# Aquarium Stand - Pocket holes between dowels?



## Chichas (9 mo ago)

I'm building this stand for my aquarium. It's 3/4 Hickory ply. I've placed dowels top and bottom on the 2 side panels and then on the back panel, I drilled pocket holes every 6 inches on every side. The back sits inside the top, bottom, and 2 sides.
I had planned on doing 4 pocket holes on the left and right side panels between the dowels. Since the inside of the cabinet will be painted, once I plug the holes and paint, you will never see them. So the question is, will I gain any strength of the joint by adding the screws to a dowelled and glued joint? My plan is to glue and clamp up all along the joints with dowels.

Here are some pics of what I've put together:




































(Behind this front panel will be a stretcher made from 2 pieces of 3/4 ply glued and screwed together and then pocket hole screwed into the side panels. I'll then run screws through it into the front panel.)


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## corelz125 (Sep 23, 2015)

How big is the tank? Is it going to be filled with water? If it is I would use some type of framing not just plywood.


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## Chichas (9 mo ago)

Yes, it's an aquarium, 80 gallon saltwater aquarium. If you've ever seen a commercial aquarium stand, they are usually MDF with melanine veneer and cam lock connections with some dowels. You would not believe they would hold up an aquarium but they do. 
Many folks will use 2×4 frames with plywood because it's just easy to work with and not exactly necessary.


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## Unknowncraftsman (Jun 23, 2013)

I was thinking the same thing. When I used to build tanks for buddy that has a reef tank business I always built a frame of 2×4. The structural part was somewhat separate from the pretty part.
Consider adding something in the corners. I know tank guys love space for pumps and sump .
Even a 2×2 gorilla glued in the corners is better then nothing.
Good Luck


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## Chichas (9 mo ago)

> I was thinking the same thing. When I used to build tanks for buddy that has a reef tank business I always built a frame of 2×4. The structural part was somewhat separate from the pretty part.
> Consider adding something in the corners. I know tank guys love space for pumps and sump .
> Even a 2×2 gorilla glued in the corners is better then nothing.
> Good Luck
> ...


Ah, you got some experience with this. Cool. I'm a little fuzzy on the 2×2 idea. Is that running the length up the sides and back? Can't do that, sump won't fit. My research tells me that the main idea is prevent racking from side to side. The stand is all dry fit right now and no b screws in the back panel and it's solid when pushing on one side. I see no flex on the other.


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## pottz (Sep 15, 2015)

well your looking at about 750-800lbs my friend. as in the movie jaws when they see the shark and says,your gonna need a bigger boat !!! well your gonna need a hell of a lot stronger stand my friend. what your making is a huge accident waiting to happen.id say scrap what youve done and re engineer. you need a strong frame for that much water plus weight of the tank.back to the drawing board.


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## Chichas (9 mo ago)

> well your looking at about 750-800lbs my friend. as in the movie jaws when they see the shark and says,your gonna need a bigger boat !!! well your gonna need a hell of a lot stronger stand my friend. what your making is a huge accident waiting to happen.id say scrap what youve done and re engineer. you need a strong frame for that much water plus weight of the tank.back to the drawing board.
> 
> - pottz


I can show you any number of stands built similarly that hold larger tanks than mine.


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## pottz (Sep 15, 2015)

> well your looking at about 750-800lbs my friend. as in the movie jaws when they see the shark and says,your gonna need a bigger boat !!! well your gonna need a hell of a lot stronger stand my friend. what your making is a huge accident waiting to happen.id say scrap what youve done and re engineer. you need a strong frame for that much water plus weight of the tank.back to the drawing board.
> 
> - pottz
> 
> ...


not in my house you wont.if your gonna rely on plywood and pocket screws alone,good luck. please post some pic's of those stands your talking about.


