# Plywood Terrarium Construction



## hydrophyte (Jun 5, 2009)

*Plywood Terrarium Construction*

I'm working on a new medium-large setup that I have been discussing over in this other thread... http://www.dendroboard.com/forum/members-frogs-vivariums/80143-paleo-viv-concept-thread-12.html

I have a few questions about the plywood construction. I have already cut out the panels with the dimensions shown here...









I still need to make the cutouts for the viewing panels and the top. This drawing shows the cutouts with frames 3.75" on both sides of the viewing panels and all around the top opening. The frame at top edge of the viewing panel is 3". With the .75" plywood thickness there will be 3" of margin on the inside. Will this be strong enough?

I hope that skanderson or somebody else can consider my second question. I was planning to get the epoxy from US Composites. Can you recommend which resin product to use? Can I tint this epoxy with black iron oxide? I have a 5 lb. bag of iron oxide here and it would be nice to use some of it up. How about the fiberglass?


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## hydrophyte (Jun 5, 2009)

Tomorrow I am routing the cutouts with the CNC panel router (a lot easier than using a circular saw) and the panels will be ready to screw together with 2" wood screws.

I have heard that for the most secure seal you should apply epoxy to every joint as you assemble the panels. This will be messy and I wondered about instead using a construction adhesive--I also read about this as a suggestion--or silicone(?). Any opinions about this?


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## Bighurt (Jun 18, 2011)

Using epoxy between the joints is your best bet.

I would stick with a 635 or west systems 105.

Unless you want to build a fillet in the corners, both will be fine over ply. The epoxy can be tinted with powdered pigments, acrylic paste, or graphite powder.


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## dsaundry (Sep 29, 2011)

Curious, what was your motivation to use plywood for your build and not glass or acrylic?


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## Bighurt (Jun 18, 2011)

dsaundry said:


> Curious, what was your motivation to use plywood for your build and not glass or acrylic?


Mines cost.

Glass $11 a sq foot.
Plywood $2.84 a sq foot, including epoxy.

Paying for something I'll never see and don't need, worthless.


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## hydrophyte (Jun 5, 2009)

Bighurt said:


> Using epoxy between the joints is your best bet.
> 
> I would stick with a 635 or west systems 105.
> 
> Unless you want to build a fillet in the corners, both will be fine over ply. The epoxy can be tinted with powdered pigments, acrylic paste, or graphite powder.


Thanks. I'll just use the eopxy in the joints. I was thinking about mixing epoxy one less time and I also wanted to avoid mucking up the plywood on the side panels with epoxy squeezing out. Now I think I will just prime and paint all of the outside surfaces instead of trying to finish the natural wood, so that won't matter much. 



dsaundry said:


> Curious, what was your motivation to use plywood for your build and not glass or acrylic?


I think that this enclosure would be too big for me to build very well with glass. It is going to have about 165 gallons of volume. I could have considered using 1/4" plate glass, but I think it wouldn't be strong enough and 3/8" plate would have cost me an arm and a leg. I have to be able to get this thing up and down the narrow basement stairway in our old house and plywood will also be lighter. 

Acrylic is no good. It warps badly in the presence of warmth + humidity and it scratches so easily.


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## jglow84 (Apr 5, 2013)

Us composites is a great source for epoxy and their thinset 635 formula works great, is tintable, and brushes on well.


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## hydrophyte (Jun 5, 2009)

I ordered the 635 thinset. I hope to see it here pretty soon.

I used the CNC panel router at our local hackerspace shop for the viewing panel cutouts. I was just going to use my circular saw, but they convinced me to use the panel router instead. This surely saved me a lot of time sanding straight the uneven cuts that I would have made with the circular saw.


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## jglow84 (Apr 5, 2013)

sweet build. shop bots are frickin awesome....as long as you can use sketchup...

question: and sorry if this is a hijack, do you think you could use wood for just the bottom, back and top, in order to leave three glass panels for viewing but without a frame on the front edges? I like your point about not paying for something you wont ever be able to through anyway.

Also good luck with the epoxy. If you are going to use epoxy in the joints as glue you may want to consider the additive us composites sells to make the 635 a thicker consistency, or if you have the clamping ability, titebond 3 is about the strongest glue, is fairly waterproof once it cures and you can easily epoxy over it. but clamping is super important with tb 3. also pocket screws with a krieg jig might be a decent idea to use in addition to whatever glue you use


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## hydrophyte (Jun 5, 2009)

The router was a lot easier than the circular saw would have been. You just have to stand there and watch it slowly make the cut in several passes. They have all of the software over there for us to use. 

