Acrylic Fabrication Q & A
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Riley S
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Thanks for the reply. The acrylic thickness calculators I'm referring to are the kind for calculated the thickness needed for a tank, where you select braced or not, and it tells you the thickness needed. There was one referenced earlier in the thread. SD Plastics has one, for example.
Since the window in an frp, concrete, ect, isn't structural, how is the thickness calculated? I do understand that overall height of the tank would affect it, as would the placement of the window.
I imagine normal cleaning as to the deflection rates.
OP
OP
the issue with those calculators is that they are usually not very accurate. James went into a dissertation about why several years ago but I can't recall it exactly. Basically one calculator was way too conservative and the other way too liberal (not politically, thank God)
But for your specific example, I would provide very specifics detail on the tank construction
I think you're referring to Cyro's old calculator which was extremely flawed in a number of ways, and they know it, but that's another story..
Thickness in this case is calculated purely on height, span, pressure, and method of attachment. You can pull out some tech info from your acrylic mfr and Rourke's Formulas for Stress and Strain. Or you could just throw a window size at me along with window placement and tank height and I could tell you
As an example; a 48 x 96" window in most any tank in the hobby with a 3" rebate and contact area will require at least 1" - which will hold, but bow. 1.25" will have less deflection, but will be the suck for cleaning with a scraper if a reef tank. For a reef tank in which you'll be scraping coralline, I'd recommend 1.5" or better.
HTH,
James
Looking for few second opinions. I am welding a coast to coast overflow on the back of a tank. The length is 40" the height is 12". The material is 1" cast. So internal size is 38"x 11". I plan to keep it about 1/2 to 3/4 full when running. Should I add triangular braces under each end and or maybe a third in the center for added strength?
My plans comments please.
I wanted to build this all myself : stand, sump, frag tank and main tank.
I wanted the stand to house the tank and frag tank and tied to the same sump.
The frag tank is going to be 6 or 8 inches high and 20"x20: rimless maybe 24"x24" Is 1/2" overkill?
The sump in gong to be 33″ long x 15″ wide x 15″ high I was going to use the rest of the 1/2" from frag tank and make the inside panels 3/8 and hopefully rimless? overkill using 1/2"?
Now the tank I want 48"x30" x 20" I have used the calculators and one calculator say 1/2" says it is fine with framing and other says 3/8 is fine. I want to use either euro or just a brace down the middle. Problem is 3/4" is 487.00$ and would require 2 pieces. That is more than I wanted to spend. I do not feel 1/2" is enough and should be 3/4".. Anyway to do this and save a little money. Maybe use 1/2" bottom and framing and 3/4 for the sides? Still is allot of money. I could reduce size some?
Are there more charts or calculators for acrylic other than garfs and http://diyfishkeepers.com ?
My choices locally for Plexiglas-G is 62x96: 1/4 214.00, 48x96: 3/8=240.00, 1/2" 322.00 and 3/4" 488.00 sound reasonable. 10.50 per 1/2 hr to cut.
I wanted to build this all myself : stand, sump, frag tank and main tank.
I wanted the stand to house the tank and frag tank and tied to the same sump.
The frag tank is going to be 6 or 8 inches high and 20"x20: rimless maybe 24"x24" Is 1/2" overkill?
The sump in gong to be 33″ long x 15″ wide x 15″ high I was going to use the rest of the 1/2" from frag tank and make the inside panels 3/8 and hopefully rimless? overkill using 1/2"?
Now the tank I want 48"x30" x 20" I have used the calculators and one calculator say 1/2" says it is fine with framing and other says 3/8 is fine. I want to use either euro or just a brace down the middle. Problem is 3/4" is 487.00$ and would require 2 pieces. That is more than I wanted to spend. I do not feel 1/2" is enough and should be 3/4".. Anyway to do this and save a little money. Maybe use 1/2" bottom and framing and 3/4 for the sides? Still is allot of money. I could reduce size some?