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## Chichas (9 mo ago)

> well your looking at about 750-800lbs my friend. as in the movie jaws when they see the shark and says,your gonna need a bigger boat !!! well your gonna need a hell of a lot stronger stand my friend. what your making is a huge accident waiting to happen.id say scrap what youve done and re engineer. you need a strong frame for that much water plus weight of the tank.back to the drawing board.
> 
> - pottz
> 
> ...


You don't read thoroughly, do you?


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## Chichas (9 mo ago)

> well your looking at about 750-800lbs my friend. as in the movie jaws when they see the shark and says,your gonna need a bigger boat !!! well your gonna need a hell of a lot stronger stand my friend. what your making is a huge accident waiting to happen.id say scrap what youve done and re engineer. you need a strong frame for that much water plus weight of the tank.back to the drawing board.
> 
> - pottz
> 
> ...


Here is an example of a commercial stand, made with MDF.

https://www.reef2reef.com/threads/new-build-red-sea-reefer-peninsula-500.344388/


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## Lazyman (Aug 8, 2014)

I think that the plywood sides and back will be pretty strong, though the front corners need more support, IMO. If you think about it, four 2×4s in the corners are less wood than the 3 sides of plywood as long as the joinery prevents them from bowing out our racking. The dowels and pocket screws (and glue) on the back panel will prevent that. My concern is with the top and front apron, stretcher or whatever that header is called. I think that doubling it up makes it strong enough but I would want support under it, not just attached to the front. I probably would have put it under the top, like the apron of a table and if you add a vertical strip under each end on the front, that adds more support and also makes the front corners stronger (attach them to the sides with pocket screws). I built plywood legs for my "assembly/outfeed table (see below) and the legs are plenty strong. I have had 400-500 lbs on it and it seemed rock solid. It also would not hurt to put a piece under the top in the middle connecting the front header to the back. My 2-cents.


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## corelz125 (Sep 23, 2015)

That particle board one has a little more support to it. It has the one piece in the middle. Like Nathan mentioned it needs a little more in the front to keep it from racking.


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## sunnybob (Oct 12, 2021)

I owned a small tropical fish shop with over a 100 tanks, I built many stands and even my own glass tanks.
I would not trust that structure with 80 gallons of water on top.
Have you considered centre sag? Many tanks on home made stand crack across the bottom because the base sags and the entire weight is on the four corners.


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## Chichas (9 mo ago)

> I think that the plywood sides and back will be pretty strong, though the front corners need more support, IMO. If you think about it, four 2×4s in the corners are less wood than the 3 sides of plywood as long as the joinery prevents them from bowing out our racking. The dowels and pocket screws (and glue) on the back panel will prevent that. My concern is with the top and front apron, stretcher or whatever that header is called. I think that doubling it up makes it strong enough but I would want support under it, not just attached to the front. I probably would have put it under the top, like the apron of a table and if you add a vertical strip under each end on the front, that adds more support and also makes the front corners stronger (attach them to the sides with pocket screws). I built plywood legs for my "assembly/outfeed table (see below) and the legs are plenty strong. I have had 400-500 lbs on it and it seemed rock solid. It also would not hurt to put a piece under the top in the middle connecting the front header to the back. My 2-cents.
> 
> 
> 
> - Lazyman


Thanks Nathan. If you look at 5th pic that shows the front top panel, I mentioned doing your idea of doubling up a stretcher behind that and it would be directly under the top. Good idea! 
I did also consider adding a center upright brace once the sump is in. I like that idea.I'm on the fence about that. It has some benefit other than supporting the front side as it will also block light from escaping the gap between the doors. There's a light that will be on inside the cabinet during the night and it would be nice to block that.


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## Chichas (9 mo ago)

> That particle board one has a little more support to it. It has the one piece in the middle. Like Nathan mentioned it needs a little more in the front to keep it from racking.
> 
> - corelz125


Racking or sagging?