If you used the right kind of construction you could use glass around three sides and make the other panels with plywood. I think I saw an enclosure like that here on dendroboard somewhere.

I was planning to put it all together first with half of the screws, and then disassemble a couple of corners at a time to brush the epoxy into the joints before fastening with all of the screws. Do I really to clamp if I am also using lots of wood screws? Do you really think pocket screws are necessary? I was going to put a 2.5" wood screw in every 4".


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## jglow84 (Apr 5, 2013)

couple of things before i give you bad advice.

1. Clamping only applies with wood glue. epoxy only needs moderate pressure or you will squeeze out the epoxy. screws will work fine.

2. pocket screws arent stronger or special, just a way to hide the screws and/or drill from the inside of a 90 degree joint.

3. if you are drilling into the side of plywood, i would predrill all my holes. 

hope this helps.


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## hydrophyte (Jun 5, 2009)

I don't need to hide the screw holes at all. All of the outside panels are going to be painted. I am just going countersink and fill the screw holes with wood putty. 

I think that the screws will be strong enough. I'm using a lot of wood screws.


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## Bighurt (Jun 18, 2011)

I would wet out the joint first as one typically does in the two stage epoxy joint. Apply your epoxy without additive to both sides of the joint ensuring full coverage.

Then apply a second thickened mixture anytime before the wet-out coat has cured.

The second application can contain fillers to bridge gaps in the joint, but at least enough to thicken the application so you don't end up with a resin starved joint.

The joint should be clamped.

Screws, brads and traditional clamps will work while the epoxy is curing. The process can be messy and I like my clamps so I'm a screw/brad nail fan. And this is a vivarium...

Remove any excess immediately or your finish will be effected.

For additional information see the how to guides on west systems site.

Cheers


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## hydrophyte (Jun 5, 2009)

Bighurt said:


> I would wet out the joint first as one typically does in the two stage epoxy joint. Apply your epoxy without additive to both sides of the joint ensuring full coverage.
> 
> Then apply a second thickened mixture anytime before the wet-out coat has cured.
> 
> ...


Thanks so much for this complete explanation!

I have a question about glass. Do you think I can get away with using 1/8" "strong" window glazing? It costs 1/2 as much as 1/4" plate and it will also be much lighter. I suppose the main hazard would be that it would break more easily if it got a hard tap.


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## Pumilo (Sep 4, 2010)

hydrophyte said:


> I have a question about glass. Do you think I can get away with using 1/8" "strong" window glazing? It costs 1/2 as much as 1/4" plate and it will also be much lighter. I suppose the main hazard would be that it would break more easily if it got a hard tap.


If I am following correctly, you will have glass panels as large as about 48" x 35.5 inches (allowing 1/2" inch for overlap to mount it). I would not be comfortable with that size glass in only DS (approx 1/8"), even if "toughened" or even tempered. "Strong" is not really a proper term in the glass industry, but might be used to describe tempered or toughened.

The 40" x 24" side panels? Hmm, maybe. I am *not* recommending it professionally, but I just might do 1/8" tempered for those smaller side panels and the top. 
(except for the fact I could get in 1/4" for free, as salvage scrap from my glass supplier, so I would actually go full on 1/4")

One thing you can keep in mind is that glass is much stronger when the edges are protected, as they will be in your build. I can take a hammer and whack a glass unit harder than you would think I could, as long as I hit it on the *flat*. If I barely tap it on the *edge*, it can crack quite easily.


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## hydrophyte (Jun 5, 2009)

Thanks. With the 3 1/2" plywood frame around the sides and top and a 1/2" overlap, the two larger pieces of glass for the side panels will be 41" X 26". This is pretty big. I probably should just get the 1/4" plate, but it will cost me almost $200 for all of it. I have chipped a couple of fish tanks along the edges, but I've never run an object right through the middle of a glass panel. I suppose there's a first time for everything. LOL.

I got some pieces of "strong" once before and the people at the shop explained that it is a full 1/8" thick. Regular window glazing it more like 3/32". I understood that the strong is not tempered or hardened, but the extra thickness makes it substantially stronger. It is recommended for doors.


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## Pumilo (Sep 4, 2010)

hydrophyte said:


> I got some pieces of "strong" once before and the people at the shop explained that it is a full 1/8" thick. Regular window glazing it more like 3/32". I understood that the strong is not tempered or hardened, but the extra thickness makes it substantially stronger. It is recommended for doors.


