what is the difference b/w cast and extruded acrylic?

[surfn]

which is the kind that you can cut and glue to make tanks with?

just curious, i need to buy a small flat piece to put over my external overflow to block the salt spray, 1/4" thick. i've gotten some from McMaster-Carr before several years ago to make overflow boxes, I just can't remember what kind it was...lol

links are VERY helpful, as the McMaster-Carr site is wicked confusing...lol

 

[J. Montgomery]

If all you want is a piece to sit over the overflow, you can buy a piece of acrylic from Lowes (I've got an acrylic scoring knife if you want to use it). If you're wanting to glue it, I dunno.

 

[chadfarmer]

cell cast acrylic is what you want


extruded absorbs more water and is not as sturdy as cast

 

[mbunaman]

Extruded means pressed through a machine and then trimmed. So in reality its less dense and may have weak areas in it from manuafacturing. Cast means it was poured and pressed so the density is tighter. You want Cast. Dont buy extruded it will fail in due time.

 

[surfn]

If all you want is a piece to sit over the overflow, you can buy a piece of acrylic from Lowes (I've got an acrylic scoring knife if you want to use it). If you're wanting to glue it, I dunno.

that stuff will warp like crazy under light, heat, and salt spray. plus they don't have anything as thick as 1/4" i believe.

thanks ya'll.

 

[twon8]

they do have 1/4" at lowes, ive used it

 

[surfn]

btw, are there any special types of radial saw blades for acrylic? links would be helpful.

this would attach to a table saw. not sure on the diameter of the blade though, but i can find out if need be.

 

[chadfarmer]

there is special blades for acrylic (not cheap if I remember)

you can you a normal blade but it will melt it

I have no links I use the blade we have at work that is designed for corian

 

[twon8]

i've cut 3/8ths with a chopsaw. just go a little at a time, take it slow

 

[fade2black]

You can use a standard woodworking blade. Just use one with at least 80 teeth. ATC is the best grind, however any of them will do. Go slow, but not too slow or heat will build up and it will melt. Cast acrylic machines MUCH better than extruded.

 

[fade2black]

Oh, and just to add, unless this is right under a 400W metal halide, a light isn't going to make it warp. Acrylic warps because one side is subjected to a very moist environment so that side absorbs more moisture than the other side, which causes the warpage. I have done years of testing on my vivariums to fight this. Thickness really has no effect as I have used up to 3/8" and it still warps. The best thing is to reinforce it so it can't warp.

 

[surfn]

i had a clear piece of 1/4" cast acrylic i got several years ago that i used as a cover for a tank. that thing ended up warping substantially.

 

[J. Montgomery]

I've had a cover over my preskimmer box for about a year now. One side of it is UV resistant, and I painted it with Krylon fusion. No signs of warping yet.

 

[fade2black]

I have never heard of or seen of acrylic that is UV resistant on one side. Just about all the acrylic you buys is UV blocking. You have to get acrylic specifically made to pass any UV, such as OP-4 or Solacryl which is commonly used in tanning beds. The way the monomer is formulated it either is or isn't UV resistant. However, I have seen acrylic that is scratch resistant on one side, but that is a coating added after the casting process.

 

[J. Montgomery]

Ok, so what I'm calling acrylic most likely isn't really acrylic. I'll check the label when I get home and get back to you. But whatever it is, its definitely UV resistant.

 

[surfn]

However, I have seen acrylic that is scratch resistant on one side, but that is a coating added after the casting process.

yeah, i saw that too. is it aquarium safe?

 

[fade2black]

You can't create a joint on the scratch resistant side. The solvent won't bond the acrylic due to the coating, otherwise it would be perfect for reef tanks!

 

[fade2black]

Ok, so what I'm calling acrylic most likely isn't really acrylic. I'll check the label when I get home and get back to you. But whatever it is, its definitely UV resistant.

Your standard cell cast acrylic is UV stabilized and blocks just about all UVA, UVB, and UVC radiation. That is why it doesn't yellow and become brittle on aquariums and when used as windows, etc.

 

[Russellaqua]

If it's just an overflow box you want to make 1/4" extruded acrylic from any major hardware store is ok. It can be cut with a very fine tooth blade and take it slow or it'll chip like crazy. Cell cast is needed to make large tanks. The best glue is called Weld-On #4. It's a thin solvent that actually melts the acrylic together, essentially forming them into 1 piece. It creates an extrememly strong joint, and because it's so thin you can put your pieces together into the final shape and capillary action will draw the solvent into the joint. I've actually built a 20L tank this way, but wouldn't go any larger with extruded acrylic, and I still had to brace the top.

 

[surfn]

If it's just an overflow box you want to make 1/4" extruded acrylic from any major hardware store is ok. It can be cut with a very fine tooth blade and take it slow or it'll chip like crazy. Cell cast is needed to make large tanks. The best glue is called Weld-On #4. It's a thin solvent that actually melts the acrylic together, essentially forming them into 1 piece. It creates an extrememly strong joint, and because it's so thin you can put your pieces together into the final shape and capillary action will draw the solvent into the joint. I've actually built a 20L tank this way, but wouldn't go any larger with extruded acrylic, and I still had to brace the top.

i have an acrylic tank built out of 3/8" w/ eurobrace and external overflow. i had it custom made locally. all i'm doing is cutting a piece that will look nice w/ the tank to cover the top of the over flow box to prevent salt spray from hitting the back wall. nothing exciting, but its a nicely built tank and i don't want to do it ghetto style as i will most likely sell it some day.