How to pot? Looking for knowledge resources about potting

Lux-Perpetua · 2018-12-06T14:26:21.000Z

Hi there,

I'm looking for more information about potting (how to do, what for, etc.). Any information would be greatly appreciated.

https://www.pflexpro.com/Potted-Flashlight-and-P60-Drop-In-s/1841.htm

Cheers,

Thomas

slowtechstef · 2018-12-06T18:11:41.000Z

There is some information in this thread:

Potted flashlight LED Flashlights – General Info

All this talk about potted flashlight like Fenix E01 made me wonder so I took a picture of one of my other AAA flashlights (Inova XS). I hope the picture is clear enough to see, that black substance is that epoxy? [image]

PFlexPro uses Stycast 2850FT.

Enderman · 2018-12-06T18:24:34.000Z

Potting compound for building a tank light Flashlight Modding and DIY Parts

I’m building a Convoy M1 with Luxeon MZ and a FET driver and I’m thinking of potting it as well to make it a tank light. I’ve also been reading a lot on BLF about potting compounds but a lot of the posts are a couple years back. My question is what potting compound would be good for this? My main reason of potting is just for durability, not so much for heatsinking, although that would be a plus. I know most would mix some epoxy with silicon carbide powder but I would prefer it without since I’m…

Agro · 2018-12-07T07:48:05.000Z

Potting Drivers - Budget reversable option? Flashlight Modding and DIY Parts

[image] Update: So here are the 2 recipes that have been developed. They have not been tested for safety or effectiveness. They are very cheap way to reversibly pot your driver or what ever: Very easy, low cost, no wait recipe: Ground Silicon Carbide (Both Medium and Fine Grit) - Suggested by TexasPyro Duct Seal - Suggested by Leaftye Complete removal after being in a light for an extended period is not an easy task. Pull off what you can by hand and then us an alcohol to clean off t…

Lux-Perpetua · 2018-12-07T07:50:13.000Z

Thank you guys!

Tom_Tom · 2018-12-07T19:59:47.000Z

Also study this:

assemblymag.com

Dispensing Potting Materials

There’s more to the potting process than simply pouring a liquid resin onto an assembly.

And maybe think about rigging up a vacuum chamber (an old fridge compressor and a re-purposed pressure cooker might do the job)

Used to doing this on a bigger scale, vacuum bagging of epoxy layups for nautical and motorsport applications.

But, fundamentally choose a properly designed material system that you can source, experiment, and practice with, until you understand it.

Don’t expect to get it right first time. Dolloping or injecting things, one-off, with a glob of random gloop is easy. Doing it properly, for engineering reasons, then evaluating the result scientifically, rather than because “it seemed like a good idea” is quite different.

I say again, it’s not generally done for thermal reasons. It’s an environmental protection, ruggedness, none-maintainability, built in obsolescence, solution, which is perfect for those markets. And also costs quite a lot to do properly with decent materials, and hard-learned experience.

If you make e.g. P60 drop-ins for real tactical (or wannabee) use, on e.g .308 upwards, then yes, it certainly has a use. And you’ll never know whether you got it right until, say ten years of field feedback, or maybe 168 hours in the environmental simulation chambers.

Otherwise good construction, use of none-pc solders, pristine cleaning (just a bristle brush and 50:50 IPA/Di water), and suitable conformal coating, with maybe some re-enforcement of weak points e.g. USB connectors (ugh), should be enough.

slowtechstef · 2018-12-11T16:38:38.000Z

Tom Tom:

Also study this: Dispensing Potting Materials | ASSEMBLY

Interesting article, thanks for sharing!

Tom Tom:

And maybe think about rigging up a vacuum chamber (an old fridge compressor and a re-purposed pressure cooker might do the job) Used to doing this on a bigger scale, vacuum bagging of epoxy layups for nautical and motorsport applications. But, fundamentally choose a properly designed material system that you can source, experiment, and practice with, until you understand it. Don’t expect to get it right first time. Dolloping or injecting things, one-off, with a glob of random gloop is easy. Doing it properly, for engineering reasons, then evaluating the result scientifically, rather than because “it seemed like a good idea” is quite different.

NASA has "technical reports" on potting electronics for spacecraft purposes:

https://ntrs.nasa.gov/search.jsp?Ntx=mode%20matchallpartial|mode%20matchall&Ntk=All|Abstract&N=0&No=90&Ntt=potting|potting

Edit: somehow the URL is imcompatible with the BLF forum software; you can also go to https://ntrs.nasa.gov and search for "potting" in the abstract field. NASA also mentions the use of vacuum chambers.

