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ArcticMyst Security by Avery

Survival Laser S4X duty cycle

Benm

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Stainless isn't that well a thermal conductor, though it's by no means useless either.

Aluminium would probably be the material of choice in most cases though, as it's lighter, cheaper, easier to machine and also has better thermal conductivity. Also anodization can make it very durable.

Copper would also be good in terms of thermal conductivity, but is harder to machine and more expensive compared to aluminium, though it does make better electrical connections which could be a consideration if you use the host body to carry supply currents (which is done in most handheld/pointers).

Neither really is the big issue though: the biggest thermal resistance of a total system usually is that between housing and air. In many things we solve this problem by having forced air flow (like in your laptop or car) but this isn't all that feasible for portable lasers - though there are some designs that actually have it.

My point about duty cycles is that it's often idiotic: You get something like 2 minutes on, 1 minute off. This effectively means that your existing heatsink is already 2/3rds of the way there from being able to run the laser continuously.

So no, it doesn't have to be gigantic to allow continuous operation at all, it needs about 50% more surface area to work. Practically it could have to be a bit bigger than that 50% due to airflow constraints and such.

But the idea that you can have a laser the size of a pen that can operate 2 minutes on, 1 minute off would have to become something like the size of a 4D maglite is completely ridiculous.
 





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Stainless isn't that well a thermal conductor, though it's by no means useless either.

Aluminium would probably be the material of choice in most cases though, as it's lighter, cheaper, easier to machine and also has better thermal conductivity. Also anodization can make it very durable.

Copper would also be good in terms of thermal conductivity, but is harder to machine and more expensive compared to aluminium, though it does make better electrical connections which could be a consideration if you use the host body to carry supply currents (which is done in most handheld/pointers).

Neither really is the big issue though: the biggest thermal resistance of a total system usually is that between housing and air. In many things we solve this problem by having forced air flow (like in your laptop or car) but this isn't all that feasible for portable lasers - though there are some designs that actually have it.

My point about duty cycles is that it's often idiotic: You get something like 2 minutes on, 1 minute off. This effectively means that your existing heatsink is already 2/3rds of the way there from being able to run the laser continuously.

So no, it doesn't have to be gigantic to allow continuous operation at all, it needs about 50% more surface area to work. Practically it could have to be a bit bigger than that 50% due to airflow constraints and such.

But the idea that you can have a laser the size of a pen that can operate 2 minutes on, 1 minute off would have to become something like the size of a 4D maglite is completely ridiculous.

Nicely put Benm :)
 
Joined
May 15, 2016
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Basically it's a matter of looks (SS) vs duty cycle (S4X). With the S4X and the extended and tapered copper heatsink the duty cycle should be way more than 2 minutes on; as the recommended duty cycle for the Survival Laser 7 is 2 minutes on, 1 minute off with the freaking NUBM44.
 
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Hi,
In an S4X for a longer cycle I dont use the copper sink that fits it , its way to small for the larger diodes. I machine a sink to fit the diameter of the host or larger like this S4X with a N520 in it.. And the same goes for the S4 host

Rich:)
 

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Benm

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I'd be a bit careful with powder coating.

Anodizing is usually not much of a factor in thermal design - most of the heat is emitted in the far IR and it doesn't make a huge difference if you anodize some aluminium host in clear, black or some fancy color.

Power coating however adds quite bit of more material that isn't very thermally conductive, so it could make your product perform worse.

How big that effect is depends on a lot of factors, but it's something that can be measured quite easily, and probably should be: especially if your host design is good enough to support nearly continuous operation but just not there yet.

I've seen some chinese designs that claim a duty cycle like 50 seconds on, 10 seconds of... probably completely bogus specs, but if that were the case just make the damn thing 20% larger or reduce the output power by 20% so it works without interruption if you ask me. You can do a special 'overdriven' version that needs to cool down between runs for people that want the absolute maximum momentary power (or have no idea what they are talking about).
 
