How to pot? Looking for knowledge resources about potting

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Lux-Perpetua
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How to pot? Looking for knowledge resources about potting

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

Edited by: Lux-Perpetua on 12/06/2018 - 09:27
slowtechstef
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There is some information in this thread:
http://budgetlightforum.com/node/59780

PFlexPro uses Stycast 2850FT.

Enderman
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Agro
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Lux-Perpetua
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Thank you guys! SmileBeer
Tom Tom
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Also study this:

https://www.assemblymag.com/articles/88263-dispensing-potting-materials

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
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Tom Tom wrote:
Also study this: https://www.assemblymag.com/articles/88263-dispensing-potting-materials[... Interesting article, thanks for sharing!
Tom Tom wrote:
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
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slowtechstef wrote:

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
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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.

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

Tom Tom
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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
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Enderman wrote:

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

Thanks for clearing that up. Thumbs Up

slowtechstef
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Agro wrote:
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:

  1. with an active interest in potting as a solution for practical problems,
  2. doing active systematic and scientific research on this topic,
  3. 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
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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.

https://voyager.jpl.nasa.gov/mission/

https://en.wikipedia.org/wiki/NASA_Deep_Space_Network

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.

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

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.

https://www.scientificamerican.com/article/new-supply-could-prevent-deep...

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...

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
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Tom Tom wrote:

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 Smile

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…

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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).

Need a vlogger for machine accessories reviews

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

kiriba-ru
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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.

Need a vlogger for machine accessories reviews

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kiriba-ru wrote:
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).

Hilariously bad Shocked

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.

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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.

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