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Discussion Starter · #1 ·
Hello, i originally was thinking about "ordering" steel stand, but i thought Plywood (Laminated Plywood) is pretty strong.
The playwood is 18mm (0.7inches) thick. It's made from 13 layers..
Stand will be L62xW42xH100Cm (25x17x40 Inches). Will it hold 190 Liters (50Gallons)? Safely?
The back is same playwood, connected from bottom, sides, middle, and top..
(Shelves will be removable, not screwed in)

Image of the stand:
 

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I don't see any major issues with your design, although I would recommend that you attach the vertical plywood elements to the back plate every so often either by nailing through the back, or with 90 degree clips on the inside. This helps brace the vertical elements from buckling under the weight which would be the biggest concern for failure with this type of design.
 

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I don't see any major issues with your design, although I would recommend that you attach the vertical plywood elements to the back plate every so often either by nailing through the back, or with 90 degree clips on the inside. This helps brace the vertical elements from buckling under the weight which would be the biggest concern for failure with this type of design.

You mean to prevent racking?
Yea the left and right shifting always bothers me in this type of build, especially w/ all loose shelves.
Nailing th verticals though the plys isn't very structurally sound.
Brackets are better.


When I built cabinets like this commercially we actually used silicone and some screws/nails. I was told the screws were mostly to hold the panel in place till the silicone cured. Granted these were mostly particle/mdf and melamine coated panels.



Others may agree or disagree but the back should be construction adhesive-d (or siliconed) to all vertical members and some nails/screws.
Trick to not get too long of screws or using nailers not to get some ruining your plywood..;)
Then again can't think of anything I personally built that probably wasn't probably 5x strength necessary..


One of the reasons anytime I even THINK of building a stand I go right to dimensional lumber EVEN knowing in some cases plywood could be better.

Of course things like wood outside corner strips adds a bit of a more finished look and can be structural as well.
 

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Others may agree or disagree but the back should be construction adhesive-d (or siliconed) to all vertical members and some nails/screws.
I would definitely do this. With plywood there is little to no wood movement and thus zero reason not to use an adhesive. Normally I would use wood glue for this but this is going to be a coated plywood? Depending on what it's coated with I would use an appropriate adhesive for that coating and the more porous edges of the plywood it will be connected to. A proper adhesive will be significantly stronger then screws/nails or other mechanical fastening. I would also find a way to protect the exposed edges in front (assuming you are building this thing yourself). Something as simple as paint can work or you can edge band it.
 

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Discussion Starter · #5 · (Edited)
Isn't the coating on plywood just for look? Will glue/silicone/liquid nails.. Hold on it?
(Ok it will hold on the coating of playwood, BUT will the coating it self hold on playwood so good?)
Yeah i was tinking of using some kind glue..

How much weight could this stand hold in general?
I'm little bit worried that the wood will break or bend little bit causing the tank to crack xD

Maybe i will add some "L" brackets 2 large ones each conner? Like this or should i add some also to back wall?
 

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You mean to prevent racking?
Yea the left and right shifting always bothers me in this type of build, especially w/ all loose shelves.
Nailing th verticals though the plys isn't very structurally sound.
Brackets are better.


When I built cabinets like this commercially we actually used silicone and some screws/nails. I was told the screws were mostly to hold the panel in place till the silicone cured. Granted these were mostly particle/mdf and melamine coated panels.



Others may agree or disagree but the back should be construction adhesive-d (or siliconed) to all vertical members and some nails/screws.
Trick to not get too long of screws or using nailers not to get some ruining your plywood..;)
Then again can't think of anything I personally built that probably wasn't probably 5x strength necessary..


One of the reasons anytime I even THINK of building a stand I go right to dimensional lumber EVEN knowing in some cases plywood could be better.

Of course things like wood outside corner strips adds a bit of a more finished look and can be structural as well.
No racking wasn't what I was getting at. If you attach the back panel to the top and bottom panels, you won't get racking of any sort, even if you don't attach it to the vertical members. The back panel braces the whole lateral movement potential of the system.

The issue I was talking about was the vertical members buckling



With thinner vertical members like plywood sheets, you run into this potentially happening. To prevent buckling, you just need to brace the vertical members every so often so that they can't bend out of plane like shown in the picture. This can be done with bracket clips or by nailing directly through the back board. I would agree that the brackets would likely be the easier and more effective of the two solutions.

As for fasteners, I would definitely go with nails/screws over silicone. If you want to use an adhesive, you're much better off going with an industrial wood glue. Cabinets typically aren't rated for 300+ lb loads so I would be much more hesitant to use lighter adhesives like silicone.

