Quote:
Originally Posted by sumoarigato
Why are acrylic tanks made with the side panes sitting on top of the base pane? My initial thought would be to do exactly what you did. It just "seems logical" to put the four panes above the base to fully support the pressure.
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Glen had it right about the shear strength of silicone being poor, requiring sides against the bottom, rather than on it. I screwed up, and that seems clear in retrospect. But I know why I decided to do it the way I did, and I'd wager dollars to doughnuts that it's the same reason acrylic builders do it...
When you set the glass around the outside of the bottom, the measurements of the side panes becomes much more critical than if you set them on the bottom. Think about it. When you are placing side on top of the bottom, you pin four sides together, and as long as they come close to meeting the edges of the bottom pane, you're OK. But when you wrap them around the bottom, if they aren't perfectly cut, you could have some nasty gaps, or the interior of the sides could be larger than the bottom. Bad problem.
Placing sides around the bottom is far less forgiving of small mistakes in cutting. But with acrylic, you just make sure the bottom is bigger than the connected sides... bond them on to the bottom, and trim any bottom edge excess with an acrylic cutting router bit. Much easier. And the whole shear vs. adhesion thing doesn't matter at all with acrylic, because once bonded, acrylic seams are actually stronger than the acrylic sheets.
BTW - did I mention that I'm doing work in acrylic now? Never without a project.