I'm very sorry to have to disagree with you on this, but the people you talked to "at the shop" are very wrong, at least on their extremely poor knowledge of doors and tempering laws. 
Federal and international building code laws all require tempered glass to be used in all doors. If you use non-tempered glass in any door, anywhere, and somebody gets hurt, it is a slam dunk law suit.
Their knowledge must therefore be completely questioned. I have a professional, working knowledge of glass, and I have never heard of "strong" glass as a terminology in the field. None of my suppliers offer anything called "strong" glass. If you google "strong glass", it should become obvious fairly quickly that this is simply a term that your glass shop made up.
I don't know if they are a glass shop, a hardware store, or what, but they have little working knowledge of glass, and you should question what they tell you and sell you.


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## hydrophyte (Jun 5, 2009)

Thanks also for this explanation. I won't go back to that shop again.

I'm just gonna use the plate glass for this project. I might be able to find some kind of scrap for the top to save a few bucks.

Have you ever worked with thinner tempered glass? Is it more difficult and costly for a shop to cut such glass? How does the cost compare with 1/4" plate glass? I have other projects in mind and I am interested to know more specifics.


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## Bighurt (Jun 18, 2011)

I'll bow to Doug on the glass piece since he is in the trade.

However I will say when I kept large boids I had both tempered and safety glass bypass doors. As Doug said Glass doesn't like edge contact of any kind and this goes for both plate and tempered. 

However Safety glass is unique and is stronger. I had a large boid pop the glass on her enclosure, third from the bottom. About 48" off the concrete floor. 

I found the glass intact and the animal still in the cage, scared the crap out of me cause I found it after dark.

Never the less the glass impacted on a corner, chipped the concrete. Only a minor chip on the glass edge. I prefer safety glass on all boid enclosures after that incident. In reptile keeping its a rare event to keep spare doors, I'm glad I didn't have to move her that night.


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## Pumilo (Sep 4, 2010)

Hey Jeremy, what exactly do you mean by "safety glass"? It is a term used in the industry, but it is generic. It can refer to tempered glass, toughened glass (which is partially tempered, sometimes called hardened), laminated glass, laminated with wire reinforcement, or any combinations of those. 
I am doubting the use of laminate glass in vivs. I have never heard of it being used. Obviously wire mesh reinforcement is not used. Therefore my best guess, since you said it took a chip like a pro, is that it is NOT tempered, but perhaps toughened. Standard, annealed glass could also survive a chip easier than tempered.

Finally, tempered glass is odd. It would be rare, but tempered glass _could_ survive a hefty chip, or incredibly rarely, even survive being drilled, only to "explode" into a thousand tiny pieces, hours, weeks, even years later for seemingly no further reason. It has to do with interrupting the surface tension. If you want to get sciencey (why isn't that a word?), here is a pretty decent explanation How is tempered glass made? - Scientific American. 

Sorry for the sidetrack.


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## Pumilo (Sep 4, 2010)

hydrophyte said:


> I'm just gonna use the plate glass for this project. I might be able to find some kind of scrap for the top to save a few bucks.


Love me some good scrap. I've built a lot of vivs out of scrap glass that would otherwise be in the landfill.



hydrophyte said:


> Have you ever worked with thinner tempered glass? Is it more difficult and costly for a shop to cut such glass? How does the cost compare with 1/4" plate glass? I have other projects in mind and I am interested to know more specifics.


You don't work with tempered glass. It cannot be worked with. They first take normal, annealed glass. They cut it into the shape you request. Any holes must be done before tempering. The edges have to be sanded to remove any imperfections. A tiny ding could cause the entire pane to "explode" during the tempering process. Finally it is heated and flash cooled. It can never be worked or formed again. (Actually I've heard there is an anti tempering process that is very expensive, and pretty much worthless)
As far as pricing, every company is different. I found I had to add in about 35% onto the price of an insulated glass unit to cover the tempering process. Not too bad for something that, no matter how much I love DIY, you simply cannot recreate yourself at home, or in a small to modest shop. Price it around. Prices can vary quite a bit locally.


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## Bighurt (Jun 18, 2011)

Pumilo said:


> Hey Jeremy, what exactly do you mean by "safety glass"?


Laminated glass


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## hydrophyte (Jun 5, 2009)

I ran into this interesting article series on a boatbuilding site...

Shop Tips » Working With Epoxy and Fiberglass


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