A better pre-fab waterproof box

Discussion in 'Research and Development' started by Beaver, Nov 14, 2016.

  1. Beaver

    Beaver 2020 Rookie of the Year Admiral (Supporter)

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  2. thegeek

    thegeek Well-Known Member

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    The problem with "water retaining" boxes is that they don't seal well in general because of a non-compliant seal.
    The interface is problematic because it changes when under pressure. RTV and plexiglass make a good enough seal but when
    you push down on the cover it doesn't seal.
    I use Duct Seal mixed with Vaseline. Electric boxes on the exterior of buildings have issue with condensate and intrusion of water
    into the tubing that enters the building, Duct Seal (very similar to balistic putty) is the gooie clay like stuff that electrical contractors
    use to seal that tubing, available at Home Depot or Lowes (electrical department). Mix that with Vaseline and it becomes very viscous
    and sticky. I use it to seal between the box lid and the RTV gasket on the box.
     
  3. SteveT44

    SteveT44 Well-Known Member

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    Ground that puppy to the water and you'll have some good nuclear EMP protection!
     
  4. Beaver

    Beaver 2020 Rookie of the Year Admiral (Supporter)

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    Heh, that's why I don't use them.
     
  5. Beaver

    Beaver 2020 Rookie of the Year Admiral (Supporter)

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    Oh yeah, I have enough trouble keeping my boat working reliably as it is, now I have to refit it to withstand and EMP. :confused::confused::confused:
     
  6. jadfer

    jadfer Well-Known Member

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    I have been using similar plastic project boxes with very good success lately. I test by dunking in water after assembly to be sure that the 'seal' is good however all my components are water-proofed anyway.. the box is more of an organizer than anything.

    However I do not battle in deep ponds (8+ feet) and have not sank in water deeper than 4 feet since I started using these boxes. I sank once at the Brouhaha and once at Carl's and took on no water. I was planning on making a video about them as part of a modular / quick build so I don't have to re-tell/re-email for every new guy we get.

    The main reason I started using a box again was due to copper sulfate causing a green (what is that copper?) build-up on the receiver pins and for that matter on all red (positive) wires or pins in the ship. I am working on a plan for the servo connections outside and have tried many methods including mega-packing with dielectric grease with limited success. I have been looking to try waterproof connectors but they are large and expensive.

    Last year at the Brouhaha I had clean pins in the box.. so I feel like it worked.

    The seal on the box is from the tight fit of the plastic and it is not something I would open all the time. In the future I plan to put a pack of desiccant into the box for the odd drip.

    I have made 3 of these so far and plan to make more. My favorite box is the plastic box with tabs that you can screw down.

    All-electronics has a much better price that what I paid for my boxes which are about 3.5 x 2.5 x 1.5
    http://www.allelectronics.com/category/490/project-boxes/1.html

    Tabs - http://www.allelectronics.com/item/mbf-22/project-box-w/mtg-flange-5.12-x-2.68-x-1.72/1.html


    J
     
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  7. Lou

    Lou It's just toy boats -->> C T D <<-- Admiral (Supporter)

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    If you want, do what the sub guys build for their free flooding boats
    http://www.frontiernet.net/~bwelch/photo.htm
    You can buy the caps and tubes. Been using it for years with no issues. Of course like Johnny I waterproof all the electronics as well (defense in depth)
     
  8. NickMyers

    NickMyers Admin RCWC Staff

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    i see what you did there
     
  9. Maxspin

    Maxspin -->> C T D <<--

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  10. SteveT44

    SteveT44 Well-Known Member

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    I'm still liking my electrical box. No leaks in testing (8') and a couple test sinks at Greenbrier (shallow).

    [​IMG]
     
    Last edited by a moderator: Feb 14, 2017
  11. Manic Minion

    Manic Minion New Member

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  12. thegeek

    thegeek Well-Known Member

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    I have found that all the connections through the walls of the box and the connections too the boards are a failure point.
    I like to run wire through a opening in the box side and have two plates of Aluminum (one on either side of the box) that seal the box
    with RTV, this way if the wire wiggles the seal isn't broken. All those bolts and the holes that have to be there are a weak point.
    All of the electronics in my boats tend to be potted in West System after a liberal dip in Scotch kote. Then they are soldered to each other
    and the connection points are scotch koted, no screw connections, no jones strips, not easy to take apart but not necessary to take apart if it works.
     
    Last edited by a moderator: Feb 14, 2017
  13. SteveT44

    SteveT44 Well-Known Member

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    Not readily apparent but each of the through-box penetrations was sealed with green loctite (a penetrating sealer) on the threads and a bead of E6000 was run around each of the nuts. IMO the box would crush from pressure before any water gets past the wire connections.
     
  14. thegeek

    thegeek Well-Known Member

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    The issue of the "greens" getting to all the connections is what I try to fix with less connectors and connections. Steve your box will probably take a truck to crush it, so water hasn't a chance to breach the box. The issue of "easy to fix" is harder with everything soldered together and connectors make fixing it easier.
     
  15. SteveT44

    SteveT44 Well-Known Member

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    Many ways to skin a cat. That's what I like about these obscure hobbies (where everything hasn't been perfected down to a couple OTS solutions). For me, the engineering aspect is as much fun as the battling.
     
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  16. Evan Fowler

    Evan Fowler Well-Known Member

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    This is a great thread. Thanks guys, I found this very interesting and informative
     
  17. BigGunJeff

    BigGunJeff Well-Known Member

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    We epoxy everything and use waterproof servos, but I've always heard that the deep sea ROV folks use waterproof boxes filled with mineral oil. I tried that on a few servos as a test and it worked well. Mineral oil is pretty inert and doesn't hurt the electronics including the potentiometers. Makes a mess if you need to adjust things though...