Acrylic Fabrication Q & A

[Turbo's Aquatics]

@TherealplexiG is correct here, because the back wall is a baffle (similar to a sump baffle) then your order of assembly flips so that you bond the front and back panels to the side panel.

You can build it normally (ends bonded to front then to back) but then you end up having to do things slightly differently - essentially, bond the ends to the front, then bond in the false wall, then the back. the problem is that the false wall firms up the end panels and if they are not dead-on perfectly aligned after that step, you're hosed - thing won't line up and you can't force them to, and you end up doing a lot of scraping.

So bond the front/back/false wall to one of the end panels, then the other end, then the baffles (which are not structural nor do they need to be 100% watertight). If you bond in the baffles first and then the last end (4th exterior wall) you can run into alignment issues. It's easier to scrape the edges of those baffles (where they bond to the bottom panel) than it is to adjust the juncture of the exterior panels.

Since acrylic is not always consistently thick or flat, even a panel being off by 0.001" of thickness can "translate" to 1/16" off at the other end of the panel. You then use the flexibility of acrylic to adjust that when making the 4th wall bond (or bottom panel bond) to compensate for that, but if you bond in perpendicular baffles along the way, you lose your flexibility. If that makes sense

 

[TherealplexiG]

the problem is that the false wall firms up the end panels and if they are not dead-on perfectly aligned after that step, you're hosed - thing won't line up and you can't force them to, and you end up doing a lot of scraping.

Exactly! That's where a jig is needed.. Or some sorta supports..

 

[cromag27]

So basically....... magic!

Arrgh¡
Here you go...
Wick the baffles to the false wall first..
You gotta go opposite of how you build a normal tank. Sides wicked to the back pane. Fix a single side to the back pane either one. Then you should either make some supports or jig for fixing the baffles and false wall assembly to the back pane. After that you can finish off with the other side to the end and then to the false wall. Lastly front panel. Further you know what to do.... Hope it makes sense to you...

 

[TherealplexiG]

So basically....... magic!

Enjoy flower plucker...haha

 

[cromag27]

Thanks guys, makes sense. someone want me to build them a 12 x 12 x 12 aio Pico. this makes no sense to me as there won't be much water on the display side. I've never owned a pico myself, nor have had the desire to. I guess it works?

 

[TherealplexiG]

Thanks guys, makes sense. someone want me to build them a 12 x 12 x 12 aio Pico. this makes no sense to me as there won't be much water on the display side. I've never owned a pico myself, nor have had the desire to. I guess it works?

Little wattah at display side?
Is it a vivarium?

 

[cromag27]

Salt tank.

Little wattah at display side?
Is it a vivarium?

 

[TherealplexiG]

Two part reactive cement being used..

 

[traumajeff]

Any thoughts on increasing the hole size on the top of an existing tank? Thought about a handheld router to make them slightly bigger. It's been mentioned that I might jeopardize the seams with vibrations.

 

[TherealplexiG]

Any thoughts on increasing the hole size on the top of an existing tank? Thought about a handheld router to make them slightly bigger. It's been mentioned that I might jeopardize the seams with vibrations.

Some go as crazy less as one of these.. Look at those openings.. Sure they integrate lot of structural support by dang at what cost?

 

[TherealplexiG]

@traumajeff
Could you post a pic of your tank?
Turbo is flooded these days.. There are others who could help... What are the dimensions of current opening / braces?

 

[Turbo's Aquatics]

Any thoughts on increasing the hole size on the top of an existing tank? Thought about a handheld router to make them slightly bigger. It's been mentioned that I might jeopardize the seams with vibrations.

vibration is not an issue. But you 100% have to use a template and a flush cutter - don't freehand it, that's for uber experts only...like James, who actually does freehand euro cutouts according to him

 

[traumajeff]

@traumajeff
Could you post a pic of your tank?
Turbo is flooded these days.. There are others who could help... What are the dimensions of current opening / braces?

It's hard to grab a pic right now. It's up and running. I'm wanting to do a full reboot in a few weeks. It's a standard 240g... 8x2x2

The openings are 12"x20" on the right and left sides & 10"x20" for the middle opening.

I don't want to get crazy... just a little bit bigger for more light penetration and ease of getting an arm in when needed.

