Shimming Aquarium Stand Top

[jeebsbyreef]

I’m making a 36x21x36 stand for my 65 gallon rimless tank. I’m trying to make it good enough, but I’ve never done woodworking so I’m pretty new to this.

I made the frame based on Rocket Engineer’s design, but the top (or, if I turned it over, the bottom) is uneven. I’ve attached pictures here to show what I mean.

Would adding shims as shown in the pictures be acceptable? Or should I just start over and try to make the frame more level? The gap at the widest is going just over 3/8”.

 

[DaddyFish]

The gap you show in the very last picture is my #1 concern. The vertical uprights absolutely, positively must rest solidly on the horizontal frame boxes. That's a structural requirement. Right now your upright with the gap at the end is held in place only with the strength of the screws. That won't work.

If your frame is 3/8" off and you're certain the floor it's sitting on isn't the out-of-level problem, then I'd say start over and trim your uprights until they are all eight the exact same length.

Adding...
It looks like you may not understand the principle design?
The uprights should span across the joints of the horizontal boxes, not directly inline.

On a small stand like this you only need four uprights of exact length. You certainly can make an L-shape upright by screwing two together. But in my experience the inner pieces that hold it all together for assembly are well worth the effort. So I use three(3) 2x4s in each corner, not two.

Sorry, I'm colorblind so I suck at pointing out the components by color!!!
I believe the uprights are purple??? Those eight(8) pieces need to be exactly the same length and sit firmly between the two horizontal "boxes".

 

[JumboShrimp]

Those plastic shims can probably hold an elephant, so I was going to say, 'Shim the heck out of it--full speed ahead," but I am far from an engineer and I would hate to be responsible for a tank-failure on someone else's tank. I will definitely defer to @DaddyFish ... who actually sounds like he knows what he's talking about!

 

[DaddyFish]

Those plastic shims can probably hold an elephant, so I was going to say, 'Shim the heck out of it--full speed ahead," but I am far from an engineer and I would hate to be responsible for a tank-failure on someone else's tank. I will definitely defer to @DaddyFish ... who actually sounds like he knows what he's talking about!

It's all good. I tend to be overly cautious, but I do believe the OP will wind up putting more effort into shimming it properly and dealing with the gaps, than would be required to take it apart and true it up.

 

[JumboShrimp]

(You could be right there... what's backing out a few screws between friends? Hee, Hee, Hee.)

 

[Jedi1199]

I agree with DaddyFish. I personally would not shim under the top itself. I would attach the top tightly to the framing members and then shim from between the stand and the floor if needed. After, of course, fixing the problem that is causing the top to not sit true in the first place.

Better to put in the work now than clean up the mess later...

 

[DaddyFish]

@jeebsbyreef Here's a tip for you...

Many people get into trouble building stands by assuming the concrete floor they are using is actually level.

Shim your bottom frame box until it's level. Make sure your shim material protrudes well into the corner so it keeps the inner vertical tie-in pieces spaced up as well. You don't want them to protrude below the bottom edge of the lower frame box.

Then set the four corner "units" in place, sitting firmly on the bottom frame box. Run one screw from each inner vertical piece (the one that's for assembly purposes) into the bottom frame box.

Next add your top frame box and press it down firmly at each corner as you add one screw from the inner vertical.

Now check your level across the top. Assuming your verticals were cut to exactly the same length, It should be just as "true" as the bottom frame was.

Finally you can add your top plate and the rest of the screws. Don't overdo the screw count. The screws only hold everything in place for transport and basic lateral stability. The weight of the tank and water is supported by the union of the top/bottom frame boxes and eight vertical spacer posts.

 

[jeebsbyreef]

Thank you all for your help!

Adding...
It looks like you may not understand the principle design?
The uprights should span across the joints of the horizontal boxes, not directly inline.

On a small stand like this you only need four uprights of exact length. You certainly can make an L-shape upright by screwing two together. But in my experience the inner pieces that hold it all together for assembly are well worth the effort. So I use three(3) 2x4s in each corner, not two.

Sorry, I'm colorblind so I suck at pointing out the components by color!!!
I believe the uprights are purple??? Those eight(8) pieces need to be exactly the same length and sit firmly between the two horizontal "boxes".

@DaddyFish Don’t worry, I’m colorblind too, so I get what you mean by purple haha. What do you mean the uprights should span the joint of the horizontal box? Comparing my attempt to the picture you posted, I’m having trouble understanding the difference. Can you explain a little more?

Many people get into trouble building stands by assuming the concrete floor they are using is actually level.

Shim your bottom frame box until it's level. Make sure your shim material protrudes well into the corner so it keeps the inner vertical tie-in pieces spaced up as well. You don't want them to protrude below the bottom edge of the lower frame box.

Then set the four corner "units" in place, sitting firmly on the bottom frame box. Run one screw from each inner vertical piece (the one that's for assembly purposes) into the bottom frame box.

