300gal plywood paludarium project

JBR

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May 22, 2010
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I might have missed it but what is going in this thing? I would suggest lowering the water level a hair because the "w?" track for the glass to slide in can seriously annoy you when looking at inhabitants on the ground level of the tank. of course if the animals are above ground then it won't matter.

-John
 

the_deeb

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Apr 22, 2006
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Ok, I've been really busy with other stuff so progress has been very slow but here's a long overdue update.

As I mentioned earlier, I do not recommend using a mitered corner design like this. The joint lacks structural strength and it's very hard to get everything to line up. That being said, I decided to make the best of what I had and modified the edges to create sort of a haunched miter. This would offer a better supported joint with a much larger gluing surface. Here's the plan for how I hoped the edges would fit together.



I began by epoxying and screwing some 3/4" strips of plywood to the edges of all the pieces.



Next I applied a coating of epoxy to all the joints (first a regular coat to saturate the wood, followed by a second layer of epoxy thickened with Cabosil) and screwed them together with 1.25" and 2" wood screws as shown in the diagram above.



Here's a closeup of the joints to show how they fit together. There's a screw every 2" but they're spaced in an alternating pattern. As expected, the mitered part of the joints didn't fit together quite as perfectly as I'd hoped leaving a bit of a gap on the back edges where I couldn't produce much clamping pressure. I solved this by injecting epoxy resin into all the gaps to produce a solid, epoxy-filled joint.



For bracing around the top edge I installed some strips of 3/4" plywood. The front and right side are 4" wide with cutouts for future fan installation. The back and left side are 3". I attached the strips with Titebond III and pocket hole screws. This is really strong - I did a set of dips supporting myself just on the bracing and it didn't budge (though I admittedly don't weight very much)! Eventually I'm going to add an additional 3" center brace running from front to back.



Here's the tank flipped over and the bottom bracing installed. Here I used 1X3 poplar strips, epoxied and pocket hole screwed like the top. The difference here is that the strips were attached 3/4" away from the edge, so that once the 3/4" plywood bottom panel is installed it will be flush with the bottom edge of the sides. You can see the bottom panel leaning against the wall in the background, pocket holes drilled and ready to be installed.



That's it for now. I'll add some more updates when I get them off my camera.
 

dawnmarie

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Sep 21, 2009
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Did I mention I LOVE overkill ?

It looks good. Not a little, A lot.
 

the_deeb

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Apr 22, 2006
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Thanks guys.

wtf - yes I used the West Systems indoors (in a small, poorly ventilated apartment) and it wasn't bad at all. The fumes aren't strong at all, though lack of smell doesn't necessarily mean lack of toxicity, so I quite possibly killed some brain cells. The resin has almost no odor, but I've noticed that the hardener has been developing a slightly stronger smell over time.

Another thing to consider is that I've primarily been using the epoxy resin as an adhesive so I haven't been using very much of it. I've only been mixing up about 10-60mL at a time and applying it over a small area. If I was using it to really waterproof the tank and was spreading it out over large pieces of plywood I imagine the fumes would be worse.
 

the_deeb

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Apr 22, 2006
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Ok, I need some feedback. I'm planning on using Pond Coat / liquid rubber to seal the tank. My plan is to first seal the area around the viewing windows with epoxy, install the glass with silicone (GE1) and then paint over the epoxy and up to the edge of the silicone seal with the PC. This way, the epoxy forms a waterproof underlayer that bridges both the silicone and PC and I don't have to worry about issues of PC-silicone incompatibility.

seal1.jpg

This is similar to what BadOleRoss did (though I think he used fiberglass resin instead of epoxy).

OK, here's where I want some feedback - do you think that a few coatings of epoxy by itself will be sufficient to seal the area around the viewing windows or should I also use fiberglass cloth?

I don't have much space around the glass and frame that it sits in (maybe 1/8" at most), so I unfortunately can't add in a wide fillet to radius the corner. This means that if I do use the fiberglass it will probably have bubbles at the very edge since (I've heard - no personal experience yet) it is hard to work it into tight corners.

Keep in mind that (assuming everything does according to plan) none of this epoxy layer will be exposed - it will either be covered in silicone or covered in PC. That being said, will the addition of potentially bubbly fiberglass cloth be an improvement over just epoxy?
 

Clay

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Aug 28, 2005
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I was looking over your pics.... Great work and attention to detail. Judging by the uniform pattern for the pocket holes, I'm guessing you're using the same Kreg jig that I do... yeah?

Can't wait to see how the finished product!
 

Conner

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Dec 27, 2008
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I don't think you need the fiberglass cloth. That's mostly just for strength, and as far as I know adds nothing for waterproofing. As far as using the West Systems epoxy as a waterproof bridge under the pond coat and silicone edge, that's a good idea. People use that epoxy by itself for waterproofing tanks, so I imagine it would work fine in this application. **As long as the pond coat will stick to the epoxy, that is...
 
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