Extrude acrylic for internal overflows

murph

murph

Active Member
Still hemming and hawing around about my tank build project. After finding a good price on cut pieces of cell cast acrylic I am pretty sure the new tank will be acrylic. Acrylic project by my calculations actually comes in at or slightly below cost for plywood build.
Only problem is the quote I requested did not include amount for pieces needed for the planned internal overflow nor are the overflow plans finalized.
Question is if basic hardware store extrude acrylic can be used for overflows once tank plans are finalized? Likely overflow configuration will be 2 internal towers at 5x6x18.
Planned tank demensions are 48Lx30Wx18H. 3/8 cell cast.
I plan on usein pin method to weld peices and practiceing this by constructing the overlows first out of cheaper extrude would be nice.
 
phixer

phixer

Active Member
You will see some bowing at 18" tall, much of this can be eliminated by using the same thickness for top and bottom though.
Some folks use thinner material for the top and bottoms to save in costs, almost always this will cause the sides to bow and eventually warp.
Acrylic is right though, you would be better off with thicker material. Contraction rates for extruded are also different than cell cast because it is squeezed (extruded) during the MFG process usually through rollers for sheet stock. Because of this, extruded acrylic is under more tension. Unless its annealed in a special oven it is more prone to cracking at the welds if bonded to cell cast. The two will bond together but if you can, you would be better off using all cell cast. Sounds like a great project, would like to see how it turns out.
 
murph

murph

Active Member
Thanks much for the advice guys.
I have not ordered the pieces yet so I will just go ahead and make sure I get cell cast for my overflows so that issue is solved.
As for the bowing I certainly don't want this so what are my options other than moving up to 1/2 inch which will significantly add $ to the project.
All panels will be the same thickness. 3/8
Reduce height of tank to say 16 inches?
and or rather than slat bracing at the middle sides and ends use a full sheet of acrylic with cutouts for top of tank; adds about 15 percent cost which is acceptable.
or add another center brace i.e. two end braces and two in middle spaced a couple of feet apart? Recommended width of braces??
Hopefully I can find some weld on locally this weekend and experiment/practice with welding. I install wood floors for a living and have access to professional quality tools for other aspects of the project. While I am here what would you guys suggest for drilling holes for overflows. I have a feeling hole cutters for this application may be hard to find at the home labyrinth.
 
acrylic51

acrylic51

Active Member
1/2" would be your best material choice......even using 3/8" and doing eurobracing your going to see flex.......it's your length not necessarily the heigth........Even though 1/2" will set you back alittle more it will be a more trustworthy structure........
There's a thread on the other site a guy did a 10 gallon nano and 1/2" was used as well.....again it's constant pressure unlike a sump where you could get away with 3/8" since it's not constantly full all the time......HTH
 
phixer

phixer

Active Member
Originally Posted by Murph
Thanks much for the advice guys.
I have not ordered the pieces yet so I will just go ahead and make sure I get cell cast for my overflows so that issue is solved.
As for the bowing I certainly don't want this so what are my options other than moving up to 1/2 inch which will significantly add $ to the project.
All panels will be the same thickness. 3/8
Reduce height of tank to say 16 inches?
and or rather than slat bracing at the middle sides and ends use a full sheet of acrylic with cutouts for top of tank; adds about 15 percent cost which is acceptable.
or add another center brace i.e. two end braces and two in middle spaced a couple of feet apart? Recommended width of braces??
Hopefully I can find some weld on locally this weekend and experiment/practice with welding. I install wood floors for a living and have access to professional quality tools for other aspects of the project. While I am here what would you guys suggest for drilling holes for overflows. I have a feeling hole cutters for this application may be hard to find at the home labyrinth.
16 inches with 3/8 is close if you dont want much bowing. I would definately use a full sheet for the top with two access holes cut out . Use gradual radiused corners for the cut outs. The full sheet is much stronger than any type of perimeter (euro) bracing or cross member support and the rounded cut outs will spread out the stress more evenly reducing the chances of it cracking at a 90 degree corner. To drill holes in acrylic I rest the plastic on a sheet of stryrofoam over plywood on top of 2 sawhorses in the yard then use a hole saw with a water hose running over it to keep it cool.
 
murph

murph

Active Member
Thanks again guys. If nothing else these past couple weeks of researching the project have been enlightening.
The whole point of it is to end up with a shorter wider tank. Shorter to make lighting needs easier to provide and wider to provide more floor space for a wider assortment of corals.
You would think with the popularity of reef style aquariums that dimensions like what I want to build would become standard. Unfortnatly the more pressing issue for tank manufactures appears to be keeping the waste factor down.
I don't quite even understand that as most of the waste could be utilized or sold off to the hang on overflow guys and in the case of glass used as baffles for sumps. :thinking:
In the case of my particular project I am going to take your advice and go with half inch. This may put the project on hold for awhile. I am off today and am going to try to find a local supplier for the acrylic. My hunch is they will not want to or be able to match the online price even considering shipping cost.
Hopefully the tank will eventually get built. From the prices I have seen on standard dimension acrylic tanks, buying the material and building my own will still represent a substantial savings especially for the dimensions I want.
 
acrylic51

acrylic51

Active Member
To bad your in Florida.....2 of my best friends own an acrylics place and I'd take you in and get you the hook up......
 
murph

murph

Active Member
As suspected getting the material locally means getting ripped off.
All suppliers want a 100 percent mark up. A half inch 4x8 sheet Internet $115. Local retail $229. I honestly don't know how they expect to sell raw materials like this at that kind of mark up. If they do sucker someone into a price like that eventually they will figure out how bad they got suckered and that customer is unlikely to ever buy again. Truly bad business practice IMO.
Finding weld on products locally has proven to be impossible also. Starting to look like I may be returning to my original plywood construction plans with an acrylic front.
 
phixer

phixer

Active Member
Murph there is a company called Caseway out of Orange park FL. They make a product called SC94 it is a high quality solvent cement similar to #4. I know several folks who claim it to be a superior product, maybe you could check it out.
If you do decide to go with the plywood/acrylic combination you also might want to consider a product called Sanitred. It's basically a liquid polyethelyne/rubber sealer that can be applied in any thickness, has the consistency of a truck tire when dry and works great on wood or concrete. Randy is very good about replying to email questions also. Im going to be using it on my next plywood/acrylic project.
Caseway Industrial Products, Inc.
1050 Green Pine Circle
Orange Park, FL 32065
Phone 904-214-9056 Fax 904-375-2439
email tsbrawner@comcast.net
http://www.caseway.net
 
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