Need To Weatherproof An LED Mount - But How?

Discussion in 'The Garage' started by Digger1, Nov 15, 2012.

  1. Digger1

    Digger1 Adventurer

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    Hello all,

    I'm in desperate need of good advice here and I'm hopin' that one or more of you can help me out.

    I'm making a display for use on a motorcycle that involves some LEDs. The build info on this project bike is here. You need to register to get into this site, but no worries, Glenn (the Admin) will not spam you.....

    The LEDs in question are mounted on a section of PVC pipe that has been filed flat so that the LED mounting collars will sit flush with the exterior surface of said pipe. Here is a closeup of one:


    [​IMG]


    I need ideas on how to make this LED mount waterproof.

    My original idea was to smear some RTV inside the section of pipe, over the bottom part of the LED, but that will not work because there is not enough room for me to get inside the pipe and smear said RTV around. I tried smearing some of the same RTV around the outside of the mount, hoping to waterproof it in this way, but the RTV did not adhere well to the subject surfaces.

    Please keep in mind that the mounting collar must be sealed to the PVC pipe and that the LED lens needs to be sealed to the inside diameter of the mounting collar.

    These are my requirements:

    1. The sealing method must be waterproof, weatherproof, UV resistant, and very durable (lasting 10 years or more under savage conditions).

    2. The sealing method must not damage the LED lens in any way.

    3. The sealing method must be strong enough to keep the LED and its mount from moving around (note that the hole I drilled in the pipe was the smallest I could get away with - the fit is fairly snug already).

    4. The sealing method must not obscure the LED from being viewed.


    I'm thinkin' that some type of glue will work, but which one? I had a notion to try super glue, but I don't think that that stuff holds up well to moisture over the long term - I could be wrong, though.

    FWIW, I found these:

    http://www.digikey.com/product-detail/en/A-LED8-1RBAS-MR7-1-R/AE10577-ND/2295434?cur=USD

    However, they are much too spendy for me!

    FYI, here is the package that the LED and its mounting collar came in:

    [​IMG]

    I'm lookin' forward to your expertise, wisdom, and experiences!

    TIA!
    #1
  2. 9Dave

    9Dave Bazinga!

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    How about partially filling the pipe with clear epoxy?
    #2
  3. sailah

    sailah Lampin' it

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    I'm not clear on how it sits in the pipe. Lets see a pic of one dry assembled then we'll offer you our supreme advice
    #3
  4. Digger1

    Digger1 Adventurer

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    Hi Dave,

    Thanks for your input!

    The interior of the pipe has circuitry that I may need to access, so I want to keep things clear in there.
    #4
  5. Digger1

    Digger1 Adventurer

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    Good comment....here ya go:


    [​IMG]


    The circuitry and the LEDs are slid into the pipe from one of the ends. The LEDs poke through the two drilled holes.
    #5
  6. Digger1

    Digger1 Adventurer

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    What does everyone think of using Liquid Tape or Plasti-Dip for this job?
    #6
  7. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

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    Both liquid electric tape and plasti dip do not hold up reliably.

    As suggested, I would suggest a clear epoxy of some sort. My suggestion would be to call Fiberglass Coatings-
    http://www.fgci.com/ and talk to them and have them suggest a product to you. I have no affiliation with them other than as a very satisfied customer.

    Additionally, if you are manufacturing a product I would find a rubber or plastic cable grommet to push into the hole, it will look much much more professional and cost pennies when you buy a bunch of them.

    Here's a web search hit:

    http://www.directindustry.com/prod/heyco/rubber-cable-grommets-11746-372384.html

    [​IMG]

    And again, I'd say to call them and talk to a salesperson and have them suggest some options for you.
    #7
  8. Digger1

    Digger1 Adventurer

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    Grease,

    Thanks for the input on the Liquid Tape......

    Also, thanks for the links. I was considering a grommet for the assy.....

    Will post a link to my writeup when I finish this thing.
    #8
  9. FlySniper

    FlySniper Bleh...

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    Why not use clear pipe?

    Or one of those small, watertight, clear plastic cases they sell in the sporting goods section of your local big box store?

    Or a small hobby electronics enclosure.

    Or.....?
    #9
  10. LoneStrom

    LoneStrom Been here awhile

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    I'd also agree on the epoxy. You can use epoxies intended for electronics potting.

    They will flow very well after you mix it up, so you can make just enough for what you'll need. Then draw it up in a syringe and place it just behind the LED. Bake it for a few hours, or just let sit for a couple of days.
    #10
  11. troidus

    troidus Long timer

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    I'd be worried about the gray pipe failing. I don't think that stuff is weather resistant, but I could be wrong.

    I'd consider epoxying a red lens over the outside of both cutouts (or maybe one lens each), but leave a weep hole from the inside of the lens diameter to the interior of the pipe so moisture can escape. I'm assuming that all of the LEDs are red in this application--if not, substitute a lens color that matches the LED color.
    #11
  12. Digger1

    Digger1 Adventurer

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    I was wanting something like that during the planning stages of this project, but didn't know what exactly to look for.

    Plus, it's for a KLR......so it's gotta be at least a little ugly.......:D
    #12
  13. Digger1

    Digger1 Adventurer

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    Yep, I agree, epoxy's a good choice. I'll consider same if my primary plan doesn't work out (see below).

    I won't be able to get anything behind the LEDs though, as things are kind of tight inside the pipe section I'm using for a housing.
    #13
  14. Digger1

    Digger1 Adventurer

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    troid,

    The gray pipe is schedule 40 electrical conduit, 3/4" ID. It is UV resistant and rated for outdoor use, which was one of the reasons I chose it for a housing.

    There will be a place for moisture to escape from the housing.
    #14
  15. Digger1

    Digger1 Adventurer

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    Hey everyone, how's this for an idea:

    Use Marine Goop as the sealant/adhesive.

    I like this solution since I've already got some Marine Goop in the garage and have had good luck with it in the past. The only drawback is that it's kind of thick. However, I can thin it with some toluene (also in the garage). Then, I won't have to add to the pile of glues and other chemicals that I already have on hand and hardly ever use....

    For everyone's information, I'll be posting a link to my writeup about this project as soon as said project is complete and the writeup is done.
    #15
  16. Bob_M

    Bob_M Been here awhile

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    Careful with that Toluene. Its real nasty stuff, don't try to huff it out of a paper bag just to see what happens.

    Can you just completely fill the pipe with epoxy? I'm thinking this would encapsulate the wiring and coat the back of the LEDs too. You can thin epoxy with isopropol alcohol rather then Toluene.

    You should find something on McMaster Carr's web site, evenjust for some guidance they have everything. If it isn't on their web site, try Googling Loctite or Henkle or 3M for potting material compatible with PVC and water proof. I think you will find something that will work. This is not a difficult potting application. Does it have to withstand high pressure of thermal cycling?
    #16
  17. Digger1

    Digger1 Adventurer

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    #17
  18. Beezer

    Beezer Long timer

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    why not use the pvc cement made for the pipe? I have a friend that uses it to seal the floats on his seaplane & swears by it for that... he's been using it for years & it seems to work (I have other opinions as far as airplanes are concerned).
    #18