Isn't the coating on plywood just for look? Will glue/silicone/liquid nails.. Hold on it?
(Ok it will hold on the coating of playwood, BUT will the coating it self hold on playwood so good?)
Yeah i was tinking of using some kind glue..

How much weight could this stand hold in general?
I'm little bit worried that the wood will break or bend little bit causing the tank to crack xD

Maybe i will add some "L" brackets 2 large ones each conner? Like this or should i add some also to back wall?
Adding the brackets in the locations that you have won't really add much, because you already get that stability by fastening the back panel to the vertical and top and bottom members.
 

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Orig drawing shows the back on top/bottom of the bottom/top. One could also make one shelf perminent. Say the middle one on each. One can then discuss the best way to do this 🙂

As to "my" cabinets, like I said these were commercial grade not Ikea ..

Silicone was used because melamine is non porus

https://www.homedepot.com/b/Paint-P...tion-Adhesive/Waterproof/N-5yc1vZci1oZ1z17g2x

https://chemicalwiki.com/best-silicone-sealant/

Melamine adhesive https://www.woodworkingtalk.com/showthread.php?t=5306


Re current thoughts on melamine.
Laminates are mostly paper below, melamine top.
 

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Discussion Starter · #8 ·
Redid stand lil bit..
Now it's all screwed together. Second playwood to hide screws, and screws will be under shelves from one, then other side vise versa.(Yellow things)
Doubt there will be any racking now xD
 

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Compressive strength of plywood is pretty good. Similar or better then real wood. Your biggest issue is if it gets compromised (in this case wet and starts to delaminate). If your tank weighed several times its expected weight it would still be fine under the original drawing and also under the second. I would again emphasize racking being your biggest weakness. A fish tank is a live weight and will shift its weight over time.

Which adhesive you use depends entirely on what the plywood is coated in. There are different adhesives for use with things like melamine vs other options. I frankly would be tempted to use a regular piece of ply with the back so you can use a regular wood glue.
 

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Discussion Starter · #10 ·
Compressive strength of plywood is pretty good. Similar or better then real wood. Your biggest issue is if it gets compromised (in this case wet and starts to delaminate). If your tank weighed several times its expected weight it would still be fine under the original drawing and also under the second. I would again emphasize racking being your biggest weakness. A fish tank is a live weight and will shift its weight over time.

Which adhesive you use depends entirely on what the plywood is coated in. There are different adhesives for use with things like melamine vs other options. I frankly would be tempted to use a regular piece of ply with the back so you can use a regular wood glue.
How can it rack? If it's all bolted, glued together (All sides+both sides of shelves)
I could use regular playwood, then tint it and after that some floor matted lacquer (to make waterproof)
 

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Discussion Starter · #11 ·
Quick question, how thin plywood could i go, if i wanted? For second design? (All shelves, everything glued, screwed together)
 

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The over builder in me ( i reinforced my stock melamine cabinet) would go with 3/7" plywood. The wood worker it me would either use tite bond III ( it's waterproof) or pl premium construction adhevise ( again that's way over doing it).

Be warned if you use pl premium and you want to stain your shelves you have the wipe off the excess quickly and thouroughly or you won't get good results with your stain. Don't ask me how I know!!!!

r
 

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Discussion Starter · #14 ·
I will use waterproof glue.(My contry have different glue types, thinking of ussing on water base, that you can wash off fast..)
After that i will add some black tint in see true water base lacquer. (Will be blackish and waterproof) In one go.
(Will test results on some leftover plywood first doh xD)
 

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Since joining plywood at the edge is somewhat suspect for fasteners as they tend to go in between the plys and may not get a good grip. I certainly go with glue but to make a much easier and stronger joint. I like to add a strip of wood at the inside corner which is glued in with good wood glue as plywood is very good for letting the glue soak in and make the joint stronger than the plywood itself. Something as small as a 3/4" angle of solid wood is quite easy to fit in and glue to both back and sides.
Rather than use double wood in the center and break up the larger storage space into two that may be too small, I would add a horizontal at somewhere near the middle of the front to act to keep the vertical from bowing.
Any thoughts to where one might put a canister filter or CO2 at some future date?
 

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Your design structure with 18mm plywood should be fine. My cabinet (90cm x 45cm x 80cm) for my 180 L aquarium were built with only one vertical structure in the middle and it's strong. It's made in a furniture workshop.
 

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