Edit 2: edit link with advanced post editor

Enderman · 2018-12-07T23:09:18.000Z

slowtechstef:

NASA has “technical reports” on potting electronics for spacecraft purposes:
https://ntrs.nasa.gov/search.jsp?Ntx=mode%20matchallpartial\|mode%20matchall&Ntk=All\|Abstract&N=0&No=90&Ntt=potting\|potting

Edit: somehow the URL is imcompatible with the BLF forum software; you can also go to https://ntrs.nasa.gov and search for “potting” in the abstract field.

NASA also mentions the use of vacuum chambers.

You have to go into advanced post editor and insert the link using the proper tool.

Tom_Tom · 2018-12-08T00:30:09.000Z

Yes , I know some things about potting for space application, but that was a long long time ago.

Just not sure it has any relevance for here and now. Unless you are doing extreme stuff where it has a functional use. In which case, I’d be pleased to compare notes.

Agro · 2018-12-10T10:59:21.000Z

Is there a download button on the NASA site? I fail to find any…

Tom_Tom · 2018-12-11T00:27:46.000Z

If you are truly interested, then you will discover how to access NASA resources.

Which, by bye the way, are not always perfect, there is some defensiveness about private sector, and foreign organisations, career building and dissing of genuine knowledgeable people, and other Space Agencies do exist, and shoot up rockets, some of them even work. Mostly in private hands, or not. State owned. It’s allowed.

That said, they still somehow seem to keep the funds flowing in, and real useful Science coming out. Long may it continue.

If you really want to talk about Space, then that is a completely different subject, that moves things onto a completely different level. LEDs just don’t begin to matter, far more important things going on, or not. Honestly. Its all still happening, and accelerating.

Not sure why I am even bothering to post this, was it something to do with LEDs, or just Righteousness ?

Take a look at http://stuffin.space and see what is going on overhead.

That’s my background.

Maybe search for Olympus 1 (AKA L-Sat), perhaps the most unluckiest satellite ever. One of mine.

slowtechstef · 2018-12-11T11:16:24.000Z

Enderman:

You have to go into advanced post editor and insert the link using the proper tool.

Thanks for clearing that up. :+1:

slowtechstef · 2018-12-11T16:46:35.000Z

Agro:

Is there a download button on the NASA site? I fail to find any…

I fixed the download link in my post.

Here it is again: https://ntrs.nasa.gov/search.jsp?Ntx=mode%20matchallpartial|mode%20matchall&Ntk=All|Abstract&N=0&No=90&Ntt=potting|potting

Not sure if all of these reports are directly relevant to flashlights, however NASA is an example of an organisation:

with an active interest in potting as a solution for practical problems,
doing active systematic and scientific research on this topic,
and is also willing to share to knowledge via open access reports.

The combination of 1,2, and 3 is quite rare. NASA is also quite likely a lead user actively looking for potting solutions that are probably not commercially available (yet), which increases chances they might have developed some innovative solutions from which others, with similar problems in other domains, might learn.

Tom_Tom · 2018-12-12T00:08:58.000Z

Potting for space application is a very specialised topic.

During launch of a satellite, there is extreme vibration and acoustic noise, hence potting of some critical parts for mechanical reasons, though it is best avoided.

There may also be some thermal control benefit in the vacuum of space (no air, you see), but that’s generally managed much more precisely, and in completely different ways.

Then when in service, in microgravity, even zero gravity, and vacuum, out-gassing of chemicals is a great concern, any such vapour etc. hangs around like a miasma, and can condense onto optical components and degrade the performance of sensors, lenses, mirrors, imaging devices, by slowly fogging them up.

The extremes of temperature can be immense, between sunlight and shadow, depending on orbit or interplanetary trajectory. Ordinary materials are not designed or tested for this, and rapid degradation is the norm.

These things simply must not fail, until e.g their thruster propellant runs out, or their solar panels and batteries degrade too far, or their radio signals become too weak, or the antenna pointing mechanism, and associated gubbins, wears out. Fogging up the star sensors (also called star trackers, but that’s a misnomer, the stars are essentially fixed above us, it is we who revolve beneath) would be very bad (these things do still navigate by the stars, there is no other way). Even then there can be strategies to keep the science coming, Nasa is still superb at this.

voyager.jpl.nasa.gov

Voyager - Mission Overview

en.wikipedia.org

NASA Deep Space Network

The NASA Deep Space Network (DSN) is a worldwide network of American spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA's interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the Solar System and the universe, and supports selected Earth-orbiting missions. DSN is part of the NASA Jet Propulsion Laboratory (JPL). DSN currently consi...

