optical quality of bent acrylic

[tedskala]

I'm planning on building a cylindrical tank by bending cell cast acrylic (40-48 inch diameter). Will the optical quality be good on this tank, or will it distort the contents of the aquarium? Perhaps the reason the cylindrical tanks are so expensive is because they have to be cast in the final form and not bent. Or maybe they don't think customers would want a seam (I can live with one seam if I save $2000). Also it seems this bend should be easy because it is a long radius. Does anyone have any experience with this type of bend?

[Geoff]

Welcome to TRT!!!



i have never really seen a curved tank that did not distort the daylights out of what is in the tank. is there a reason you are wanting round beside aesthetics?

G~

[sasquatch]

It will be like a fun house mirror, theres no way to control the edges so as it wraps around the plug its trying to become an hourglass. I really like the look of a round tank but woohoo what a pile of money

[tedskala]

I'm not sure what you mean by "wraps around the plug". I would have to wrap it around a cylinder, so I don't see how that can produce an hourglass shape.

I talked with an engineer from Polycast on the phone for about half an hour today about various issues with this project. The distortion shouldn't be a problem, he says, as long as the material is a uniform thickness all the way around. But he is worried about stress on the material because I am not heating the whole piece an once in an oven. My idea is to lay the cylinder template on it's side and place the acrylic on top (so it looks kind of like a see-saw, with the template as the fulcrum, and the 12 foot long acrylic sheet balanced on top with 6 feet on each side). I only need to heat the portion of the acrylic that is a fraction of an inch above the surface of the template. When gravity causes the acrylic to slump against the cylinder, I move the heat outward. But he thinks because I am not heating both sides of the material it will stress. Maybe I will get a long scrap piece and experiment. If it doesn't work maybe I will try octagonal

[Geoff]

i would think that as long as you keep rotating the heat source around the entire surface than i would think that the stresses would be equal by the time you are done.

G~