Acrylic fabrication questions? I can help!

[Acrylics]

What is the quality difference between Cyro acrylic and Polycast acrylic?

Assuming Acrylite GP v Polycast
*Acrylite is metric Polycast is imperial thickness, so when ordering 1/2" Acrylite, you're actually buying 12mm or .472"and when their thickness tolerances are accounted for, your sheets will average in the .450" range. Polycast is spec'd at .500" and when tolerances are accounted for - generally around .480" IME. In both cases, thickness can vary, but these are average numbers.
*Acrylite has more thickness variation IME
*Acrylite will generally run on the thinner side of their tolerances
*Due to the way both materials are made, the thick and thin spots of the sheets will be different. Acrylite is made in an horizontal waterbath cell so will generally be thin in the middle of the sheet and thick on the perimeter. Polycast is made in a vertical cell so generally one end will be thicker than the other.
*Acrylite will generally have a higher higher mole wt than Polycast IME, this is especially apparent in colors. Higher mole wt makes it harder to glue and get "perfect" looking joints
*Acrylite makes their own MMA (base resin) while Polycast has been buying theirs from Lucite for the last 15-20 years, perhaps longer

The newer Acrylite is being made in China, don't know too much about the "new and improved" version of this material, havent' played with it. Everything above is based on the good ol' American material. If you buy the Acrylite, just check the inspection sticker to see where it was made.

HTH,
James

 

[chriscobb]

Thanks James.....

 

[vthondaboi]

How about a Plexi G and Lucite L vs the above Polycast and Acrylite GP? :wavehand:

 

[blackizzz]

If you want to build an ozone safe skimmer, can you use any cell cast acrylic ( good ) or is it any special acrylic for that???

 

[blackizzz]

bump

 

[Lofty]

Sump = FAIL

Sump = FAIL

Ok, good thing for Reef central as I have realized that my Sump design is extremey flawed, although I don't Know exactly why... just had several replies about it being a cool idea but using silcone to bond acrylic is a bad idea.

Here are some pics of my design... unfortunatly already impemented and will need redesign.

I used 3/8 inch acrylic fro the front and right side and a thinner acrylic for the back, floor and left side as they are suppoted by the plywood. I used # II door and window GE silicone to seal and joint bonding. It seems solid as a rock even after only 4 hours of curing. What is wrong with the design and how do I fix it... if I need to use glue, I can stripp all the silicone out of the joints and glue it and reseal it with the silicone.

Thanks in advance for the help.

 

[noobtothereef]

ge number 2 is bad news, its has an anti mold agent in it and will affect your tank inhabitants, i would scrap the entire things and start over

 

[Lofty]

ge number 2 is bad news, its has an anti mold agent in it and will affect your tank inhabitants, i would scrap the entire things and start over

Only the kitchen and bath version has the anti mold additive...

 

[blackizzz]

bump =)

 

[Acrylics]

If you want to build an ozone safe skimmer, can you use any cell cast acrylic ( good ) or is it any special acrylic for that???

Are you talking about the tube or sheet stock? in either case, no special acrylic. Standard spun-cast tube and cell cast sheet stock will be fine, though I'd expect ozone to degrade the material faster than it normally would.

I used 3/8 inch acrylic fro the front and right side and a thinner acrylic for the back, floor and left side as they are suppoted by the plywood. I used # II door and window GE silicone to seal and joint bonding. It seems solid as a rock even after only 4 hours of curing. What is wrong with the design and how do I fix it... if I need to use glue, I can stripp all the silicone out of the joints and glue it and reseal it with the silicone.

Thanks in advance for the help.

Silicone sticks to acrylic but not nearly well enough for any structural applications. The silicone needs to be removed, the areas cleaned with denatured alcohol, machined to size then glued together using a methylene chloride based solvent such as Weld-on 4 or a 2 part cement such as Weld-on 40.
Do not reseal with silicone, it will do absolutely nothing to strengthen the joints in any way.


HTH,
James

 

[blackizzz]

Thanks!
Talking about both, but how fast would the materials degrade without ozone, last for 5+/10+ years?

Thanks for all your help.

blackizzz

 

[Acrylics]

Thanks!
Talking about both, but how fast would the materials degrade without ozone, last for 5+/10+ years?

Thanks for all your help.

blackizzz

The material will pretty much not degrade in my lifetime without ozone. But the addition of ozone is like adding UV - it's an oxidizer/aging accelerant that may bring the material down to the 5 yr range. What happens is the material will simply become more and more brittle over time, similar to the cracking you'd see in old tires and gaskets. This is not a real concern to me, but just me - you rarely see these types of apperatuses in service this long anyway

The only part that concerns me at all is how well the fabricator does his/her job in gluing. IME UV degrades joints and other stress points faster than the material and I'd expect ozone to be no different.