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## pottz (Sep 15, 2015)

> I owned a small tropical fish shop with over a 100 tanks, I built many stands and even my own glass tanks.
> I would not trust that structure with 80 gallons of water on top.
> Have you considered centre sag? Many tanks on home made stand crack across the bottom because the base sags and the entire weight is on the four corners.
> 
> - sunnybob


+1


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## Chichas (9 mo ago)

> I owned a small tropical fish shop with over a 100 tanks, I built many stands and even my own glass tanks.
> I would not trust that structure with 80 gallons of water on top.
> Have you considered centre sag? Many tanks on home made stand crack across the bottom because the base sags and the entire weight is on the four corners.
> 
> - sunnybob


Unclear on this. You're referring to glass tanks? Glass only require support along the edge of the aquarium. Acrylic requires support across the entire bottom? Do you have any thoughts on the way commercial stands are constructed? Here's an example:

https://www.reef2reef.com/threads/new-build-red-sea-reefer-peninsula-500.344388/


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## pottz (Sep 15, 2015)

> That particle board one has a little more support to it. It has the one piece in the middle. Like Nathan mentioned it needs a little more in the front to keep it from racking.
> 
> - corelz125
> 
> ...


these words confuse you ? oh boy!!!!


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## Unknowncraftsman (Jun 23, 2013)

Sunny Bob is correct. I remember tanks need support in the corners. I've set up lots of the stands I made and always made sure the surface that the tank sits was flat so the stand would not twist. A twist will wreak a Acrylic tank faster then a glass one.
Care should be taken for both 
I remember the glass tanks that we picked up in San Diego had a floating bottom. 
2×2 vertical in the corners is what I was thinking.
Good Luck


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## sunnybob (Oct 12, 2021)

You are completely wrong about glass only needing corner supports. Glass is very weak if subjected to bowing pressure.
You might be thinking about the weight of water being evenly spread over the entire surface, but what about rocks and gravel and sand? All of that weight is directed downwards only. A large rock placed centrally in any tank will result in the base bowing.

I have made hundreds of glass tanks, in thicknesses up to 10 mm plate glass, and I would not allow ANY of them to stand on an unsupported flat surface.
An Aquarium shop should sell a 12 mm thick polystyrene (styrofoam) sheet for under the tank to absorb any imperfections. A single grain of grit under a large tank will exert enough localised upwards pressure to crack the glass. by the same token, if its a large tank, a solid full sized piece of polystyrene should not be used, as it will compress at the edges but not in the middle, causing an upwards bulge that will also split an all glass tank base.

You of course are at liberty to completely ignore all the good advice you have been given if it doesnt agree with your inexperienced perceptions.


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## sunnybob (Oct 12, 2021)

Another point often overlooked by beginners….
They calculate the weight of water (sometimes) but then forget to add the weight of the tank itself, all the gravel and adornments, and even the fish if they are large. 
That will normally DOUBLE the weight of the entire set up, sometimes even more than double.


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## BurlyBob (Mar 13, 2012)

I've got agree with the negative comments on pocket holes. They've got on strength, period. They are great for face frame stuff. You need to dados and much stronger joinery. Re think your needs. Seriously.


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## Chichas (9 mo ago)

> That particle board one has a little more support to it. It has the one piece in the middle. Like Nathan mentioned it needs a little more in the front to keep it from racking.
> 
> - corelz125
> 
> ...


No, they are 2 different things. Racking refers to sheer force from the side that could cause one of the sides to blow out where it meets the top or bottom panel. Sagging refers to the top piece of plywood bowing downward. Are you always this grumpy?


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## turningandburning (10 mo ago)

A majority of the replies, many of which coming from experienced people are telling you to rethink and your response again and again is to rebuff. Always referring back to how "commercial" stands are constructed.

I wouldn't be basing my design on a cheap big-box stand that is designed and made to a price point (ie cheap as possible). It's your house and your mess, you do you.

80 gal of water is ~670lbs
rocks and deco ~100-150lbs
weight of tank itself ~150lbs

We're @ nearly 1,000 lbs and haven't calculated for lights or anything else that may hang on the tank and add weight that needs supporting.

