Acrylic fabrication questions? I can help!

[CenterConsole]

I’m considering buying a used acrylic tank that has no overflow. I wanted to weld up a long external over flow supported with triangle braces and drill 3 holes in it for a bean animal drain. I was going to drill small holes in a row along the top of the tank as teeth to flow into a coast to coast style overflow. I don’t have any real prior acrylic experience and am worried about bonding an external overflow to the tank, having it break off and leaking everywhere. Any suggestions?

[lapin]

Originally Posted by CenterConsole

I’m considering buying a used acrylic tank that has no overflow. I wanted to weld up a long external over flow supported with triangle braces and drill 3 holes in it for a bean animal drain. I was going to drill small holes in a row along the top of the tank as teeth to flow into a coast to coast style overflow. I don’t have any real prior acrylic experience and am worried about bonding an external overflow to the tank, having it break off and leaking everywhere. Any suggestions?

In response to part 1. If you do this, be sure the "used tank" is not warped from bowing. The side you want to weld the overflow to must be perfectly even across the length. The surface needs to be perfectly clean for a bubble free seam. You should practice welding and then practice some more. It is not easy to get a bubble free seam and you need that for strength.

[CenterConsole]

Sounds like I’m in over my head on this project. The tank isn’t definitely older and used, I’m sure it has bowed some especially given it’s tall dimensions.

[LJLKRL]

Originally Posted by Floyd R Turbo

Upcut bit means the chips are pulled toward the router. So when the router is installed facing up in a table, up is down. The chips get pulled "up" relative to the router which is down.

When you have a template and are using a flush trimming bit (which has the bearing on the tip) then you will want the template on top of the material.

Now the big trick is making the template. I made an overflow template out of 3/8" scrap and that took several hours. What I did was tape a piece down as the depth stop, then tape a piece down that was perpendicular to that and make one notch. Then move the perpendicular stop 1/2" and make another cut. Repeat for as long of a template as you need. Mine is 48" so that took a while.

But now you can take that template and stick it down to your work and making an overflow takes just a few minutes.

I finally got around to playing with the router. I bought some acrylic from Home Depot and used an overflow box I bought online for a template.
I got a spiral upcut bit with the bearing on the end of the bit.
I am amazed at how simple it was to cut the teeth and how clean they came out.
I made a cover for the overflow box to the exact size, which I was also amazed at how simple it was.
One thing for sure though, the spiral bit spews shavings like crazy, and they go under the table away from the vacuum which is on top. I have to come up with a solution to this because it makes a huge mess.
All in all though, I love this thing!

[pandimus]

Originally Posted by Floyd R Turbo

I use 2 pieces of wood (I think 3/4" plywood) that I put a few heavy bolts through (with washers) to hold a standard box cutter razor blade in between, tighten the bolts and it holds it nice and tight.

I use this for the specific thing you are describing. When you bond 2 panels together, it's rare that you get it 100% perfect on both ends of the joint. Inevitably, you end up with a tiny lip that you can feel with your fingernail. But usually, I end up with a smudgey little area there anyways because as I'm lining things up after pulling the pins, using my fingernails to feel how things are lining up, this wicks some solvent over to the edge and I end up with some dried up solvent on the surface of the corner that will eventually be part of the top/bottom joint. You need to take this off anyways or you will end up with bubbles in the corner, usually.

So I take the scraper and position the blade so that it is across both pieces of the joint, give it a slight angle toward the corner of the joint, and scrape. Here is where another trick I've learned comes into play - do this BEFORE you flush trim the vertical joint. The reason is that the downward pressure you apply when scraping across the assembly is fine until you get to the outer corner, where all your pressure is now right on that point and this tends to result in a bit more material being removed with each pass. The result is that you essentially will end up rounding off that corner and you will have a gap in the joint. If you leave the lip on while scraping, this area will get flush trimmed off so you don't care if it gets rounded.

I leave all the lips on until the tank is fully assembled. Leaving the lips on the side/front & side/back joints results in a little more material right at that outside corner, and this further reduces the tendency for air to get into the joint at the corner (which are prone to it, since there are 2 sides for the solvent to evap out of). Then if it does you just trim it off and you're usually ok

On the MAPP gas. No flame polishing, IMO. The happy medium that I have found is using a roundover bit (usually only 1/8" on material less than 1/2" thick, 1/4" past that) and then wet sanding. On vertical outer seams you can get away with a bit less than you would for a scratch removal on a flat panel. I use 600, 800, 1200, then 1500. Sometimes 400 depending on how good the corner round bit worked (not always perfect). But all you need to know is that the first pass/grit, do this one well enough to make everything smooth (take out the router bit pattern, completely) and then all the progressive passes are pretty much smooth sailing. When you are done with the 1500 pass, then make a pass with Meguair's Ultra Cut and a Black & Decker random orbital buffer ($35 at lowes) with the blue sponge pad, and then if you want another pass with the Swirl Free polish. Use lots of blue tape to protect the areas you don't want scuffed up by sanding or polishing. Takes a bit of practice.

