Acrylic fabrication questions? I can help!

[Floyd R Turbo]

Maybe go hybrid?

https://www.ntotank.com/325gallon-acerotomold-white-opentop-containment-tank-x8666939

I could use these tanks and create a rectangular interface box underneath: 3' x 4' x 1' high each. These would use three large 6" uniseals to connect up to the containers above, then 12 x 3" uniseals to the side.

More connections means more potential fault points but that could be a cheaper alternative?

So how would I build a rock solid low cost acrylic 36" x 48" box at 12" high? It needs to be able to carry 2600 lbs of tank and water above it...

That seems a bit better. Why would the tank have to sit on the acrylic box? Couldn't you place the tank on top of a couple of steel tubes?

The acrylic box under it would have to be overbuilt because it's going to be under the water column pressure above it, so you're talking a pretty beefy tank but since it's only 12" tall, that limits the bowing. I'm still not sure on the drain/fill/vaccuum thing, but I would think that would be at least better

 

[karimwassef]

I could use 2x6 studs and a plywood platform ... over more studs and a plywood platform for the boxes.... but wood is cheap. Until I have to cover it all with epoxy that is.

So.. how would you make those boxes? 3/4" double layers?

 

[Clowning_Around]

I have an acrylic question i need help with. I have built the majority of my diy sump out of glass but wanting to install the flat tray so to speak that has holes in it for socks out of a 1/2 piece of acrylic that I have. I feel this will give me some forgiveness with hole proximity and vibrations vs cracking of what would otherwise be a glass piece. Im not worried about the adhesion of silicone to the acrylic because it will be supported underneath by a ledge, so really it is just being water sealed. With that said it will be constantly submerged. I've heard acrylic swells and in some cases can expand such that it cracks adjacent glass if fitted between. In my application its only restricted in one direction. I was planning on leaving a 3/32 joint on both sides to allow for this expansion. So in total a gap of 3/16 which would be provided for my 6 inch piece in the same direction, is that enough gap? Ie how much should I expect a 6inch piece of 1/2in thick acrylic to expand by from water submersion? Also would it be ok to fill those gap joints with the compressible silicone? To play it safe, I can seal only the underside leaving the joints themselves open but access will be challenging, I would likely have to lay it in a bed of sealant which would most likely have some squeeze up into the joint. I hope all of that makes sense. Please let me know your thoughts.

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[Floyd R Turbo]

That's plenty of room for the acrylic to expand. Likely it would only expand a millimeter or less, so the silicone will compress, not a problem

 

[Clowning_Around]

thanks for the reply, i did some research while awaiting a response, based on my findings it will expand 1/32 total over the 6 inches.

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[JTL]

My plan is to purchase some 2" x 3/8" strips of polycarbonate to make a frame for an aquarium cover. I need to make a channel about 3/8" from the edge for the screen spline to fit into to hold the screen in place. I don't have a router but could I do this with a dremel tool? The channel needs to be 1/8 x 1/8. I also have a wet saw but the blade is only 1/16 and make two passes with precision would not be easy. Thoughts?

 

[Clowning_Around]

You can use a saw, just set a fence to use as a guide so ypu obtain your precision, any syraight edge with some clamps can do for a makeshift fence. A dremel, that would be more of a challenge for precision over long straight runs imo. Unless you clamp the dremel in a sudo router table application and feed your stock through it again using a fence as a guide for thr accuracy

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[JTL]

I have a dremel attachment the the tool screws into and you can set the depth. I could clamp a straight edge to the material and move the dremel along it. The there a a couple of dremel bits that might work and the are 1/8". I like the wet saw also, because the material may not melt and gum up the groove. Anyway a couple of options.

I am not going to get too fancy and planned on just using butt joints. They may not be as precise as I would like so I wonder if Weldon 4 is ok or should I try the thicker Weldon 16.

 

[Clowning_Around]

Actually a wet saw may gum up give the feed rate, try a test piece first acrylic generally doesnt like slow feed rates.

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[Clowning_Around]

If the cuts are to rough like tbl saw quality it will be hard to gey a quality seam with number 4.... you can try it and then follow with the 16 as a filler - food for thought

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[JTL]

Several of the cuts will be what ever they are from the fab shop (Tap Plastics). I figured I could sand them smooth. I think I read that WO 40 will not fix a poor fitting seam. Good thing is they don't have to be waterproof.

The dremel tool is sounding like my best bet.

 

[Floyd R Turbo]

Just so you are aware, polycarbonate is softer and tends to be "grabby". It's been recommended here (by James) that you are very careful, and whenever possible, use a template.

You might be better off laminating several pieces of acrylic together (or poly) to create the channel

 

[Terry6000]

Alright I got a question it's probably been answered before but I can't seem to find it. I'm building a tank with half inch cell cast I currently have all the walls of the tank welded together no bottom on yet. I noticed a small problem on the first seem I welded. Of course it's on the first seem. The problem is located at the edge of the seem (what will be the bottom of the tank. There is about 1/32 gap were the solvent didn't make it all the way down the edge and secondly there are 2 I would say good sized bubbles 1/4 from that gap. How should I go about filling the gap and bubbles? I was thinking about making a slurry with WO16 and some shavings and injecting it in. I have wo3,4,16 some very thin drills and 16 to 27 gage injecting needles. Or should I just weld a acrylic rod down that edge? It's going to be in a internal sump so to worried about the look.

