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Old 02/26/2007, 12:26 PM   #1
JohnL
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This thread was automatically split due to performance issues. You can find the rest of the thread here: http://reefcentral.com/forums/showth...18#post9339518


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Old 02/26/2007, 12:26 PM   #2
marcrunner
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James, here are my edges. After I pulled the pins, I pushed down on the sheet. Is this a bad idea? I am thinking that maybe I should have just let the weight of the panel do the pushing and not touch it?


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Old 02/26/2007, 02:39 PM   #3
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Welcome to Part III

Hiya Marc,
Coupla things:
If you had to lift the vertical piece to get the wires/pins in there, then you should release the clamps and let the vertical piece settle. Do not push down or "mash" the vertical piece to get ooze, you end up pushing the solvent out many times.
If you did not lift the vertical piece, just pushed down on the horizontal piece to get the wires/pins in, just let it be.
As you had guessed, let the weight of the panel do any pushing. You may have to shim, however, between the horizontal piece and the foam at times to make up for excess warpage in the horizontal piece.
I can't tell what kind of acrylic you have there (brand name) so can't tell if you joints are due *just* to the above or of the acrylic might have issues as well. Some brands of acrylic simply glue badly. This is why I only recommend Polycast, Acrylite GP, and Plexi-Glas G/GM

HTH?
James


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Old 02/26/2007, 03:49 PM   #4
bchbum189
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that looks to be an almost dry joint to me. I would say most def due to the pushing down on the piece. Youd be surprised how little weight is needed for the piece to glue flawlessly.


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Old 02/26/2007, 03:58 PM   #5
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Sorry for all of the ques. James, I am not sure of the brand as it was pulled from the scrap pile. With a good amount of force, I was able to pull those sheets apart--not a good sign. For my second set, I stepped up to a .22mm pin, for a larger gap between the sheets. I also used more solvent not worrying how big the pool of solvent was in front of me. These joints appear better, with that crazing look that I had before only residing on the outer edges of the joint. The center of the joint is perfectly clear, which I assume is what I am ultimately going for. I will post pics of those when it cures a little. If the joints were perfect, would I physically be able to pull the pieces apart?


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Old 02/26/2007, 04:24 PM   #6
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Quote:
Originally posted by marcrunner
Sorry for all of the ques. James, I am not sure of the brand as it was pulled from the scrap pile. With a good amount of force, I was able to pull those sheets apart--not a good sign. For my second set, I stepped up to a .22mm pin, for a larger gap between the sheets. I also used more solvent not worrying how big the pool of solvent was in front of me. These joints appear better, with that crazing look that I had before only residing on the outer edges of the joint. The center of the joint is perfectly clear, which I assume is what I am ultimately going for. I will post pics of those when it cures a little. If the joints were perfect, would I physically be able to pull the pieces apart?
The brand of acrylic is IMO a big deal, just being cell cast acrylic is simply not enough as there are varying degrees of quality among cast acrylic mfrs and the resins they use. So stick with the names noted above
If the joints were perfect, no - you would not be able to separate the pcs. You'd generally crack the acrylic first.

HTH,
James


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Old 02/26/2007, 07:21 PM   #7
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Hello Reef tank people

I don't have a reef tank but you guys seems to be the acrylic tank kings when it comes to information, so I thought your opinions would be helpful.

I recently purchased a 72x24x24 acrylic tank from a company that primarily makes tanks for big zoo's and public aquariums.

It's a turtle tank that I had made and added a custom cement backing with driftwood and the whole nine yards to create a natural look and habitat for turtles. The guy who built the cement backing also builds exhibits in the same kind of facilities.


There seem to be some confusion as to what level in the tank the water level would be at so the tank was built with 1/2" thick acrylic and top bracing that extends in 4 3/4" around the perimeter of the tank. There is no center braces as it would get in the way of a land area that was built behind the tank for the turtles to crawl onto.

I want the water level in the tank to be between 21 and 22 inches high but the manufacture doesn't want me to go higher than 18". Are they being overly caution?

I REALLY REALLY want the water level to be between 21 and 22 inches high as it looks much nicer and allows more swimming room.
What are your recommendations?

Thanks


Note*
Most turtle tanks don't have the water level at the top to allow for a basking area. Since I have an adjacent land area outside of the tank I can go higher.
Acrylite GP .472 thickness was the material used



Last edited by helter; 02/26/2007 at 07:50 PM.
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Old 02/26/2007, 08:14 PM   #8
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well IF you had a center btace ont he top you could go all the way full. I have my 96*24*24 in 1/2 inch but it has a full top with 2-18 inch by 24 inch access panels in the top.
I would come up with some way to make a center brace for peace of mind...you seem pretty creative Make it look like a tree limb or something

good luck


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Old 02/26/2007, 09:13 PM   #9
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I dont believe youd be able to "add" an effective center brace that would change the tanks current abilities as it would never be as strong as a solid top tank or much stronger than before the extra bracing. As for 1/2", you should be able to go to about 21-22" safely and having the 4 3/4" euro style brace does help.


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Old 02/26/2007, 10:06 PM   #10
helter
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It would be impossible to add a center brace. The cement backing extends up out of the water to meet the land area with a waterfall that drops down into the tank.

