Acrylic Fabrication Q & A

[Lowell Lemon]

It's taken a few weeks, but finally made it through this entire thread - thank you to all who have contributed to this great resource!

My question is on laminating acrylic. I'm about to start my second acrylic display and system (the first one is about 10yrs old now), but I'm planning on this being a bare bottom. I was thinking of using 1/8 abs sheet as a bottom and back "cover" with the textured side showing. Was wondering if there is a good way to laminate that to the acrylic bottom and wall? The size of the display will be 60"w 22"d 24"h and I'll use 3/4" for front/back/sides with 1/2" top and bottom.

There are laminating cements that are available or you can use solvent starting on one end and slowly lowering the ABS as you fill the leading ebge with solvent. Any air space may allow the ABS to "bubble" as water is absorbed later. ABS bonds with the same solvents as Acrylic.

 

[GAreef]

There are laminating cements that are available or you can use solvent starting on one end and slowly lowering the ABS as you fill the leading ebge with solvent. Any air space may allow the ABS to "bubble" as water is absorbed later. ABS bonds with the same solvents as Acrylic.

Thank you for the help! Is that laminating cement a WO product?

 

[Lowell Lemon]

Thank you for the help! Is that laminating cement a WO product?

No I think Tap Plastics sells some formula for that purpose.

 

[JoelATX]

Joint test question. I searched for about an hour and couldn't find an answer.
I used some scrap 3/8" acrylic to make a tank (65 gallons, I think) including an AIO filter.
36 wide x 22 deep x 18 tall. Bottom is 3/8." Euro brace on top made from 2" strips of the 3/8" acrylic.
Bowing is almost none.
I had some gluing trouble, on the front bottom and back side. I re-enforced along the bottom with 3/8" square strips of acrylic.
How many days filled with water would be a good test?

 

[lapin]

My Ipinion
First let it cure for a week or 2. You do not want the acrylic to absorb water at a different rate than the seams.
Once cured, 1 day full of water will let you know if going to leak.
Will it fail? only time will tell. Just depends on the quatlity of the acrylic and how well the seams were bonded.

 

[JoelATX]

The main seams are 3 weeks old, all the AIO baffles are from Saturday morning. I guess I'll drain it for the week.

 

[Turbo's Aquatics]

3 weeks cure time for the bonds on 3/8" should be adequate. You can fill it for a leak test sooner than that - bond strength is nearly 100% at 72 hours, it's the absorbtion rates that do not follow that same time frame. So fill it, check for pinhole leaks/etc, then if all good drain it. If you're going to have a catastrophic seam failure because of an inherent problem with a particular seam or your technique, it's likely to happen right away.

It's still good practice to allow the full cure time to do a longer-term strength test (like the 24 hour test).

Euro brace on top made from 2" strips of the 3/8" acrylic.

The problem with strip braces and acrylic is that acrylic, unlike glass, does not respond to stress the same way. Stress focuses on sharp corners, so as the material in under long-term constant pressure when it's full, the highest probability of failure will be where the strip brace meets the end panel. Did you make he brace a full perimeter brace, or just along the front and back?

Pics?

I had some gluing trouble, on the front bottom and back side. I re-enforced along the bottom with 3/8" square strips of acrylic.

Should be good

 

[GAreef]

I built my current 60x22x22 acrylic tank with 3/4 front/sides, 1/2 top and bottom with 3 cutout openings in the top. The tank as been great for 10 years without any sign of bowing when I lay a 4' level across the front. But I really hate those 3 openings lol. Such a pain to work around. I'm about to start a new build (same dimensions) and am wondering if I use 3/4 for the top if I could get away with any front to back cross members? Maybe something like one large opening with 4-4.5" perimeter?

 

[lapin]

I built my current 60x22x22 acrylic tank with 3/4 front/sides, 1/2 top and bottom with 3 cutout openings in the top. The tank as been great for 10 years without any sign of bowing when I lay a 4' level across the front. But I really hate those 3 openings lol. Such a pain to work around. I'm about to start a new build (same dimensions) and am wondering if I use 3/4 for the top if I could get away with any front to back cross members? Maybe something like one large opening with 4-4.5" perimeter?

I have 4 openings on my tank. I think they build character. *-"

 

[GAreef]

I have 4 openings on my tank. I think they build character. *-"

I'm done with character

 

[TheHarold]

So I received a sump with a concerning amount of bubbles on a few seams, some going almost the full width of the joint.

I was wondering what the best approach would be to fix it. Should I squirt in some thin Weld-On from both sides? Should I also add additional bracing?

 

[lapin]

So I received a sump with a concerning amount of bubbles on a few seams, some going almost the full width of the joint.

I was wondering what the best approach would be to fix it. Should I squirt in some thin Weld-On from both sides? Should I also add additional beaching?

I would return it

 

[TheHarold]

I would return it

I liked the design a lot, and the cost of shipping the sump back and forth was too high. So im hoping to fix it and live with the small aesthetic stuff.