I've made tank stands in the past, all were constructed with 2×2 frames.
Yes, I sleep well at night.


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## Unknowncraftsman (Jun 23, 2013)

> A majority of the replies, many of which coming from experienced people are telling you to rethink and your response again and again is to rebuff. Always referring back to how "commercial" stands are constructed.
> 
> I wouldn t be basing my design on a cheap big-box stand that is designed and made to a price point (ie cheap as possible). It s your house and your mess, you do you.
> 
> ...


Don't forget the weight of the fish. 
The most important part


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## pottz (Sep 15, 2015)

> That particle board one has a little more support to it. It has the one piece in the middle. Like Nathan mentioned it needs a little more in the front to keep it from racking.
> 
> - corelz125
> 
> ...


are you always this cocky and arrogant ?


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## rwe2156 (May 7, 2014)

Doesn't it depend on how the tank is made?

Many years ago, I had an L shaped 80 gallon salt water glass tank. It was an older tank that had a metal frame around the glass. I remember even empty it weighed a ton. It came with a wrought iron stand with no bottom only the edges were supported. I never gave it a second thought, because the stand came with the tank. I never had an issue, but reading these posts, and thinking about the weight on the bottom. Maybe the glass was thicker?

I eventually took the tank down, and I remember dropping a pretty heavy piece of corral on the glass when it was empty. I didn't break it, so I'm guessing the bottom was made of thick glass.

All that said, the commercial stands that a pictured must work or they wouldn't be in business long. They do look too flimsy to me considering the weight, but plywood and melamine have tremendous vertical strength.

To the OP: In reference to the pics you cited, one has a face frame the other has a vertical divider. Both of which you should be thinking about using in your stand.

But what do I know…...................


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## SMP (Aug 29, 2018)

> You are completely wrong about glass only needing corner supports. Glass is very weak if subjected to bowing pressure.
> You might be thinking about the weight of water being evenly spread over the entire surface, but what about rocks and gravel and sand? All of that weight is directed downwards only. A large rock placed centrally in any tank will result in the base bowing.
> 
> I have made hundreds of glass tanks, in thicknesses up to 10 mm plate glass, and I would not allow ANY of them to stand on an unsupported flat surface.
> ...


One of my first jobs in high school was in a fish room of a large pet store. I agree with the above. Personally have seen a few tanks spontaneously start leaking or bottoms shatter. Some that were fine for years, and then one day you are walking the rounds and you hear the dreaded "crack,splish" sound that is so obvious the second time lol. With luck you will be home when it happens and can save the fish at least. I had a tank once where the fish alone were worth probably $500 (this was back in early 90s)


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## Chichas (9 mo ago)

well, I could sit here all day and defend, explain or show examples. But I'm not going to. Some folks are helpful and ask questions and offer good suggestions. I appreciate that. 
My question was about combining screws along with the dowels and glue. Which was never answered. Dowels and glue appear to be stronger to me from my research than the wood screws and cam lock fittings used on many commercial stands made of MDF. So if you have any thoughts on that other than "pocket holes are for losers" it would be great to hear.


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## Chichas (9 mo ago)

> That particle board one has a little more support to it. It has the one piece in the middle. Like Nathan mentioned it needs a little more in the front to keep it from racking.
> 
> - corelz125
> 
> ...


you dished out the insult, I just served it back to you.


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## Chichas (9 mo ago)

> One of my first jobs in high school was in a fish room of a large pet store. I agree with the above. Personally have seen a few tanks spontaneously start leaking or bottoms shatter. Some that were fine for years, and then one day you are walking the rounds and you hear the dreaded "crack,splish" sound that is so obvious the second time lol. With luck you will be home when it happens and can save the fish at least. I had a tank once where the fish alone were worth probably $500 (this was back in early 90s)
> 
> - SMP


Marine Land Deep Dimensions seem to be notorious for that. I can think a half dozen or more that were on mfg provided stands and split a seam.