 

[Clowning_Around]

Alright I got a question it's probably been answered before but I can't seem to find it. I'm building a tank with half inch cell cast I currently have all the walls of the tank welded together no bottom on yet. I noticed a small problem on the first seem I welded. Of course it's on the first seem. The problem is located at the edge of the seem (what will be the bottom of the tank. There is about 1/32 gap were the solvent didn't make it all the way down the edge and secondly there are 2 I would say good sized bubbles 1/4 from that gap. How should I go about filling the gap and bubbles? I was thinking about making a slurry with WO16 and some shavings and injecting it in. I have wo3,4,16 some very thin drills and 16 to 27 gage injecting needles. Or should I just weld a acrylic rod down that edge? It's going to be in a internal sump so to worried about the look.

If I where u and not worried about looks I would simply weld on a new small piece lengthwise over the seam (like a patch encapsulating the address in question)at the inside corner and move on. Others may have a better idea though....

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[Floyd R Turbo]

This is likely a result of air intrusion into the seam from the end. This is kind of typical actually, so some extent. While you can allow for overage along the joint so that a fillet can form and prevent air occlusion, you can't really do this on the ends where you will eventually bond the top and bottom on to the tank, unless you maybe place a piece of tape over that after you pull all the pins and allow the joint to initially set. But then you have to remove the tape residue before you can bond....

Upload a pic, this might help me confirm that this is what you are seeing.

But my gut tells me that once you put the bottom on (FYI put the top/euro on FIRST, the bottom goes on last) the solvent that you run for the bottom joint will wick up into the air gap you are seeing and it will disappear.

Also, the corners of a tank are the strongest points - you have 3 panes coming together at right angles (or at least, they should be at right angles) so this is the least of your worries.

If you are concerned about the integrity of the build when it is complete, then add a small gusset. You can use #3 or #4 or the equivalent for that, what you are wanting to do it reinforce the strength of the joint or rather distribute the stress across the gusset so that the bubble doesn't cause a weak spot. Taking the stress away reduces the problem, or removes it completely.

 

[Terry6000]

The best pic I could get doesn't really show the gap but you can see the bubbles. Pardon the red. I used bessy right angle clamps and the #4 wicked up the clamp. I'm still glad this is all in my sump.
I'm still on the fence about needing a brace. The tank is 16Hx12Wx92L inches. I want this to be braceless one places said 3/8 was enough the next said 5/8 thick what enough. I didn't have the money to go to 3/4 so I bought the 1/2. When I build the internal sump I plan on using a piece of 1/2 6-8 inches from the end I think this will help out the bad corner in question as well as a very little need for a brace. What do you think?

 

[Acrylics]

The best pic I could get doesn't really show the gap but you can see the bubbles. Pardon the red. I used bessy right angle clamps and the #4 wicked up the clamp. I'm still glad this is all in my sump.
I'm still on the fence about needing a brace. The tank is 16Hx12Wx92L inches. I want this to be braceless one places said 3/8 was enough the next said 5/8 thick what enough. I didn't have the money to go to 3/4 so I bought the 1/2. When I build the internal sump I plan on using a piece of 1/2 6-8 inches from the end I think this will help out the bad corner in question as well as a very little need for a brace. What do you think?

I wouldn't worry about the bubbles at all. Your top bracing will depend on how much other "stuff" is glued inside; baffles and whatnot. As a tank without baffles, it will definitely need a top brace; both a euro-brace at least one cross-brace. As a sump with baffles, etc., you'll want at least a euro-brace, cross-bracing dependent on other internals being glued in.

FWIW, at that size, even 1" would need at least the euro-brace.

HTH,
James

 

[Terry6000]

Ok so how thick does the brace need to be? The perimeter and center? Is it possible to just do a wide(12-18 inch) center brace. I hate the look of euro

 

[Terry6000]

Was my question that ridiculous or did I offend someone by saying I hate the look of euro bracing?

 

[Floyd R Turbo]

Nope, I know that I don't easily offend and James is pretty relaxed! It's understandable to dislike the look of a euro, but when it comes to structural integrity, it can sometimes be a necessity

As James mentioned, the need for a euro (and it's size) can depend on your baffles and how you build the sump.

When I build sumps, I install the end panels to the front just like when building a display tank, and then I also bond in the baffles at the same time. Then flip, bond everything to the back panel, then the euro, then the bottom. So all of those front/back/baffle joints are structural (versus if you were to add them in after it was made, and just wick in the solvent via capillary action - that's a weak bond and IMO not structural)

So if you have a lot of baffles, you can compensate for the lack of a euro.

Also, the operating water level matters, if it's going to be very full all the time (and you don't have much for power-off draw-down) then you will want it beefier. If you operate at a relatively low water level in the sump (relative to the height of the sump) then you might be OK with no bracing - but remember, the worst case scenario is when the sump fills all the way up. This is usually when there is an outage, so having the sump blow out then would be the worst time that could happen.

If you have a large section with no baffles, you can add in an intermediary baffle which would sort of look like a picture frame, or an "interior euro baffle" (oriented vertically)