Are there more charts or calculators for acrylic other than garfs and http://diyfishkeepers.com ?
My choices locally for Plexiglas-G is 62x96: 1/4 214.00, 48x96: 3/8=240.00, 1/2" 322.00 and 3/4" 488.00 sound reasonable. 10.50 per 1/2 hr to cut.
Nope, should be good.
No overkill at all, but I don't know your sump design. If you have some baffles - you may get away with rimless, but without some baffles - asking for problems. FWIW, I simply would not build it without some other structure added, either baffles or a perimeter flange.
You will need a perimeter flange, period. Whether you should have a center brace depends on your tolerance for bracing and wallet. Using 1/2" with 3" perimeter flange, you will need a center brace. With 1/2" and ~5" perimeter flange, you can do it without the center brace. Or if you wanted to use 3/4" for the vertical panels, you can use a 3" perimeter flange without a center brace.
3/8" is out of the equation IMO if this is to be a reef tank. Most complaints about acrylic are related to scratching. 3/8" will bow more than you want and you'll be scraping coralline with a flat scraper. Think flat scraper against concave surface and you can see how many, if not most scratches are incurred.
May be a chunk of change, but for what you're getting - cheap..
I've never seen a "thickness calculator" that wasn't the suck.
Prices seem reasonable enough.
Personally, I'd use 1/2" for the lot and use a center brace on the main tank. You're be spending $720 or so at most, and have a display tank, sump, and frag tank out of it with some extra material to practice on.. not bad. The center brace really does add a lot of structure. If you just can't live with the center brace, use 3/4" for the vertical panels of the display tank and 1/2" for the remainder. In this case, you'd be spending $1000 for the lot.. still cheap
To give you an idea about bowing; my last display tank in my office was 60x24x24" using all 1" Polycast, 3" perimeter flange and it still bowed almost 1/8" on each long panel. Not bad, but pushing my tolerances..
HTH,
James
Nope, should be good.
No overkill at all, but I don't know your sump design. If you have some baffles - you may get away with rimless, but without some baffles - asking for problems. FWIW, I simply would not build it without some other structure added, either baffles or a perimeter flange.
You will need a perimeter flange, period. Whether you should have a center brace depends on your tolerance for bracing and wallet. Using 1/2" with 3" perimeter flange, you will need a center brace. With 1/2" and ~5" perimeter flange, you can do it without the center brace. Or if you wanted to use 3/4" for the vertical panels, you can use a 3" perimeter flange without a center brace.
3/8" is out of the equation IMO if this is to be a reef tank. Most complaints about acrylic are related to scratching. 3/8" will bow more than you want and you'll be scraping coralline with a flat scraper. Think flat scraper against concave surface and you can see how many, if not most scratches are incurred.
May be a chunk of change, but for what you're getting - cheap..
I've never seen a "thickness calculator" that wasn't the suck.
Prices seem reasonable enough.
Personally, I'd use 1/2" for the lot and use a center brace on the main tank. You're be spending $720 or so at most, and have a display tank, sump, and frag tank out of it with some extra material to practice on.. not bad. The center brace really does add a lot of structure. If you just can't live with the center brace, use 3/4" for the vertical panels of the display tank and 1/2" for the remainder. In this case, you'd be spending $1000 for the lot.. still cheap
To give you an idea about bowing; my last display tank in my office was 60x24x24" using all 1" Polycast, 3" perimeter flange and it still bowed almost 1/8" on each long panel. Not bad, but pushing my tolerances..
HTH,
James
First let me say thank you for taking the time..
Sump will have baffles..
I am a little confused on the tank and I just want to be sure I got this right.
You mention 3/8" for main tank but never mentioned this size, I only said I wanted the sides to be 3/4" with the bottom being 1/2" and the top bracing 1/2". But I do understand even this route I need to at least 3" perimeter 1/2? with no center but a center will help. Now I can do this with strips right (euro bracing), it does not need to be a solid top with holes routed out?
