Mountains of sawdust (360g plywood, LED, Arduino build)

Everytime I check in on you this gets more and more impressive. I see that you referenced MattShacks build, do you know if he has updated in a while? Thanks for sharing what you are doing.
 
Haven't seen Matt's thread in a little while.

More slow progress:

Using the plugs from the holes to pour epoxy was a good idea. I got a perfect-sized hole. Using painters tape was a bad idea in this case. When using the painter's tape to mask off the panels I was pouring earlier, the sticky side of the tape was facing the epoxy and it peeled off easily. When I taped up the plugs, the plain side of the tape was facing the epoxy, and it STUCK GOOD to the epoxy. :( All was not lost though, I hammered the plugs out and the tank is fine, but there is tape embedded in the epoxy in the holes, so I'll have to sand it out.

Also, I started pouring the fillets in the corners of the tank:

IMG00111-20100205-2049.jpg


Each fillet is around 3/4", and I'm pouring them in one layer. This is very easy, takes only a few ounces of epoxy, and should be just as strong as using wood 45's in the corners.

I was originally planning on building little jigs to hold the stand at 45 degrees to pour the corners, but I remembered the 90 degree clamping jigs I made to assemble the tank, so I used those to prop the tank up:

IMG00110-20100205-2049.jpg


I can clamp them to the workbench and reposition them to hold the tank solidly at 45 degrees for each fillet. It's quick and easy and holds the thing very securely (the post in the middle was just to help keep the tank even while I clamped the jigs down, I removed it later - it's not bearing weight).

Here's a finished fillet:

IMG00111-20100205-2049.jpg


That's along the bottom of the front viewing panel. You can kinda see how thick the epoxy is around that opening, too.

Also, I started thinking/planning in more detail about actually putting this thing in the house. On Saturday, I mocked up the tank and the wall that will enclose it:

IMG00112-20100206-1019.jpg


My wife would kill me for posting a "messy" photo of our house, but you get the idea. The chairs and toys to the left are sitting in what will become the short hallway along the "end" of the tank. The narrow strips of duct tape on the sheet itself show the position of the front viewing panel, and the bench shows the position of a built-in bench that will be under the front viewing panel, serving three purposes: allowing me to get in the tank for maintenance (by standing on it), allowing the kids to see in to the tank (again, standing on it), and acting as toy storage for the kids (the top will be hinged). Finally, the bins of toys near the end of the sheet show the width of the tank. Unfortunately, it's hard to stand back far enough to get a good perspective on how the finished product will look, but mocking it up like this for a weekend let us get a sense of how it will alter traffic flow and regular household activities.

For reference, here's a 5' 125 I had in the same position:

IMGA0160.jpg


I can "age" that picture by noticing all the differences between it and the mock-up shot above. :lol:
 
More or less:

1) Used 120 grit sandpaper to rough the epoxy. Then vacuumed the dust out, then wiped down with a damp paper towel, and let dry. I did this for all joints at once so I didn't have to keep breaking out the vacuum.
2) Propped the tank up at 45 degrees for a particular joint
3) Mixed a few ounces of epoxy. The 6' joints are getting 6 ounces; the smaller joints will get 3 (it's hard to mix in amounts not divisible by 3 because of the 2:1 ratio and one-ounce metering pumps I'm using, but these amounts are pretty close to what I want anyways.)
4) Poured the epoxy evenly along the joint.
5) Ran a plastic spoon up and down the joint a few times. This helped even the epoxy out, evacuate air bubbles, and it also wet the epoxy a littler further up each side than it naturally would have (surface tension), forming a slightly smoother transition.

It's easier than it sounds. I've done two of the joints so far and it probably takes 4 or 5 minutes each - just have to let the epoxy cure before I move on to the next joint.

I thought about thickening the epoxy to a paste consistency and forming the joints by troweling them in like you would on typical composite construction, but this is less work (it settles into a perfect fillet, no need to tool it to that shape), and the few ounces of weight difference won't be an issue here. The one advantage of going that route would have been that I could have done all the seams at once, but again that's not really an advantage here.
 
Oh, and a few more photos from "reliability experiments."