These are powered by Plutonium-238 RTGs though, which also keep them warm and cosy. Half life 48 years ISTR, so lots still left, as long as the thermopiles are still in good shape.

en.wikipedia.org

Radioisotope thermoelectric generator

A radioisotope thermoelectric generator (RTG, RITEG), sometimes referred to as a radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity by the Seebeck effect. This type of generator has no moving parts. Because they don't need solar energy, RTGs are ideal for remote and harsh environments for extended periods of time, and because they have no moving parts, there...

However NASA, and other US agencies, are running out of the stuff, and Russia can’t/won’t supply any more, as they used to, along with their RD-180 rocket engines on which the Atlas-V rocket is utterly dependent. They are keeping their own for themselves. Those are some of the unintended consequences of applying sanctions to key people and companies. And not planning for the future.

Scientific American

New Supply Could Prevent Deep-Space Plutonium Shortage

Public-private partnerships may boost available nuclear fuel for space exploration

Typically a big NASA mission will last the length of a career, for the leaders. If you start young you might get two or three such opportunities, working your way up, before retiring.

Naturally some aspects of design and materials selection can be very conservative, trusted and certified materials will be selected by default, and it would take a bold engineer to argue at design review why choosing something different was worth the risk.

Meanwhile, back on Earth, some more discussion of the pros and cons of different chemical systems, and what potting is useful here. And no, thermal conductivity is not one:

https://www.electrolube.com/blog/2017/02/13/a-potted-guide-to-resins-and-why-we-use-them/

Recommendation: start your evaluation with a slightly flexible two-part polyurethane.

I’ve had good results with 3M™ Scotch-Weld™ Urethane Adhesive DP620NS

3M ID B40066434

It’s not advertised for potting, and the price will make you weep, but it is still what holds many, if not most, F1 cars’ electronics boxes, sensors and connectorised wiring harnesses together.

And other important things.

3M, Raychem, and Hellerman Deutsch are still the trusted suppliers for the basic materials and connectivity stuff. For the clever bits, that’s another matter.

slowtechstef · 2018-12-12T08:05:46.000Z

Tom Tom:

Take a look at http://stuffin.space and see what is going on overhead.

That’s my background.

Maybe search for Olympus 1 (AKA L-Sat), perhaps the most unluckiest satellite ever. One of mine.

Ah, a rocket scientist

During my PhD research one of my roommates was a space-scientist-turned-social-scientist. If I remember correctly he had worked for ESA for a while until his project got defunded. Great guy, brightest of the bunch, fantastic sense of humor, and walking B-movie film encyclopedia. Good times…

kiriba-ru · 2018-12-12T08:23:42.000Z

Sorry for little offtopic. What happens when you dont do potting when it is necessary (and a little of actual skill level of russian military engineers).

Lux-Perpetua · 2018-12-12T10:47:57.000Z

So they could not gather any data from the flight recorder due to too many damaged chips on the logic board, right?

kiriba-ru · 2018-12-12T11:07:05.000Z

I do not have any quality education or experience in developing boards or gadgets with high bump resistance level.
But people who do, wonder why internals are not filled with some resin.
I also wonder - why any modern automotive ecu have more protection and more suitable components than black box from supersonic aircraft.

P.S. 13 from 16 flash chips were physically broken by kinetic force, 2 were damaged and one had no visible damages and probably could have some information.

Tom_Tom · 2018-12-12T19:26:04.000Z

kiriba-ru:

Sorry for little offtopic. What happens when you dont do potting when it is necessary (and a little of actual skill level of russian military engineers).

https://www.youtube.com/watch?v=tlGsIt9fZs8

Hilariously bad

And they did this live, televised in front of a press gallery ?

It seems as if the main man had been on the vodka, and sourced his poor tools as cheaply as possible from the local DIY store.

Ill-fitting un-buttoned stained lab coats and gloves, only on display to try to create an air of professionalism for the cameras.

Perhaps somebody didn’t want the data recovered, and this was a convenient way to arrange it.

There is some excellence in Russian engineering, just not on display here. At NPO Energomash for example, the USA relies on their unsurpassed RD-180 rocket engines to power the Atlas-V, without which the military, and NASA, would have no launch vehicles. Unless they intend to use SpaceX, going forward, which would be bold.

kiriba-ru · 2018-12-12T19:48:04.000Z

Right, it was online tv programm.
In USSR (and still in some spheres nowadays) nobody counted resourses spend for project (development). For example, if you devide selfcost of one bridge by number of cars that will pass it within whole lifetime, you will get $1000/car.
If you count money, and you know how much hours this work can take, you will use any possibility to avoid it if somebody have already solved similar problems. Dozen engines can be much cheaper than developing own compatitive product.