Acrylic Fabrication Q & A

[Iceman001]

Hi, wanted to do a rimless acrylic tank of 36" x 20" x 12", Is it safe? What's the thickness to use?

 

[Lowell Lemon]

Hi, wanted to do a rimless acrylic tank of 36" x 20" x 12", Is it safe? What's the thickness to use?

The formula recommends .472" or 1/2" cell cast acrylic for a rimless design.

 

[Turbo's Aquatics]

I'm not an expert on rimless tank thickness, I'll have to check. But my educated guess tells me 1" minimum for 12" tall, maybe 1.25"

 

[Turbo's Aquatics]

The formula recommends .472" or 1/2" cell cast acrylic for a rimless design.

I go up to 8" on a rimless frag tank that is 36" long, going to 12" tall IMO it would bow insanely and blow out the corner seam within a few years. What formula are you going by?

James had an opinion on those manufacturer formulas, IIRC it was that for a rimmed tank they went too thick, and for a rimless tank they recommended too thin.

 

[Lowell Lemon]

I'm not an expert on rimless tank thickness, I'll have to check. But my educated guess tells me 1" minimum for 12" tall, maybe 1.25"

Just curious why twice the formula thickness or more for this tank? I know there is some water absorption but only about 2%. Following the formula by Acrylite seems to be plenty of thickness for all designs top or not.

 

[Lowell Lemon]

I go up to 8" on a rimless frag tank that is 36" long, going to 12" tall IMO it would bow insanely and blow out the corner seam within a few years. What formula are you going by?

James had an opinion on those manufacturer formulas, IIRC it was that for a rimmed tank they went too thick, and for a rimless tank they recommended too thin.

Who is James? And I never had a corner blow out in the sumps or tanks built with Acrylite's or PolyCast's recommended formulas.

I guess you could add 3/4" tumble polished cubes to the corners for strength if you want more insurance.

 

[Turbo's Aquatics]

Just curious why twice the formula thickness or more for this tank? I know there is some water absorption but only about 2%. Following the formula by Acrylite seems to be plenty of thickness for all designs top or not.

That was just off the top of my head, it might be 3/4" but I think 1/2" for a 12" rimless is not enough.

That's based on my personal experience with 8" tall rimless frag tanks, 24x36 using 3/8" bowed badly, good enough for a sale tank at shows but not for permanent use, IMO. I moved up to 1/2" and no bow, good for permanent use. Based on that I just feel that 1/2" is not enough for 12" tall but that's JMO and it sounds like you have more experience so maybe that's just one of those "know what you're doing" things: built it right and you'll be OK, build it shoddily and you're in the danger zone.

Who is James?

James Steele, Envision Acrylics (he's on another board)

And I never had a corner blow out in the sumps or tanks built with Acrylite's or PolyCast's recommended formulas.

but then again, you build lots of things, so those seams are probably rock solid, made with mixed solvent vs pre-made, professionally prepped edges, etc.

 

[cromag27]

I made a 36 x 20 x 10 from 1/2" and it ended up bowing about 3/8". lasted a few years before I broke it down. sold it to someone else and haven't heard any issues with it. Even though I got away with 1/2" I didn't like seeing the bow.

 

[Iceman001]

Thanks, everyone for the advise, I think to be safe I'll go with 1/2" with 2" brace.

 

[Lowell Lemon]

Thanks, everyone for the advise, I think to be safe I'll go with 1/2" with 2" brace.

Never a problem when you use a brace or corner cubes. Let us know how it works out for you.

 

[Lowell Lemon]

@Floyd R Turbo

No problem I just wanted to know your experiance. And I have never crossed paths with James. Always open to learning...that is why I ask questions. Just because I may have been lucky does not mean I should not up my serve.

 

[cromag27]

The moment you pull the pins and the excess solvent squeezes out.

 

[mtswaneya]

The guys at my plastic supplier talked me out of switching from acrylic to polycarb because it's softer than acrylic and more prone to warping due to gravity.

Love the lids.

 

[cromag27]

Thanks!

 

[mtswaneya]

Guessing you have access to a CNC to make the lids?

 

[cromag27]

Nope. all handmade here! I have access to a cnc and laser cutter but I like to do it the old fashioned way.

 

[mtswaneya]

Nice. I need to try and make one for my tank. Have you made any post on them being made for reference?

 

[imustbenuts]

@Floyd R Turbo
Hey Bud, I glued up my first side and noticed the ends don't look clear like the rest. I was pretty careful with everything. What do you think? Will it be a problem?

 

[Turbo's Aquatics]

That's a pretty common issue I get also. The corners are the strongest point in the build so a little air creep like that is 1) hard to avoid (maybe someone has a tip?) and 2) when you put the top/bottom on and fill the joint with solvent, this area will get filled also. I'm sure there is a little trick to prevent that, like maybe blue painters tape (and scraping it off afterwards). But this is an example of why you use overage for a fillet: the seam is awesome all along the edge, then in the area where the 2 pieces are flush, that's where air gets in. If the whole joint were flush-fit, the whole joint would have air in it.

Long and short is, you're good.

 

[imustbenuts]

That's a pretty common issue I get also. The corners are the strongest point in the build so a little air creep like that is 1) hard to avoid (maybe someone has a tip?) and 2) when you put the top/bottom on and fill the joint with solvent, this area will get filled also. I'm sure there is a little trick to prevent that, like maybe blue painters tape (and scraping it off afterwards). But this is an example of why you use overage for a fillet: the seam is awesome all along the edge, then in the area where the 2 pieces are flush, that's where air gets in. If the whole joint were flush-fit, the whole joint would have air in it.

Long and short is, you're good.

Thanks for the reply Bud. I was worried. This being my first build I don't know what to expect. Keeping my fingers crossed.