temperature, also known as Stefan's Law. P=sAeT^4, where P=power radiated by a body in W= watts, s=a universal constant, 5.6696 X 10^-8 W/m^2, A=surface area of the body in m^2, e is a constant called emissivity and T= absolute temperature in degrees K. As can be seen by this equation, the radiant energy is independent of the material it is made of. So, it would seem that heat is moved into the air from a body simply by its surface area and not because of its ability to conduct heat into or out of it. If you have something more to add to this or to counter it, please show me.

 

[dden4012]

From the three laws of thermodynamics, heat can be moved from one body to another without doing macroscopic work by conduction, convection and radiation. Heat will move from one body to the other when they are in thermal contact until an equilibrium is reached. Primarily what we are interested in is radiant heat. The rate at which a body emits radiant energy is proportional to the fourth power of its absolute temperature, also known as Stefan's Law. P=sAeT^4, where P=power radiated by a body in W= watts, s=a universal constant, 5.6696 X 10^-8 W/m^2, A=surface area of the body in m^2, e is a constant called emissivity and T= absolute temperature in degrees K. As can be seen by this equation, the radiant energy is independent of the material it is made of. So, it would seem that heat is moved into the air from a body simply by its surface area and not because of its ability to conduct heat into or out of it. If you have something more to add to this or to counter it, please show me.

In over my head but interested. Sorry for the thread jack EP. This really deserves to be it's own thread.

 

[paul1598419]

It is fascinating how these composite materials used to make such things as the shuttle's tiles are able to dissipate heat so rapidly. They are actually of very low density which, in turn, makes them able to shed this heat so extraordinarily fast. It is a matter of not taking in much of the heat to begin with.

 

[paul1598419]

Bump, for EP.

 

[ElectricPlasma]

Thank you Paul, I'm hoping to have a couple hosts ready some time this week! Been working on a lot of private orders recently.

 

[paul1598419]

I'm glad it is all working out for you. I'll be looking forward to your new stuff for sale. :yh:

 

[CynicalBrad]

I thought the copper vs aluminum debate was ended with copper being far superior but more expensive. It has a higher thermal density AND wicks heat faster hence why you feel if warm up away from the heat source so much quicker. Think of it this way, our diodes are putting of just as much heat regardless of which is used, would you prefer to wick that heat away quickly or more slowly? Intel uses a copper slug I their cpu heatsinks to pull heat from the die faster and then transfers that to the surrounding induction cooled aluminum which is cheaper and can be extruded easily in complex shapes.

Also, would you be able to make something just like the brass hosts in your uppermost right picture on the OP but solid brass with perhaps a kneeled midsection vs that black material? If so, I may be interested in about a month.

 

[Lifetime17]

Hi,
Good point ,Alaskan said it all in a prior post. An all copper sink isn't bad . But add some AL yes very efficient . Thats why i favored making a AL & CU sinks. But you can't beat copper also and leave it in the back seat.

Rich

 

[ElectricPlasma]

Added a couple hosts for sale in the OP, been a little while since. Also, decided to play around, here's a pretty different heatsink style:

Also, would you be able to make something just like the brass hosts in your uppermost right picture on the OP but solid brass with perhaps a kneeled midsection vs that black material? If so, I may be interested in about a month.

Yes, I could do that, only the bigger one though (14500 battery bay) since I don't have any 10440 tail cap switches left. Do you mean knurled, as in the decorative pattern? If so, I could give it a try. The black material is a carbon fiber wrap BTW, it's hard to see since the image is small.


Edit: I forgot to mention, I'll be out of town from the 14th to the 21st, in case anyone's interested in getting a host

 

[ElectricPlasma]

2*18650 host sold!* One host left under "stock hosts"!

*You'll see this host again some time, I love both the design, and making it

 

[paul1598419]

I went to look at the other stock host you have and I couldn't find a price for it. Just the shipping costs to the USA. Is it the 501B remix? The one with the copper heat sink?