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## Chichas (9 mo ago)

> Don't forget the weight of the fish.
> The most important part
> 
> - Aj2


That was funny!


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## LeeRoyMan (Feb 23, 2019)

"well, I could sit here all day and defend, explain or show examples"

Judging by your responses, I think you already had your mind made up on how you were going to do it.
Maybe just looking for validation?

"Dowels and glue appear to be stronger to me from my research"

I don't think I read anyone say "pocket holes are for losers". I did see one comment that added they're not good for strength. Valid comment for you to decide it's worth.

A lot of people took time to try to help you.


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## Kudzupatch (Feb 3, 2015)

I see this over and over from people that really don't know what they are talking about.
YOU MUST USE 4X4'S! 2X4 FRAME MINIMUM! YADA, YADA, YADA.

Let me say right now, I quit reading LONG before I got through all the comments. I have seen/read/heard it all before. Over and over!

You don't need 2×4 or heavy frame work to support the weight of 4 grown men, which is basically what you are talking about.

The load is in compression, pushing down on the stand/wood and what you have should be fine assuming good wood and good construction methods. 800 lbs is not enough weight to crush the wood assuming it is good shape and good joints.

*What you do have to be concerned about it racking and a flat top.*

You can not have any wobble in the stand or it could just lay over and fold up. When I build something like that I want a sold back (plywood) attached securely to frame.

Then I want to have a face frame around the front. That will make a very rigid box with no wobble. To me ANY wobble means it is not safe. It is tempting but don't skip on the front face frame. It makes a big difference!


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## LeeRoyMan (Feb 23, 2019)

> *What you do have to be concerned about it racking and a flat top.*
> 
> You can not have any wobble in the stand or it could just lay over and fold up. When I build something like that I want a sold back (plywood) attached securely to frame.
> 
> ...


This seems to be the area of concern, The dowels and glue are good but the pocket screwed cleats behind the front aren't going to help as much as thought. (MY Opinion)
I would figure a better way to strengthen the front to keep the front from racking.


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## Kudzupatch (Feb 3, 2015)

> ........My question was about combining screws along with the dowels and glue. Which was never answered. Dowels and glue appear to be stronger to me from my research than the wood screws and cam lock fittings used on many commercial stands made of MDF. So if you have any thoughts on that other than "pocket holes are for losers" it would be great to hear.
> 
> - Chichas


I missed that question and got wrapped up in the BS being spouted.

They can't hurt. Glue is plenty strong but I have glued and screwed a few joints for something really heavy and would see a lot of force on it. Perfect example is some Mobile bases for some heavy machines I made. I know if the glue joint ever moves at all it will keep going to it fails. So I added some screws to prevent that movement.

I am not sure yours are needed but it can't hurt.


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## Lazyman (Aug 8, 2014)

I can't tell the dimensions exactly so I assumed it is 24×48". Assuming 3/4" fir plywood top, 1.5×3" edge strip (header) and even with 1000 lbs evenly distributed load, the sagulator says that the sag is acceptable (0.06 total). Note that the sagulator assumes no support along the back-just at the ends and an edge strip. Put the header under the the top, add a center support in the front and beef up the front corners and the span is more than halved and the sag is negligible. With the center support, you can get away with a 3/4" header.

So that just leaves racking. As long as the joints are sound and are made so that racking cannot happen, I think that the vertical strength of the plywood sides is greater than a 2×2 frame would be. I think that the glue, dowels and pocket screws in the back will stiffen the frame nicely and adding strips in the front to effectively make 2 more corners will make it even more solid. It would not hurt to add 2×2 strips in the corners to act as a cleat to help beef up the vertical joints for a little insurance but it is probably not necessary for vertical support.


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## Chichas (9 mo ago)

> I see this over and over from people that really don t know what they are talking about.
> YOU MUST USE 4X4 S! 2X4 FRAME MINIMUM! YADA, YADA, YADA.
> 
> Let me say right now, I quit reading LONG before I got through all the comments. I have seen/read/heard it all before. Over and over!
> ...


very helpful, thank you.