Alternatively you can go straight to the polisher, if you don't care about seeing the router marks. The polisher will diminish the rough-cut look of a router-trimmed edge, it will shine it up pretty well actually. You can also achieve this by using a 3-stitch wheel on an arbor bit & drill at high speed. Using the Meguiars, or another plastic polish usually is OK too (on outside of tank, can use about anything because it never gets in contact with tank water). Again, use plenty of blue tape to protect the area you don't want hit with the buffing wheel.

I think ive seen pics, and their probably in this thread, but curious if you mind showing your razor setup again?

[pandimus]

Originally Posted by pandimus

I think ive seen pics, and their probably in this thread, but curious if you mind showing your razor setup again?

Actually nevermind, I found a pic on Melvs reef..

[pandimus]

I know its a week or two to let the sump cure before using it. Does that mean no leak check until then?

[Floyd R Turbo]

Leak check is fine. It's slow adsorption of water while the solvent is fully curing that can cause problems.

[pandimus]

Just want say thanks to all of you.. after many months of planning designing and screwing things up I finished my sump...

Sent from my Pixel 2 XL using Tapatalk

[lapin]

your hired )))

[Floyd R Turbo]

Nice!

[thejuggernaut]

I am thinking about making my own skimmer. Do any of you have any experience with how they make the cone section. I am assuming it is just a mold where they pull a softened (heated) sheet of acrylic over it. Possible under a vacuum. My questions is how do they finish the mold so that it doesn't create a crummy finish on the inside of the cone.

I am assuming the heat of the panel has allot to do with it. Heat it too much and the surface will be too soft and will pick up imperfections in the mold. Too cold and it wont form to it properly. Either way, does anyone know where I could do more research on it?

[ReefingHavoc]

Building my first sump out of 1/2" cell cast acrylic. Dimensions are 48x18x20. There will be 3 - 1/8" baffles in the sump. What kind of top bracing is recommended (full, euro, none)?


Thanks -

[lapin]

I would go with a 3" strip around the top. Does not have to be 1 solid piece. Since you have baffles you dont need cross bracing. Im assuming the baffles divide the sump into 3 sort of equal chambers?

[ReefingHavoc]

Originally Posted by lapin

I would go with a 3" strip around the top. Does not have to be 1 solid piece. Since you have baffles you dont need cross bracing. Im assuming the baffles divide the sump into 3 sort of equal chambers?

Thanks for the feedback. The chambers will be about 10%, 40%, 30%, 20%

[IUfan]

Thinking of building a RODI reservoir, space is limited so I can’t use a standard barrel or trash can. Was going to build a large rectangular acrylic box.

I would like to double the reservoir as a Stand for a 10 gallon QT tank.

Think the below design could work?

Any adjustments to help support the 10g tank?

What thickness of Acrylic would you recommend if so?





Sent from my iPhone using Tapatalk

[lapin]

Will the QT be a glass tank with frame on the bottom? Will it be 12" wide or 11.5?

[IUfan]

It’s a glass tank with a frame around the bottom. 20.25”X10.5”


Sent from my iPhone using Tapatalk

[IUfan]

Should I make it the same width as the 10gallon tank then, so the sides are supporting the tank?


Sent from my iPhone using Tapatalk

[paphater]

I am very much an amateur with acrylics but my first tank (96"x24"x24") is still leak free after two years. But when I built that tank I did it with freshwater in mind and I'd like some more depth so I'm planning a new build. It'll be a flat back hex and I'm toying with the idea making the viewing window a single acrylic piece. How feasible would it be to use weld on 40 to create those angles?

[Floyd R Turbo]

You don't "need" weld on 40 for anything under about 2" thick.

The hard part on the FB Hex will be 1) bending or 2) cutting angles & bonding angles

[paphater]

I was hoping to you use 40 because I figured it would be more forgiving on those angled edges. I'm not sure how I would finish them other than using a scraper.

[Floyd R Turbo]

If you used 40, you have to form a gap between the panes as it is not supposed to be used for flush bonding joints (so you have to put a few degrees of excess angle on the cut edge of the joint) and then fill the gap, then wet sand out the excess, then polish. Then if you want to completely avoid bubbles in the joint, after you mix the 40 and before it starts to set, you have to centrifuge it or put it in a vacuum chamber to get all the bubbles to rise to the surface.

40 is not easy to use and make it look professional. Also if you doin't know what you're doing, it will look great when you get it all done but when you fill it with water, it can just fall apart (immediately or a few months down the road).

Solvent welds, on the other hand, you can tell they are good right away.

[paphater]

Yeah I know all about bubbles and 40. I was paranoid with my first tank so I poured small fillets of 40 and bubbles galore. How would you recommend to prep the edges?

[Floyd R Turbo]

For solvent weld?