[CyborgDroid]

Hi. I am new to laser cutting. I want to make a toothed acrylic box that will hold water. Can this be done simply by putting the box together and applying some acetone so the seams weld shut or will the space between the teeth be in issue? Most DIYs I have seen for fish tanks use tape instead of teeth but I want the bottom of the box to sit about 2 inches above the bottom of the walls so it would be sturdier and easier to assemble with a toothed design. Thank you.

[AlanC]

I haven't attempted to make a waterproof acrylic box, but if I did, I think I would try cyanoacrylate glue (AKA "Superglue", which is a brand of cyanoacrylate.)

[mondo50m]

Remember, you have to be careful of anything put in a fish tank. Toxic chemicals will kill fish very easily. There is a special silicone that can be obtained at any aquarium store that will not harm the fish at all. I have used it on many occasions to build my own filter systems for marine fish. Most silicone type adhesives contain ammonia, which is bad, bad, bad for fish. Go to the aquarium store and get the correct adhesive for fish tanks, please.

Milt

[AlanC]

Remember, you have to be careful of anything put in a fish tank. Toxic chemicals will kill fish very easily. There is a special silicone that can be obtained at any aquarium store that will not harm the fish at all. I have used it on many occasions to build my own filter systems for marine fish. Most silicone type adhesives contain ammonia, which is bad, bad, bad for fish. Go to the aquarium store and get the correct adhesive for fish tanks, please.

Milt

If the box is to be used as an aquarium, good advice to check with an aquarium store to be sure whatever used doesn't harm the fish.

My understanding is that acrylic aquariums are made using an acrylic adhesive. I know that Weld-on makes a good acrylic adhesive and I would go that route for something like an aquarium where you wanted to make sure it lasts. It's a thin adhesive that is applied with a small needle to the seams and it melts the acrylic together.

I have used cyanoacrylate for gluing smaller acrylic items, but not sure I would use it for an aquarium.

[kb0nly]

I have made acrylic tanks, not necessarily aquariums, but for water cooling on PC's and spindle motors, etc. The best way is to start with the right glue, first off, DONT use super glue, it will just cloud the acrylic and overall look like crap, trust me, i have done it in a pinch for temporary repairs but its crap.

Weld-On 4 is what i generally use, its widely available. The lower the number, for example Weld-On 3, the thinner viscosity it is. #3 will run around as fast as you can pour it, #4 is more water like in my opinion, and if you need to fill a gap or dont want it to run then i have another can thats i believe #16 or #12, i forget what it is as i don't use it very often and its not close enough to grab it and check.

Your best bet for the design you want is to make a toothed design like you said, then use the thicker Weld-On to make sure all the seams are filled and sealed. Acrylic and Weld-On is what most of the fish tank places i have seen use, so i don't see why you would want to substitute in that regard!

[gfacer]

Uhm, no, use the silicone. Weld on for laser cuts might be OK if the acrylic is cast, but the tooth Pattern should make the silicone ok. If you do want to weld, skip the tooth pattern and scrape the edges instead to remove the glossy edge.

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[kb0nly]

I use Weld-On on acrylic all the time, perfect bond every time, not sure why your saying stay away from it. Silicone don't work for crap, i fought a fish tank for years that kept leaking over and over where it had silicone, the last time it was drained and cleaned applied some Weld-On 4 to the seam and thats been there for 5 years now, no more leaking every six months.

Silicone is ok for showers and tubs and sinks, and plumbers that can't cut a straight line, but its not a good adhesive for acrylic, to seal up a spot maybe, if you sand and prep the spot, even then the manufacturers i spoke with on the subject said that silicones adhesion rate to acrylic is a SURFACE BOND only. In other words put any pressure on it and its no better then a suction cup, it will fail at some point. Weld-On actually melts the two pieces together, you can do the same thing with MEK or even good quality acetone but the Weld-On is quicker to bond from my experience.

The tooth pattern idea i think is good because he wants a raised floor with the sides going down past, generally you would either have the floor supported by another structure to raise the tank or put in reinforcements like cross pieces under it. But i don't see silicone holding in that application because it would be lateral stress on the silicone with the weight of the water pushing outward on the sides, if it was only downward force then yes it would probably be ok but not as the primary fastening method for the sides.

Anyway, opinions are like bungholes, everyone has one, and thats my experiences and opinion on silicone and acrylic. Wrong glue for the wrong job. You also don't need to scrape the glossy edge to weld, i do it all the time, no issue.

[gfacer]

Great, you use cast then. Not everyone would.

If the toothed box holds together but leaks, silicone will seal the leaks.... It is, as you pointed out, not a good glue for acrylic, just a sealant.

Scraping off the gloss from the laser is always a good idea, not least is you can try to take off the tapered edge the laser makes, and the glued lasered edge will "craze" if extruded. Yes, you don't always have an issue, but it's still best practice....although doesn't work for a toothed design something maybe moot.

To the OP, make sure you calculate how thick you need for the size and depth of the tank.