If I use 1/2" on all sides I need 3" perimeter brace with center brace(which size center brace?)
5" perimeter means no center brace.
You are suggesting just doing all frag, sump and tank out of 1/2" is that correct?
How about no perimeter and just a center brace for the main tank? What would your suggestion be?
I saw a 120 this way. I actually prefer center to perimeter. One some smaller tanks I have made I have just glued in little triangles in the upper corners to help with corner strength.
I also like to over build just in-case especially if I made it. Failures stink. i usually use double whats needed.
Also I see these tops for acrylic aquariums with the nice rounded cut outs for access? How are they done? I am assuming a router strait bit but the nice rounded corners how are they done? Jig of some kind?
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I mention 3/8" as you mention one of the "calculators" said it's fine.
3/4" vertical panels (all 4 sides) and 1/2" top and bottom is just fine. You may go down a little on the perimeter on the all 1/2" tank, but not much. On tanks, if anything - I err on the side of caution.
Correct. And I use 6" as center braces, it yields nice round numbers. Like in your tank, a 3" flange and 6" brace yields 2 openings measuring 18 x 24"
That's what *I* would do. You may have different goals or desires or preferences
I'd pretty much say no unless you wanted to step up to 1"+ material, and at 1.5" you could do rimless... if you wanted to spend the money
This is acrylic, unless you want to spend the money or run the risk, bracing is going to be to the longevity and aesthetics of the tank. Adding *just* a center brace is helpful, but I simply wouldn't, again, unless you wanted to spend the money.
Either on a CNC or with a template and flush cutter, which is what I do.
HTH,
James
OP
OP
That's the blade I use for rough cutting. You will still want to use a router for edge prep.
To back up what James said, the 24x24x8 frag tank (which will likely see only about 7" of water) 1/2" rimless will do nicely. I've made several 36x24 rimless frag show/sale tanks with this height. 3/8" bows a bit too much for my tastes so that can't be used for constant use IMO, so I started using 1/2" which is not really that much more.
For the sump, if you want to do that rimless, I would go with 1/2" but again this depends on the baffle placement, height, and quality of construction method (i.e. are the baffles bonded in such a way they can be considered structural components). You could go with 3/8" if your baffles are structural and positioned to essentially divide the tank into smaller tanks, and your worst-case scenario water level doesn't present an overstress situation (that's all part of the planning). I have built many sumps using 3/8" but in most cases I try to add in a euro of some type, even if it's relatively small (like a 1.5" perimeter euro out of 1/4"). I also do 1/4" bottoms on most 3/8" sumps, unless the material useage means I can use a full sheet of 3/8". I use 3/8" baffles for "pressure" baffles, where there is a water level difference between each side, and 1/4" for separator baffles that have no water level differential (like the "up" baffles in up/downs, or filter sock holders, etc.)
To back up what James said, the 24x24x8 frag tank (which will likely see only about 7" of water) 1/2" rimless will do nicely. I've made several 36x24 rimless frag show/sale tanks with this height. 3/8" bows a bit too much for my tastes so that can't be used for constant use IMO, so I started using 1/2" which is not really that much more.
For the sump, if you want to do that rimless, I would go with 1/2" but again this depends on the baffle placement, height, and quality of construction method (i.e. are the baffles bonded in such a way they can be considered structural components). You could go with 3/8" if your baffles are structural and positioned to essentially divide the tank into smaller tanks, and your worst-case scenario water level doesn't present an overstress situation (that's all part of the planning). I have built many sumps using 3/8" but in most cases I try to add in a euro of some type, even if it's relatively small (like a 1.5" perimeter euro out of 1/4"). I also do 1/4" bottoms on most 3/8" sumps, unless the material useage means I can use a full sheet of 3/8". I use 3/8" baffles for "pressure" baffles, where there is a water level difference between each side, and 1/4" for separator baffles that have no water level differential (like the "up" baffles in up/downs, or filter sock holders, etc.)