The area between the holes is 10". From either side of the tank it's 8". It's 8" from the back of the tank to the larger 2 holes, and only 4" from the front of the tank.

I would love to make the 2 larger holes bigger towards the back of the tank, and thin out the area between the middle and the larger 2.

 

[Turbo's Aquatics]

oh you're talking about trimming out the eurobrace, I thought you just wanted to make a bulkhead hole larger or something...that's different. This gets into the width of the euro now and future, distance from walls, thickness of material, brand of material, lots of factors. Personally I wouldn't touch it

 

[TherealplexiG]

@traumajeff
Trauma to trim.. Leave it as Turbo says..

 

[traumajeff]

oh you're talking about trimming out the eurobrace, I thought you just wanted to make a bulkhead hole larger or something...that's different. This gets into the width of the euro now and future, distance from walls, thickness of material, brand of material, lots of factors. Personally I wouldn't touch it

Thanks for helping. I've seen similar tanks with wider openings, so I figured I'd look into it.

 

[Turbo's Aquatics]

give us measurements & a sketch, there might be room...

 

[traumajeff]

give us measurements & a sketch, there might be room...

Sorry it's kind of messy.

I was thinking of moving the larger holes over to the 6" mark from the side, and then back to the 4" mark.

I then wanted to open up the middle hole some too. I didn't know if I should just open that hole, or widen it and the larger holes, leaving 6" between the middle and each of the larger holes.

 

[singleshot]

Ok a couple questions, I know we shouldn't use a laser to cut then bond due to it will make it craze but what about a water jet?? Is weld on 16 ok to use haven't seen anyone mentioning that one.

 

[Turbo's Aquatics]

Sorry it's kind of messy.

I was thinking of moving the larger holes over to the 6" mark from the side, and then back to the 4" mark.

I then wanted to open up the middle hole some too. I didn't know if I should just open that hole, or widen it and the larger holes, leaving 6" between the middle and each of the larger holes.

Normally an 8' tank would have a 3" perimeter and 3x 6" crossbraces every 24". Removing one opening would mean you would want to add 2" to the crossbrace width, making it 8" and make the perimeter 4.5".

This also assumes that the material is good and the proper thickness. For an 8x2x2 that would be 3/4" walls (normally a 24" tall tank would be 1/2", but James/Acrylics recommends jumping up a thickness at 8' to keep deflection down). I can't tell what your material thicknesses are but it looks like it's at least 1/2" on the top and walls?

If it is 1/2" then I wouldn't narrow the perimeter to less than 6" on the sides, and you're already at 4" on the front. I'd be careful about the back euro width because of the trapezoid opening on the back, which is flush with the back panel and generally makes for a weak spot in the structure. So you don't want to expand the side holes toward the back as a square opening because that would decrease the euro width between the corners of those holes and the trap, which is exactly where it will crack out if it does. What you *could* do is expand backward making a 5-sided hole that maintains the distance like this

But even that might be pushing it. If you did this, you would want to maintain minimum 3" diameter (1.5" radius) inner corners with no jagged edges (smooth curves, all around) and then a 1/8" roundover on the top and at least scrape off the sharp edge on the underside. The point is that any sharp corner, transition from straight to inner corner, edge, etc that has a point on it is where the stress will focus. That's one thing I did learn from my discussions with a guy from Cyro...even taking a few passes with a razor blade at a 45 degree angle to a fresh router cut edge will remove all the point stress. Rounding it (either router or sanding) is even better. It's not just a presentation thing, it is a structural/stress reliever.

Ok a couple questions, I know we shouldn't use a laser to cut then bond due to it will make it craze but what about a water jet?? Is weld on 16 ok to use haven't seen anyone mentioning that one.

Water jet does not leave a weldable edge. Weld-on #16 is junk, lots of fillers, not good for structural joint. It has it's place, you can use it for non-structural items, and you can use it to build up layers on a leaky joint like a baffle in a sump, and some have used it to seal up a poor exterior joint but it's shaky even for that. That being said I've seen at least one frag tank at a show that was built with saw cut edges and probably 10 layers of 16 on the inner corners, I thought that sucker was going to blow right in front of me but he said it lasted for years!!