Next add your top frame box and press it down firmly at each corner as you add one screw from the inner vertical.

Now check your level across the top. Assuming your verticals were cut to exactly the same length, It should be just as "true" as the bottom frame was.

Finally you can add your top plate and the rest of the screws. Don't overdo the screw count. The screws only hold everything in place for transport and basic lateral stability. The weight of the tank and water is supported by the union of the top/bottom frame boxes and eight vertical spacer posts.

To make sure I understand correctly, you're saying to take the following steps:

1. Build the bottom frame box (how can I make sure this is level if the wood is curved? One issue I had was, even though I had a flat work bench, the frame boxes were still wobbly after everything was put together, either on one side, the other side, or both.)
2. Shim the bottom of the bottom frame box to make sure it's level.
3. Attach the corner pieces (assuming these pieces should already be assembled, as in I should have four sets of three 2x4 vertical supports, each with an inner vertical and two verticals that are the actual supports?).
4. Add the top box frame. If the 2x4's are good enough, this should be level as is.
6. Add the rest of the screws. Is 3 per joint between the frame boxes and the inner verticals good enough, or too much?
5. Add the top plate and other finishing touches.

Should I be using glue for the joints? And what about clamps? I think the clamps are what got me into trouble because it pushed one corner of the upper frame box too tight onto the vertical leg, causing it to bend and making the top unlevel. Would it be okay not to use those and just push the top down with my hands instead?

Also, I've been using glue with deck screws. Should I be using regular construction screws instead, 2-1/2"?

Thanks again for your help! I know I have a lot of questions. I've been working on this attempt for a couple weeks and I'm trying to get as much information as possible to increase the chances I'll be successful with my next attempt.

 

[Jedi1199]

This is a common issue with dimension lumber. You have to be very select in choosing what you buy. The cheapest stuff (which is the natural instinct) is sold "green". Meaning, it has a very high moisture content. Good enough to frame a wall or build a fence.. but, for a project like this, not so much... Problem is it tends to be twisted, or warped, or both.

I don't know if it is possible to start again from the ground up?

Kiln dried lumber, or pressure treated will be the most stable. Pressure treated is FAR more expensive, and also much heavier, but it will outlast the tank, the house, and your children.

 

[Bad Company]

With a stand you need two things:
1. A level, flat surface for the tank to rest with EVEN weight distribution. A 1/2" foam pad will help, but you need that top surface to be flat AND level.
2. A structure that will support the entire weight of the aquarium for years, even if it gets wet, bumped, etc.

IMPORTANT:
Your plywood looks like it has a curve to it. Plywood is almost never perfectly flat. Secure it to the 2X4s with screws and make it flat (sink the screw heads below the surface). Make sure you are using straight 2X4s.

Good luck!

 

[DaddyFish]

This isn't good news for you, but to give you an idea on typical lumber quality...
For my last tank stand project, I had to purchase four 2x8x16' to get two 6' lengths and two 24" lengths that were straight without knots. That's 64-feet of lumber to yield 16-feet of good quality material.

Good 2x4's are typically easier to find, but it takes a lot of weeding through stacks at Lowes. Even then I still dress cut the pieces for sizing.

 

[jeebsbyreef]

Thank you all for your help! I built a second one and it came out really straight.

One last question about glue. I’ve screwed everything together but didn’t apply glue. My plan was to remove the screws one the stand was straight, apply glue and put the screws back in. Is this a good idea? Will my stand lose some stability if I did this?

I’m also skinning 3 sides in 3/4” Baltic birchwood. Would this be good enough not to have to take the stand apart and add glue? Would it provide enough shear strength and support to the butt joints?

Thanks again!

 

[Jedi1199]

Thank you all for your help! I built a second one and it came out really straight.

One last question about glue. I’ve screwed everything together but didn’t apply glue. My plan was to remove the screws one the stand was straight, apply glue and put the screws back in. Is this a good idea? Will my stand lose some stability if I did this?

I’m also skinning 3 sides in 3/4” Baltic birchwood. Would this be good enough not to have to take the stand apart and add glue? Would it provide enough shear strength and support to the butt joints?

Thanks again!

I would glue it if it was me. You don't have a large tank, not supporting THAT much weight really.. You will most likely be just fine without it, especially once you get the outer "skin" on it. If you have the time, and don't mind the work, I would say glue it with a good marine glue. Water and wood are not happy companions..

Before you put on the skin, I would also seal the entire framework inside and out with several coats of a high quality wood sealer. Pat careful attention to the ends. The open end grain will absorb 3x as much sealant as the straight grain sides. Also be sure to seal all of the interior of the skin material (again, extra attention to the edges of the plywood, before you attach it.. then once you have done all of that you can stain and seal the exterior. Once you finish that, finish the entire stand, inside and out with a good high quality polyurethane finish. At least 3 coats. Do not use varnish or shellac for the finish. Polyurethane is basically liquid plastic and will provide a superior water resistant coating for the wood.