I seems that over the years junction boxes have been tried and rejected for use as a waterproof box. The common problem seemed that the lid wasn't rigid enough to create a waterproof seal. I stumbled across this today. http://www.allelectronics.com/item/1590-lb/diecast-aluminum-enclosure-50.0-x-50.0-x-31.0-mm/1.html I would think that you wouldn't have to worry about flex with the aluminum lid, so you should be able to create a good seal. Any thoughts?
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.
Oh yeah, I have enough trouble keeping my boat working reliably as it is, now I have to refit it to withstand and EMP.
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
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)
The only place I have seen these fail is a poorly sealed popit valve hole. They are made to open. This is one place that I don't scrimp. once I went to solenoids, I have never had one leak. http://www.gsioutdoors.com/shop/base-camp/storage-protection/lexan-s-gear-box.html
I'm still liking my electrical box. No leaks in testing (8') and a couple test sinks at Greenbrier (shallow).
What are your thoughts on using something like this ?? i use it to house electronics for outdoor skirmish, never had a leak or water inside the box yet, and have been playing in torrential rain multiple times, http://www.altronics.com.au/p/h0325-ritec-145lx105wx45hmm-ip65-sealed-abs-enclosure/
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.
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.
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.
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.
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...
