Are You On Pot????? (potting and heatsinking with epoxy and silicon carbide)

Flashlight Modding and DIY Parts
1

Not that kind! Potting.

Do you pot your drivers?

As I have been pushing my drivers more and more and expecting more out of them I have been potting pretty much all of them. On some of these lights I'm sure it's overkill but I just like the idea of keeping my drivers safe. I really wish I had started doing this a long time ago. I am not exaggerating when I say that not potting has cost me a ton of money. I have at least a couple hundred dollars in destroyed drivers. Many of them from simply pushing them way too hard. I am convinced that some of my early disasters could have been avoided if only I had started doing this sooner.

Please chime in with your potting compounds and advice.

For me I have been using a combination of JB Weld and Silicon Carbide. I use equal parts of the JB Weld just like normal and mix in the fine grit silicon carbide until I reach the consistency that I'm looking for. The more silicon carbide I mix in the more like putty it becomes. Thicker stuff is good for molding around smaller drivers. Use less and it's good for running in and filling up areas on lights. I also use this on lights as well for adding heatsinking.

These are links to the silicon carbide and the JB Weld that I buy.

http://www.ebay.com/itm/141375753041?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Here are some picture of the mixing process and what it looks like before and after.

It starts out a lot like making dough for bread. It really doesn't seem like it's going to mix together at all. It's all clumpy and stuff. But you just keep at it kind of mashing it up and stuff and before long it all mixed together. Keep adding more until you get it the thickness you are looking for.

One of the big things is keeping air out. I will actually roll it up a bit to make sure that the air is squished out of it before applying and after I squish it down even more to do the same.

This is a SRK driver. Yes I'm potting the driver. I also epoxy extra heatsinking material to the back of the "pill" sometimes washers or copper whatever I have that I can fit that will be as solid and conductive as possible. The entire area under the pill will be filled with copper and potting compound on this light when I'm done.

This is a 4x so those are 8 wires coming up off of a JB driver. They come up through the center of the pill. As I'm filling everything in, I slide the wires down with it. So when it's done I have the entire head completely filled with copper and potting compound. I then clip the wires, strip them and wire it up. Noctigons and XM-L2's two with domes and one without is what this light got.

How do I know it works? Well the light gets hot very fast, the heat transfer to the outside of the light is almost instant. Also the lumens stay high instead of dropping off like they would without all the extra heatsinking and potting. I have over driven drivers and killed them without potting and then done the same mods to the same driver and potted they run just fine. This makes them corrosion free, impact resistant and it's much less likely that you will burn out a driver.

So are you on Pot??

2

I do not pot my drivers, but my mods are almost always small lights with either lineair drivers that have 7135's close to the edge, or recently 105C-based FET-drivers that produce hardly any heat al all. I did extra heatsink a lineair driver once using copper rings soldered over the outer ring that drove an infrared Oslon led, because the ledvoltage was under 2V and the 7135's had to burn 700mW each.

Do you use silicium carbide because it has particularly high thermal transfer properties, or is it just a filler to get the right consistency?

3

I bought it in the first place just for the thermal transfer but because you can turn it into a putty it makes working with it really easy. One thing I didnā€™t state that I should have is that as long as you use glass and clean up right away you can re-use the same bowl over and over. I messed up one night and forgot, so now I need to make another trip to the second had store to pick up another glass bowl.

I wonder how much different this is than Arctic Silver 5? I know that arctic silver also has silicon carbide. I looked up all the numbers on the different ceramics and silicon carbide was a lot better for heat transfer than alumina that they use in arctic alumina and others. Also the hotter it gets the faster it transfers heat and over time it will transfer heat even more. I guess it doesnā€™t even max out until itā€™s been used for 200 hours.

4

That sounds like you found the perfect stuff for potting, except for the dull colour: does JB-Weld come in fashionable colours as well? :-D

(I live in that part of the world that struggles to cope with the unavailabilty of JB Weld)

5

No JB Weld? How on earth do you ever fix cars, motorcycles and snowmobiles? :wink:

On the colors that's a good idea you could make a million bucks. Kinda like duct tape used to only come in grey. Between duct tape, JB weld and a hammer you can fix anything.

6

I'm a mad potter too 18650. Even if it just pulls out a few degree, they're the most important ones to get out. Just my opinion which may not be based on fact.

7

Iā€™ve yet to start potting, considered it but I just mess with the FW to much. One thing Iā€™m thinking about is finding a tiny 5 pin M/F connector and start adding those to my lights I need to reflash a lot, then I could pot them but still be able to flash, just leave the head of the connector sticking out of the pot.

8

Iā€™ve seen someone pot a driver entirely with Fujik. Would it even benefit from that stuff?

I like the idea of filling in gaps to maximise heat efficiency, although it means that you are no longer able to replace or make adjustments to the potted driver.

9

anything conducts heat better than air, so Fujik will help. But while you're at it it doesn't harm to use something better and this recipe sounds good.

10

Nah. But IĀ“ve used it before but based on ordinary silicone from the hardware store and mixed in lots of the silicon carbide dust you also use.

Gives you a few hours to work with it. And it mixes quite well. I put a few drops of silicone oil in it to make the mixing better. Also seemed to keep the air out of it better.

This compound can be remowed btw. If you know you might remove it later you can spray the driver and cavity in a thin film of silicone oil before applying it. Then it is quite easy to get out.

11

try ā€œdepleted fujikā€. spread it thinly on paper and let the paper absorb the silicone oil. scrape it off then spread again on another sheet. the consistency of putty

well thereā€™s still convection and radiation of heat. so styrofoam is worse than air

12

13

Ledsmoke wrote:

Nah. But IĀ“ve used it before but based on ordinary silicone from the hardware store and mixed in lots of the silicon carbide dust you also use.

Gives you a few hours to work with it. And it mixes quite well. I put a few drops of silicone oil in it to make the mixing better. Also seemed to keep the air out of it better.

This compound can be remowed btw. If you know you might remove it later you can spray the driver and cavity in a thin film of silicone oil before applying it. Then it is quite easy to get out.

Great tip. I will be trying this. I've just been using my potting recipe that I have a thread on. It's great because there is not curing time, but it's a hassle to remove.
14

Thanks for sharing.

Do you, or anyone know of a good place to buy suitable silicon carbide with free shipping?

15

Here in the USA it's almost always available domestically on ebay. Hopefully, you will have the same there in Norway.

16

I compacted a pure copper scrubber in my 15 led light. It does seem to help.

17

18

What grit of silicon carbide powder do you guys use?

19

I use one that is a mix of like 220 and 4xx. I have some 1500, but I don't use it because it goes airborne easily and I don't want to inhale it.

20

I noticed reading up on Arctic silver 5 that they actually use different grits in their mix. Iā€™ll be ordering more silicon carbide soon in various grits. Makes sense to mix the smaller particles with some larger depending on what you are using it for.