Thank you..
Do you guys think if I push the tank to 48"x36" it will make a difference in the thickness to the acrylic. I figure when I laid it out it would not cost me any more to do that size tank in acrylic? it shouldn't since the size acrylic was based on the height and length of the longer panels. I just had extra acrylic.
James
I am trying to figure out how you came up with 720.00 for 1/2 or 1000.00 for 3/4 total cost. I drew it up on autocad last night and I figure at least 3 sheets. 3 sheets of 1/2" = 966.00 I think I really want to do 3/4" for the sides with bracing, I just feel better even though i know 1/2" is fine braced and saves money.
After the holidays I am going to pick up a piece of 1/2" for the frag tank and it also should be enough for most of the sump. See how it goes and then decide on if I can do a large tank. I am extremely handy but would hate to waste money on a tank and stand that does not hold water, a little scared. I just can get a much bigger tank this way than I could afford to buy or even get into my basement.. Tight fit trying to get anything in my basement. That 1s why I got rid of the 125 when I moved and the beautiful stand I just built.
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My mistake, I had read the 1/2" price incorrectly.. I read it as 240/sheet.. I'm still not used to how expensive it has become over the years..
48 x 36" only affects the 2 "ends" and with that - just increase the width of the perimeter flange on those sides a little. Or, if using 3/4" - no worries at all
I had failed to answer yesterday as to whether to perimeter flange ought to be routed out of one piece or "stripped" .. I will almost always opt for a solid piece on top. If a tank cracks, it's almost always originating in the top bracing and the simplest and best way to alleviate that is to use a good radius in the corners of the access openings. I know it takes a little bit more material but a relatively cheap and easy insurance policy in the long run.
James
My mistake, I had read the 1/2" price incorrectly.. I read it as 240/sheet.. I'm still not used to how expensive it has become over the years..
48 x 36" only affects the 2 "ends" and with that - just increase the width of the perimeter flange on those sides a little. Or, if using 3/4" - no worries at all
I had failed to answer yesterday as to whether to perimeter flange ought to be routed out of one piece or "stripped" .. I will almost always opt for a solid piece on top. If a tank cracks, it's almost always originating in the top bracing and the simplest and best way to alleviate that is to use a good radius in the corners of the access openings. I know it takes a little bit more material but a relatively cheap and easy insurance policy in the long run.
James
Have any pictures of your jig or how to route out those radius's in the corners. I was thinking one piece would be better but without the radius in the corners the corners it would be the first place to split. Found allot of out side corner jigs... I could always make a template for the router to follow maybe out of mdf but that seems like a big waste.
First, draw out the opening
My choice is to freehand the opening to get it close - you may not wish to do it this way
Tape your hole template in each of the corners and flush cut it
When you have your corners done, it'll look something like this
The basically connect the dots. You can do the whole thing on your finished piece, or use mdf/similar as template
Finished top. Personally, I bevel the top edges so there's nothing sharp
HTH,
James
I saw this photo and I think instead of a center brace doing a wide brace like in this picture.:
I hope this person does not mind me stealing the pic.
This would allow me to drill holes for plumbing in the bracing and would be easier to light.
See any issues? Any suggestion in width of bracing?
Also still debating on the side thickness... so many say 1/2" is plenty all the way around and actually doing the bottom and top in 1/2" and sides in 3/4" makes it harder to work with than doing just 1/2" sides..
I hope this person does not mind me stealing the pic.
This would allow me to drill holes for plumbing in the bracing and would be easier to light.
See any issues? Any suggestion in width of bracing?
Also still debating on the side thickness... so many say 1/2" is plenty all the way around and actually doing the bottom and top in 1/2" and sides in 3/4" makes it harder to work with than doing just 1/2" sides..
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