The real RC submarine model gurus will probably tell me I´m crazy, but they´ve told me that before.
Here is the beginning of the watertight container (WTC) for my propulsion unit. It was constructed from Celtec and then glued and screwed. Plans are to seal the seams with something else as well; either epoxy or liquid something-or-other (not sure about that one.)
The lid was cut from a sheet of polycarbonate (Lexan®), and is just laid on top for now. I cut it larger than the box because I haven´t decided how it will be attached yet.
The box walls are 3/8" thick and will probably hold studs, but if I do that there probably won´t be enough room for an o-ring seal. I could simply put a rubber gasket on the lip, but on the other hand, it may be even better to place some studs outside of the box walls. That would, of course, entail adding a stud lip around the outside edge.
Well, its time to think about this one for a while. I want to get this part right because much of my wife´s hard-earned money will go down the drain if I don´t!
In the meantime however, John (at Norva Plastics, Inc.) is working up an estimate to have my WTC´s manufactured out of 3/8" or ½" polycarbonate. I´ll let you know which way I decide to proceed.
I haven´t heard from John at Norva Plastics, Inc. yet so I´ve decided to make at least one of my required two WTC´s. As you can see here, I trimmed the clear polycarbonate (Lexan®) to just larger than the box itself. I also drilled one starter hole in a corner and taped the other side to hold the top in place.
Before I go any further, let me explain why I´m drilling the holes this way. Some of you might ask ... "wouldn´t it be better to drill the box first and then the clear top so as to not scratch the top?" And ... "don´t the holes in the clear top have to be larger in diameter than the ones in the box?"
Whelp, the answer to both questions is an obvious Yes! But, if I drilled them separately, they would certainly not line up. So ... I elected to drill through the clear top first with a drill bit for the box ... and then drill into the clear top again with a slightly larger drill bit.
|Here I´m using a drill press to drill the first holes through the clear top and into the box. The drill bit is slightly smaller than the 8/32 X 1½ bolts I´ll be using. As I drill each hole, I´m also placing a smaller screw into the holes to keep the top aligned.|
|Next, I´m drilling through the clear top again using a slightly larger drill bit than the bolts. As you can see, I´ve also taped over the previous holes to cut down on the chipping of the Lexan®.|
|Now the holes have been drilled and I´ve installed the fourteen (14) 8/32 X 1½ bolts. As you can see, I´ve also placed nuts on the bolts before screwing them in. This precaution was to help in cleaning the threads after the bolt heads were cut off using my Dremel® tool. And ... it actually worked. Some of the bolts had little burs, and backing the nuts off removed them.|
|Ok, here you can see the wing nuts, washers and lock washers have been installed. The only thing left to do now is manufacture an O-ring gasket. I bought some stuff at Boat U.S. yesterday for that purpose, but won´t identify the product until I´m sure it works. So until then ...|
I couldn´t resist the temptation. Here you can see the rear WTC inside the bottom half of the hull. It´s just sitting there for now, but you can see it´s approximate location.
Next Step - Part 3 - Watertight container (continued).
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Last Updated Thursday, February 20, 2003 4:38:03 AM