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## Chichas (9 mo ago)

> I can t tell the dimensions exactly so I assumed it is 24×48". Assuming 3/4" fir plywood top, 1.5×3" edge strip (header) and even with 1000 lbs evenly distributed load, the sagulator says that the the sag is acceptable (0.06 total). Note that the sagulator assumes no support along the back-just at the ends and an edge strip. Put the header under the the top, add a center support in the front and beef up the front corners and the span is more than halved and the sag is negligible. With the center support, you can get away with a 3/4" header.
> 
> So that just leaves racking. As long as the joints are sound and are made so that racking cannot happen, I think that the vertical strength of the plywood sides is greater than a 2×2 frame would be. I think that the glue, dowels and pocket screws in the back will stiffen the frame nicely and adding strips in the front to effectively make 2 more corners will make it even more solid. It would not hurt to add 2×2 strips in the corners to act as a cleat to help beef up the vertical joints for a little insurance but it is probably not necessary for vertical support.
> 
> - Lazyman


you are dead on for the dimensions. The header you refer to is the board on the outside of the box? That one is 3/4 ply, 4.75" wide. This was great info, appreciate it. I will probably hove some questions later this week. I'll probably just PM you.


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## Lazyman (Aug 8, 2014)

Yes, that is the header (not sure what else to call it). It will probably work okay the way you show it but by putting it underneath the top, it just feels a little more sturdy to me. It also makes it so that the side and center supports rest on the bottom of the cabinet rather than attached to the outside.


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## Chichas (9 mo ago)

> Yes, that is the header (not sure what else to call it). It will probably work okay the way you show it but by putting it underneath the top, it just feels a little more sturdy to me. It also makes it so that the side and center supports rest on the bottom of the cabinet rather than attached to the outside.
> 
> - Lazyman


i agree. The plan is/was to place a double laminated 4" wide 'beam' under the top (made from 2 pieces of the 3/4 ply) that would be glued and screwed together. The 'beam' would be screwed into the sides and then then through it into the header as well. I'm with you on the center support. Sounds like we are on the same page?


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## northwoodsman (Feb 22, 2008)

My concern would also be the racking. I have been watching this from the very first post. 
1) When you drilled in for the dowels you left little material on the outside edge. You could have probably broken through that wall just by pushing hard enough on the dowel with your fingers. In this case the dowels did little more than help with alignment.
2) Glue is very strong, and likely stronger than the dowel or the pocket screws, but it still is adhering end grain plywood to a thin layer of veneer.
3) That leaves the pocket screws. The structural integrity of these are limited by 1) did you use the correct type (both thread type and screw head), 2) the quality of the layers of the plywood, 3) is the depth of the hole correct leaving enough of a shoulder for strength, and 4) did you use the proper torque or did you use too much splitting the wood or damaging the shoulder that the screw head rests on?
4) Those cam lock fittings are only as strong as the surrounding material, at least the good quality ones. Some are even weaker than the particle board they are designed to go in.

Looking at one of the examples that you provided it looks like the base was L-shaped, which would prevent racking. I thought I saw another one where the base was part of another structure which would have prevented racking. I would try to provide some additional support inside that base cabinet any way possible, it's better to over build than under build. I wouldn't be as worried about the tank leaking as I would the whole thing come crashing down to the floor and injuring someone. I can't imagine what kind of injuries that could cause to people or pets, or what it would be like to clean up that mess.

What I see is someone who reached out for advice and several experienced woodworkers, experienced cabinet builders, and even experienced aquarium people who responded with sound advice. Not one person in the group suggested that you proceed as planned or supported your decision. It's not like some supported it and some were against it, they are 100% against it. There is one person who is semi-on board but even he is making suggestions to modify. You have built a beautiful cabinet. Great choice of materials and craftmanship. I'd like to see you implement some of the suggestions just to be sure those efforts aren't wasted. What if you ever decide to sell it or give it away?


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