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hi, Sorry to say but the coating does not interfere with the heat dissipation . With AL and ribbing the heat still wicks away no problem have tested it with the NUBM44 many time and it still dissipates the heat quickly just as much as anodizing not much difference . And the colors can match the WL Solid powders are applied thin and are very durable and the translucent powders are even thinner so basically our run times of these diode are relatively short and won't matter or interfere with heat wicking . My heat sinks are matched closely in mass to the diodes used and I dont skimp on material ever. But I guess your entitled to your opinions thank you for your reply..

Rich:)
 
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Apparently the C6 is also available with an aluminum finish instead of black anodized. The duty cycle should be the same with the C6 and S4, since they weigh pretty much the same, right? If yes, I'll probably just get the C6. If I get the S4X, I'll use a 9mm diode instead. If I get that big of a host I might as well just use a more powerful diode.
 
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Apparently the C6 is also available with an aluminum finish instead of black anodized. The duty cycle should be the same with the C6 and S4, since they weigh pretty much the same, right? If yes, I'll probably just get the C6. If I get the S4X, I'll use a 9mm diode instead. If I get that big of a host I might as well just use a more powerful diode.

Hi,
I substitute the smaller Copper sink for a much larger sink, either in AL , CU or AL with a CU core pressed in. And the application depends upon the diode being used. Even the C6 and the S4 smaller hosts as well, Here is a S4 and a S4X with my sinks, the S4 in the pic has a custom Sanwu Be adapter that fits the extended sink.

Rich:)
 

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Encap

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Apparently the C6 is also available with an aluminum finish instead of black anodized. The duty cycle should be the same with the C6 and S4, since they weigh pretty much the same, right? If yes, I'll probably just get the C6. If I get the S4X, I'll use a 9mm diode instead. If I get that big of a host I might as well just use a more powerful diode.

If you don't mind the larger size the SX4 is the latest released design by SL--a better and more substantial host that can handle any diode.
If you are investing time and money all the other parts and the time to assemble it all don't rule out the SX4--it is a great host and not an excessive amount more.
 

Bacon

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Yep ↑ When I got my S4X it ended up being a lot bigger than I thought. Although not the same diode as yours; Im using an oclaro at 1.2A. When I get some time I might do a temperature test with a heat probe and some thermal camera shots. Im not very worried about it getting hot though :D
 
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The stainless steel host is very nice. Heavy and shiny. Mine holds my last NDG4216. And FYI the SL aluminum heatsinks are rather short the extended tapered copper heatsinks are the way to go with either of your choices. The SL focus tips are very nice but a little pricy @ $10 but I have a few.
 
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I noticed you've been wanting a 488nm direct diode laser for sometime, Dan. Have you taken advantage of any of the binned diodes that have come out recently? That 488nm laser is not only possible, but really affordable too.
 
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Hi BS,
SS is not a good heat conducive , Aluminum or copper is much better for these builds as most have stated here.

Rich:)
 
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copper heatsink is good but i think aluminium is better in this case
A copperheatsink is only good when they are covered by an outer layer of aluminum, as they keep the heat for quite some time
and a copperheatsink will make you feel uncomfortable because they are hot when run long - while aluminum is cooler and if you put driver at 1.25 A you can use 2 min no problems
-i think so

Great tip. All my lasers had solid copper heatsink, brass hosts. Now I would choose a heavy aluminum host. I fried a couple diodes already
Rep for you
 
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Sorry for the necropost, but I think I'll use a Sanwu G7 instead of a G2 lens. Will the extended lens spring work better with the 9mm lens holder or the 7mm one? And what would the divergence be with a PLTB450B? Hopefully equal to or less than 1mRad.
Also, I'll use their M9*0.5 adapter for the beam expander as a focusing ring, as it's a bit cheaper than a Survival Laser External Focusing Ring and I'm also considering buying the Sanwu beam expander a few months after building the laser.
 
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