HTH,
James

 

[blackizzz]

Ok, Thanks. so it would work a while =P if i glue well? thats good to know. =) thanks for all your help.

 

[Bore-Punch]

James, excellent thread here I appreciate you sharing your wealth of experience with us.

Was wondering if you could quickly verify my tank designs as structurally sound. Im planning on using ACRYLITE® GP. based on your recommendations in this thread.

all tanks made with 3/4" material

DT = 72"X25"X30.5" 2" eurobrace with a 6" centerbrace (using a surge device is constantly going to be pumping water in and out of the tank adding a dynamic component to the loading as well, about 40gal or about 320# in and out of the tank)

refugium = 36"X24"X24" with 2" eurobrace

Sump = 36"X18"X24" with 2" eurobrace made from scrap ie not a single piece
Sump#2= 18"X18"x24" with 2" scrap eurobrace


Chemcast GP fails alot in your experience as well? I guess that rules out purchasing my acrylic from Delvies.

Thank you for your time.

 

[Acrylics]

Was wondering if you could quickly verify my tank designs as structurally sound. Im planning on using ACRYLITE® GP. based on your recommendations in this thread.

all tanks made with 3/4" material

DT = 72"X25"X30.5" 2" eurobrace with a 6" centerbrace (using a surge device is constantly going to be pumping water in and out of the tank adding a dynamic component to the loading as well, about 40gal or about 320# in and out of the tank)

Assuming L x W x H? if so; I'd increase the perimeter flange (aka eurobrace) to 3" and add a 2nd crossbrace, so you'd have 3 top openings - each measuring 18 x 19". Or increase the perimeter flange to ~4.5" and keep the one center-brace. Make sure the top is one piece, and the openings have a 1-1.5" radius (minimum IMO)
This is how I build my tanks and advise the same. Structural integrity is #1 priority but one has to be especially mindful with dynamic loading

refugium = 36"X24"X24" with 2" eurobrace

Sump = 36"X18"X24" with 2" eurobrace made from scrap ie not a single piece
Sump#2= 18"X18"x24" with 2" scrap eurobrace

assuming these are all 3/4" as well? If so, I'd probably just increase the perimeter flange width to 3" on the 36" spans. One would prefer to use 1 piece tops with a good radius in the corners, but since you're using 3/4" material - will help.

Chemcast GP fails alot in your experience as well? I guess that rules out purchasing my acrylic from Delvies.

It's an odd deal with Chemcast. I know the company that makes it and the plant that makes it and the people that built the plant. In theory, it should be every bit as good as Plexi-Glas G, but I've seen far too many tanks fail that were built from this material. I can't say if they're over-polymerizing it or what this issue is, but the joints just suddenly fail after a coupla years under load, even if well designed and engineered.

There *was* a company that was around for a few years building tanks exclusively from this material. Great pricing and they did a good job for a while, even offered lifetime replacement guarantee. After 2-3 years, the returns started coming in and they folded not long afterwards..

I know it's cheap compared to others, but I won't even allow it in my shop, much less advise it for a pressure vessel.

HTH,
James

 

[Bore-Punch]

Exactly what i was looking for thaks a ton James, will probably have more questions in the future when I actualy attempt this . Thanks again.

 

[110galreef]

Building frag tank:

36 x 30 x 10 all 1/2 acrylic. Need top bracing? waterline should be about 8.5" high & net about 38-40g. I am also putting an external coast to coast overflow on the back that will span only 24" so I have room to bring a return in.

Also plan to glue with weldon 4. right stuff?

DO i need to do the pin method or will just resting the panels in place on a 90* angle suffice to get the weld on in there?

Everything is cut just waiting for the glue?

 

[Acrylics]

Building frag tank:

36 x 30 x 10 all 1/2 acrylic. Need top bracing? waterline should be about 8.5" high & net about 38-40g.

IMO, yes

Also plan to glue with weldon 4. right stuff?

it'll be fine

DO i need to do the pin method

always

 

[110galreef]

Ok, thanks,

3/8" acrylic, and 2" perimiter plenty for the eurobrace

I am out of 1/2", yet could possible brace it with 4 scrape pieces of 1/2".

Thanks for the advice

 

[Acrylics]

Ok, thanks,

3/8" acrylic, and 2" perimiter plenty for the eurobrace

I am out of 1/2", yet could possible brace it with 4 scrape pieces of 1/2".

for this size tank, either would be fine

James