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[CyborgDroid]

Thanks guys. I want to build a small box that can hold hot water (about 50C or 122F) without affecting the seam's integrity. design will be about 6x6x8 with the water residing in the 6x6x6 upper portion. I thought of using a pre-made ice bucket to increase thermal retention of the hot water since it has double walled acrylic with an air gap but making them myself will look better if I am able to sell them. I need the space underneath so attaching something to an ice bucket wouldn't look so good as if it was just one piece. And I can always engrave a brand or instructions on the box too, as opposed to a round ice bucket. I only have access to a flat laser cutter/engraver, not a round one. Is there any kind of insulation material that I could use on the acrylic (inside or outside) to retain the heat?

[mondo50m]

Ok, guys. I did not say not to use anything that you want. Normal silicone contains ammonia....as I stated....do not use it. It will kill the fish. Ammonia is the death of tropical and marine aquariums. Just a fact!.. I have had many marine fish tanks and they are mainly bonded with a 'non ammonia' silicone made specifically for sealing fish tanks and the special filters that are needed. You what you desire. I also use weld on for acrylic. But not in my fish tanks. Have a good day and enjoy. I am very sorry that I have an opinion reflecting about 40 years of marine aquarium experience. I will say no more.

Milt

[kb0nly]

Thanks guys. I want to build a small box that can hold hot water (about 50C or 122F) without affecting the seam's integrity. design will be about 6x6x8 with the water residing in the 6x6x6 upper portion. I thought of using a pre-made ice bucket to increase thermal retention of the hot water since it has double walled acrylic with an air gap but making them myself will look better if I am able to sell them. I need the space underneath so attaching something to an ice bucket wouldn't look so good as if it was just one piece. And I can always engrave a brand or instructions on the box too, as opposed to a round ice bucket. I only have access to a flat laser cutter/engraver, not a round one. Is there any kind of insulation material that I could use on the acrylic (inside or outside) to retain the heat?

If your only building it to then insulate it why build it? I'm not saying don't but you have me curious now. What would the capacity need to be? For example a five gallon bucket wrapped in a layer of insulation would hold more heat then an acrylic tank wrapped up... But to answer your question you could use just about any type of insulation around it if thats what you wanted.

[mountaindew]

For holding water cast or extruded acrylic will work for your application.
You don't want to use a laser to cut the bonded edges. This will cause an internal stress and result in weak or failure of bonded edge. called "crazing "
Best way to make an acrylic box is with sized panels made on a large flat router table. bonded with a weld on 3 or 4 adhesive.
I have written a very good tutorial on this subject to get good results and with care and practice make an almost flawless seam that is strong and professional.
making a number of acrylic tanks over 20 years and most still in use . Not a cheap material to work with btw
Basic Acrylic Fabrication
Use to have pictures looks like the links are broken now. Also some threads around here on acrylic fab I have done.
Good luck

[CyborgDroid]

Thanks for your response MountainDew. Is it possible to repost the pictures on your DIY thread? They are not showing up.

[mountaindew]

I will be working to fix this asap

[Kabomid]

I use Weld-On on acrylic all the time, perfect bond every time, not sure why your saying stay away from it. Silicone don't work for crap, i fought a fish tank for years that kept leaking over and over where it had silicone, the last time it was drained and cleaned applied some Weld-On 4 to the seam and thats been there for 5 years now, no more leaking every six months.

Silicone is ok for showers and tubs and sinks, and plumbers that can't cut a straight line, but its not a good adhesive for acrylic, to seal up a spot maybe, if you sand and prep the spot, even then the manufacturers i spoke with on the subject said that silicones adhesion rate to acrylic is a SURFACE BOND only. In other words put any pressure on it and its no better then a suction cup, it will fail at some point. Weld-On actually melts the two pieces together, you can do the same thing with MEK or even good quality acetone but the Weld-On is quicker to bond from my experience.

The tooth pattern idea i think is good because he wants a raised floor with the sides going down past, generally you would either have the floor supported by another structure to raise the tank or put in reinforcements like cross pieces under it. But i don't see silicone holding in that application because it would be lateral stress on the silicone with the weight of the water pushing outward on the sides, if it was only downward force then yes it would probably be ok but not as the primary fastening method for the sides.

Anyway, opinions are like bungholes, everyone has one, and thats my experiences and opinion on silicone and acrylic. Wrong glue for the wrong job. You also don't need to scrape the glossy edge to weld, i do it all the time, no issue.

Just to help you understand silicon glue more in detail.
Dried silicon leaves a oil residue behind and silicone can not make a good bond or seal on any oil surface.

So in the case like a aquarium repair it is very important to scratch, sand down and alcohol wipe down the area you want to fix. Even if you damage the glass with light scratches it's fine. Mostly going to be under the glued area and out of sight.

If there is any residue on the surface you want to apply silicon to even non visible small amounts, the silicon would not last.

Aslong as surface is completely cleaned from all residue the bond would be fine.

I myself struggled a long time with my 1 000 liter aquarium
That holds 1 ton of water mass and I've fixed it very well stil holding 2 years later