I recently raised the waterlevel about 2 weeks ago to the 21 and 22 inch mark. I have no bowing at all. But I would imagine that will change in the next couple of months.

Has anyone had long term success with no center brace and similar numbers?


thanks for the responses so far.


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Old 02/26/2007, 10:58 PM   #11
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Hiya Helter, welcome

The tank should hold water but will tend to bow out more over time, which I'm guessing you understand. I would generally say you should follow your mfr's recommendations as they have engineered the tank to hold a certain amount of force. I don't blame the mfr for being cautious and no, I don't think they're being "overly" cautious. They do this for a living and have seen the effects of water over time. I know I'd recommend similarly.
That said, and seeing that you have already raised the water level up...
If you start to see the back (inside) of the flange start to curve, I'd recommend you lower the water level. If there's enough force to curve 4.75" of acrylic, there's enough to potentially crack at the corner, esp if the corner is a tight radius. I'd be more comfortable if the corners of the access hole was fairly large, minimum 1". Sharp corners tend to concentrate stress and that's where the week spot will be so be on lookout for cracks in those areas. A visual example of the larger radius corners is in the pic below.

HTH,
James



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Old 02/27/2007, 08:48 PM   #12
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Acrylics,

thanks for the response.

I won't be able to check the back inner top as it is covered with cement. The weight load is on a 2X4 that is flush with the back side top of the tank. I can check the front and the left side of the top they are not covered.


I called the Mfg today and he told me the tank was spec for 12 inches of water although you can make it higher just keep an eye on the bowing. Huh?????
Evidently, he did this without ever discussing it with me or the other contractor.
I assumed when you buy a tank from a custom builder or Petco or Walmart it will hold water all the way to the top.


This is not what I wanted. But, I don't think their is anything I can do about it, as all the work has been done now.

At this point, I would rather have the tank burst open than live with a water level at half full. Would you guys be happy with your reef tank half full?

21 inches is what I'm planning to keep the water level at.
What would be the expected life of the tank at this level?

This has been a real learning experience. I did call some other tank builders today and I got different opinions on the recommended thickness the tank should be.

I guess, I just want to hear the tank will bow but should hold up anyway. At least to give me some peace of mind.



Last edited by helter; 02/27/2007 at 08:55 PM.
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Old 02/27/2007, 09:07 PM   #13
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I need to know about reusing the hypo applicator bottle, do I just clean it with acetone after I use it??


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Old 02/27/2007, 09:14 PM   #14
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it shouldn't get dirty, it will clog if you let off the pressure and it sucks melted acrylic/solvent back into the bottle. Ive been using the same needle everyday now for almost 4 months never cleaned.

I also found that the g string of a guitar fits into the needle nicely if you do clog it.


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Old 02/27/2007, 09:17 PM   #15
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ok thanks, I plan on using guitar string as my needles when gluing anyway


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Old 02/28/2007, 11:48 AM   #16
marcrunner
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Allright guys, I have spent the last couple days gluing joints. When I pull the pins, the sheet sets down lightly and it looks as though I will have a perfect joint. When I come back hours later, THe joint looks dry and crazed. I have tried using larger pins. Do you guys have any idea why my joints are not glassy clear and strong. THanx,Marc


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Old 02/28/2007, 04:12 PM   #17
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Hiya Marc,
Still need to know what breed of material you are using, as in brand name, and what solvent are you using?

James


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Old 02/28/2007, 05:11 PM   #18
H20ENG
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Marc,
Is your glue old? What type again? How about temperature in the room your gluing in? Is the stuff evaporating too fast, before melting all the way into the joint? Sounds like your tooling is fine, so I would suspect bad glue at this point Or as James mentioned, some oddball material???


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Old 02/28/2007, 07:06 PM   #19
marcrunner
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My solvent may be old. How old is old? I will ask the retailer what kind of acrylic I am working with. the sovent is WO-4. I am almost sure that there is enough wet solvent in the joint. thanx,Marc


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Old 02/28/2007, 08:39 PM   #20
Acrylics
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Old is one thing that is kinda hard to define precisely. The cans do not seal all that well and the first thing to evap is the methylene chloride which is the primary active ingredient. So in terms of age, can't say, but the concentration can easily change due to the evap so that your actual MC in the solvent goes way down rendering the solvent limited.

James


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Old 03/01/2007, 12:01 AM   #21
marcrunner
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I just checked the bottom of the can. It says APRIL 05. I opened it last week for the first time. Maybe I should move up to a .25mm needle for gap?


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Old 03/01/2007, 02:16 AM   #22
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I would suggest getting a new can of solvent. That is almost 2 years out of date.

Kim


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Old 03/01/2007, 07:20 AM   #23
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its less than $10 for a small can, so yes strongly recommend new solvent.


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Old 03/03/2007, 05:02 PM   #24
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Ok so i posted pics of the last lid I made and there were some improvements to be made. So here is my newest tank, 120"x24"x30", 5" lip all way around with 5" center braces and 3" minimum on each side of overflows between the braces if that makes sense.


Also polished up the outside edges



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Old 03/03/2007, 06:06 PM   #25
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Good job on the top braces.

My only suggestion is to use a round-over bit on the corners- may not matter to the customer, but it does make it look better, and removes sharp edges and corners for handling.


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