 

[Turbo's Aquatics]

I built my current 60x22x22 acrylic tank with 3/4 front/sides, 1/2 top and bottom with 3 cutout openings in the top. The tank as been great for 10 years without any sign of bowing when I lay a 4' level across the front. But I really hate those 3 openings lol. Such a pain to work around. I'm about to start a new build (same dimensions) and am wondering if I use 3/4 for the top if I could get away with any front to back cross members? Maybe something like one large opening with 4-4.5" perimeter?

Short answer is yes, you can get away with fewer openings with those specs

Generally, for a 22" tall tank, 1/2" is the minimum material thickness. Going to 3/4" virtually eliminates bowing at that height. If you wanted to deviate from the standard formula, which is a 3" perimeter and 6" crossbrace every 24", and change that to one in the middle instead, you could do something like increasing the perimeter to 4" and the center brace to 8".

But part of me thinks that is for 1/2" euro. If you went 3/4" euro - which means that not only are the walls overbuild, the euro would be as well - you could probably stretch that a bit more. Maybe 3" perimeter 6" centerbrace, maybe you could push it further but I would want to check more before giving you advice.

I don't think you will be able to do away with the center brace completely, but I could be wrong. No matter what, you will want to specify large radius sweeps on the euro

So I received a sump with a concerning amount of bubbles on a few seams, some going almost the full width of the joint.

I was wondering what the best approach would be to fix it. Should I squirt in some thin Weld-On from both sides? Should I also add additional bracing?

Pics would help. But generally, if it's a really bad weld, #16 or #33 will not do a whole lot. Adding gusset strips with #16/33 will do better. #40 is probably overkill but would really do the trick.

 

[Lowell Lemon]

You could use thicker acrylic for the body and go open top. Might cost a small fortune though.

 

[Turbo's Aquatics]

You could use thicker acrylic for the body and go open top. Might cost a small fortune though.

He's already (planning on) using 3/4" for both the body and top on a 22" tall tank (in case you missed that)

 

[TheHarold]

Pics would help. But generally, if it's a really bad weld, #16 or #33 will not do a whole lot. Adding gusset strips with #16/33 will do better. #40 is probably overkill but would really do the trick.

Im think a handful of areas qualify as "really bad".

I was hoping to just use some thin weld-on for the non-structural issues, just to make sure the baffles are watertight. And then potentially use gusset strips on the structural parts.

I dont suppose there is a way to remove excess solvent? Probably too hard to polish out all the drips up against corners.

@Antics sad right

 

[Lowell Lemon]

Im think a handful of areas qualify as "really bad".

I was hoping to just use some thin weld-on for the non-structural issues, just to make sure the baffles are watertight. And then potentially use gusset strips on the structural parts.

I dont suppose there is a way to remove excess solvent? Probably too hard to polish out all the drips up against corners.

@Antics sad right

Did you find any finger prints in those solvent welds....then we can prosecute. LOL! If you have any external seams like that the sump will leak for sure.

Attempting to remove the solvent weld drips is a waste of time. Sorry.

 

[TheHarold]

Did you find any finger prints in those solvent welds....then we can prosecute. LOL! If you have any external seams like that the sump will leak for sure.

Attempting to remove the solvent weld drips is a waste of time. Sorry.

Luckily the external seams are pretty good, just some bubbles here and there. It's the internal seams and all the routing that is poorly done.

Roger re solvent drips, Ill live with that.

Speaking of "prosecution", their resolution seems to be a 20% refund (They acknowledge the poor workmanship and say it is not representative of their typical quality). Dunno how I feel about that; I may or may not end up posting a review here on R2R. On one hand I dont want to potentially harm a business's reputation, but on the other, buyers shouldn't get quality like this.

 

[Turbo's Aquatics]

Looks like the gap was not shimmed tight or the sheet was not flat prior to pinning the joint = too much gap when you pull the pins. Plus no weight on top of joint. But if it's just an inner, non-structural baffle, you can run 16/33 on each side (maybe a few times) and that will prevent water from getting through the joint.

2 things going on here that I see. Something odd was done with the euro joint to get the solvent to show in that pattern. Typically you assemble the front/back/sides and then bond on the top panel with the top panel flat, so solvent can't really "wick up" in a pattern like that. My guess is that additional solvent (maybe 16, maybe 40) was added after the fact to reinforce the joint, possibly with the assembly tilted on the corner. Shouldn't be a problem if the joint is strong afterwards, just doesn't look pretty. Could also be bonded in high humidity, which turns the area of the bond (solvent/melted acrylic) white.

The flush trim and chamfer pass look like they were ran too fast, particularly the chamfer. When you push through the router too fast, you get those little pits. FYI you can get a roundover or chamfer bit and make another slower pass and clean that up very easily, but you might leave a few scratches on the acrylic if all the dust and bits are not cleaned off. Hard to not induce scratches on black when the paper is off. You could mask off the top with wide blue tape to avoid that