I mentioned above that I had to hammer the plugs out of the holes. Well, one of them was REALLY tight - it wasn't held in place due to the epoxy acting as an adhesive, it was just REALLY tight in the hole. I had to wail on it with a 5 lb mallet to get it out. I was hammering on the face of the plug that had been epoxied (from before the hole was cut). When it finally came out, it exploded apart. It was pretty cool to see the damage. The 3/4" of plywood was totally sheared apart, but the 1/8" thick disk of epoxy - which was taking the brunt of the force - was in one piece, relatively unharmed. In fact, it was the wood that broke; the epoxy still had a ply or two stuck to it:

IMG00116-20100208-1419.jpg


Also, I had mentioned earlier in the thread that I was a little worried about adhesive and epoxy penetrating through the oak veneer on the face of the plywood. I had some scrap that had voids directly under the oak veneer, which provided good opportunity to test. These voids are around 1/16" wide. I taped up the end of one of those scraps and filled the void with epoxy. Sure enough, the epoxy bled right through to the exposed face of the veneer, so penetration was pretty good. But I wanted to see how good, so I rigged another test. I taped up the void on another short piece of plywood, poured epoxy in it, and then just laid it on top of another piece of scrap. The epoxy bled through the veneer significantly enough to glue the two pieces together. I separated the two pieces by hammering on them. The veneer ripped off the sample for a few inches on either side of the void! The epoxy bled through enough to create a bond stronger than the wood, for an inch or two on either side of the void:

IMG00115-20100208-1306.jpg
 
More progress, but no photos.

As far as the tank itself, I am DONE with epoxy! YAY! Spent a few days this week pouring the corners, filling and smoothing screw holes, another coat on the eurobrace, etc. On Monday I'm painting the exterior of the tank, then final sanding and touchup, then glass.

And, I started the first major project besides the stand itself - working on the support for the stand. It's kind of refreshing to be doing something besides working on the tank for a change. And it's exciting to "break ground" in the house itself.

This house is very old - nearly 200 years - but it's been stripped to the frame and remodeled at least once. However, the basement and frame are still original. The basement is partiall dirt floor with a dry fit stone foundation. The frame is post and beam. It's a really neat history lesson in home building. Luckily, one of the main beams in the house runs directly below the tank - it's about 16" square (no, I am not making that up. :D ). However, it has mortises cut into one side to fit other beams, and considering the age, I don't totally trust it. About 2' away is another smaller parallel beam. Those two beams will support the tank. These beams span around 14' and the tank is situated such that the overflow end is about 2" from one end of the beams. So the other end of the tank is out near the middle of the beams, unsupported.

To support them, I screwed a 4x4 to the bottom of each, about 3' long. This is just for weight distribution. Under each 4x4 beam I added a 4x4 post. The posts are resting on 50 lb pier blocks, set in 18" square concrete pads.

I also screwed a 2x6 between the beams to lock them together, though I really doubt a 200 year old beam as big as these would warp all of a sudden. :D

I'll try to get pics but it's dark and nasty down there so it'll be tough. . .
 
Nope. There won't be any UV. (Hooray for LEDs!) And at any rate, the bottom of the tank will be covered by sand and the sides will be shaded thanks to the big opaque eurobrace. So none of the epoxy interior will be exposed, really. And, FWIW, many people that do paint the interior of their tanks use sweetwater epoxy paint - the label on the can warns that it'll get chalky when exposed to UV, so it's probably not a good choice anyways.

The outside of the tank will be mostly covered once it's installed, but I'm painting it with high-grade exterior enamel with a lifetime warranty. It was reasonably priced (like $30/gallon) and should do just fine for protection from the occasional drip or salt spray.
 
I tried, but the camera broke. :lol:

I was sitting inside the tank, touching up a few spots on the eurobrace with epoxy. I leaned over to look at one of the holes for the closed loop and leaned my head right against the eurobrace. Didn't realize it until a couple minutes later when I did one of those "scratch your head and think" moves and felt something wet in my hair. :eek:
 
wow, what a build. Ive been nervous on building with wood because I heard they lack strenght compared to glass, like in the seams etc. After reading your progress it sounds like as we advance in wooden builds, its almost the oposite. what are your thoughts? Oh and BTW, im subscribed lol.
 
wow, what a build. Ive been nervous on building with wood because I heard they lack strenght compared to glass, like in the seams etc. After reading your progress it sounds like as we advance in wooden builds, its almost the oposite. what are your thoughts? Oh and BTW, im subscribed lol.

With any material, the approach and technique is important. There are plenty of failure stories for wood tanks out there. However, there are also lots of failed glass and acrylic builds. All three methods are totally viable if done correctly. Some of the folks I consulted with before choosing wood have had tanks much larger than this running for years without issues. If anything, my tank is a bit on the "wimpy" side for a "modern" wood approach, but I'm still very confident that it'll be fine.

Wood definitely takes more time/effort than glass or acrylic. But to me, it's enjoyable work, so that's a benefit, not a drawback.

Wood is definitely cheaper than a commercially built tank in this size range. Comparing DIY to DIY it's probably somewhat of a wash depending on material choices, etc.
 
Ladies and Gentlemen, I present the large white box:

IMG00122-20100217-1321.jpg


Epoxied, sanded, filled, smoothed, epoxied some more, sanded, filled, and finally - painted on the outside. All that really remains is some touchup work and glass.
 
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