Acrylic fabrication questions? I can help!

Weldon 40 aquarium assembly

Weldon 40 aquarium assembly

Acrylics,

I was hoping you could answer a couple questions I have regarding acrylic aquarium assembly with Weldon 40.

1) How should the joints be prepared after cutting with a saw? I have read articles stating that both pieces of the joint need to be abraded using 240-400 grit sand paper. Is a hand held jointer edge suitable for the Weldon 40 to adhere to? This particular tank's sheet size and joint angle prohibits a bench jointer or router.

2) How much of a gap between the joining surfaces should be left to avoid a dry joint.

3) When assembling a rectangular aquarium. What is the best method for assembling the end panels to the front sheet?
Should I fix the end panels into a 90 degree jig, build a dam using aluminum tape then apply the Weldon 40. Allowing it to flow into the beveled joint.
Or
Should I poor the Weldon 40 into a dam on the horizontal sheet to be joined then move the vertical piece into position.

4) From my understanding Reynolds Polymer’s acrylic does not solvent weld well because of its high molecular weight. Is this true?

5) Assuming that I must use Weldon 40 with Reynolds’s acrylic to assemble the top and bottom of the aquarium to the sides. How do I keep the inside edge of the vertical sheets from resting on the horizontal sheet? Do I use acrylic spacers between joining surfaces underneath the 4 un-routered corners? Then place shims under the tank to ensure a proper gap? Before pouring the cement should I build a dam so it does not flow out of the joint?

I already have a vacuum chamber and vacuum pump to prepare bubble free Weldon 40. So I have no need for purchasing Weldon 42, which has a disadvantageous faster set time anyways.

On a side note, I have years of solvent welding experience building personal aquariums. I am looking to produce museum quality bonds so any additional pointers would be greatly appreciated.

I have plenty of scrap 1” thick acrylic to practice on just looking for some initial advice.
 
Last edited:
If you ask me (I know you didn't) but there should be no reason that whatever you're using isn't solvent weldable. I could be wrong here but Polycast has a very high mole weight and it is the choice of top manufacturers and James has said he solvent welds everything up to about 2" or so. So I guess why use WO40/42 when you know how good a solvent joint is right away vs. 40/42 where you don't know until you fill the tank and it doesn't fall apart. I seem to recall Reynolds being brought up somewhere in this thread but would have to search a bit for it...
 
Floyd,

Solvent welding certainly has its advantages.

Acrylics posted this on Page 33 of this thread regarding reynolds.

"Their tube is high mole weight so doesn't break down well to glue using solvents. The joints must be cast using 40/42."

Don't quote me but I recall Acrylics mentioning reynolds poor solvent capabilities a couple times in this thread.

On a side note.
If the joint is properly prepared before assembly with weldon 40 there is absolutely no reason it should fail.
 
Hi guys,

I have a quick acrylic fabrication question. Sorry if it sounds simple, but I was wondering how to "de-burr" my cuts that I make. I recently cut myself pretty badly on a sharp edge after removing a piece of cut acrylic from a milling machine. Is there a way to polish the edges to prevent this?

Thanks for the tips guys,

FB
 
What is the best drill bit or what would be the best way to put a hole in a piece of 1/8 wall acrylic tube.
I remember reading something on the lines of an altered spade bit but can't find the info on that.
What do you recommend?
 
Fishbulb2 said:
Hi guys,

I have a quick acrylic fabrication question. Sorry if it sounds simple, but I was wondering how to "de-burr" my cuts that I make. I recently cut myself pretty badly on a sharp edge after removing a piece of cut acrylic from a milling machine. Is there a way to polish the edges to prevent this?

Thanks for the tips guys,

FB
Click to expand...

edge scraper or router
 
Fishbulb2 said:
Hi guys,

I have a quick acrylic fabrication question. Sorry if it sounds simple, but I was wondering how to "de-burr" my cuts that I make. I recently cut myself pretty badly on a sharp edge after removing a piece of cut acrylic from a milling machine. Is there a way to polish the edges to prevent this?

Thanks for the tips guys,

FB
Click to expand...

If you're talking about the sharp edge that results from using a router or jointer, don't do anything to it until you're done bonding. You want that sharp edge to bond down, otherwise when you run your solvent and pull the pins it will promote air pulling into the joint. After you're all done with the build, then either use a 1/8" corner round or 45 degree chamfer bit, or just take a razor blade and run it down the edge about 3-5 times. The latter takes the edge of very nicely and easily.

As for cutting your hands...welcome to the club. Every day I come out of my garage with fresh cuts I didn't even know I had done. Move slowly, grip carefully, and learn from it when you don't.
 
Would you consider the pin method to be "far superior" in terms of welding methods?

I have seen some successful builds with simple capillary action, while the pin method seems so much more involved.

If you don't mind, what do you deem to be the advantages of one method over another?

I would like to fabricate my next large sump and would like to use the "best" approach.
 
Without a doubt, far superior, for several reasons.

The first and foremost is joint strength. The bond strength between the materials of a capillary joint (flush joint) vs a pins joints will not be the same. The joint strength of a pin set joint will be greater because a pinned joint allows each side of the joint longer contact time with the solvent, which allows the solvent to 'bite' into each piece. When the pins are pulled, the ooze that comes out is not solvent, it is dissolved acrylic from both sides which then cures into a solid piece. This results in a joint that typically is stronger than the adjacent material itself.

The second part is working time. You have literally zero room for error with a capilary joint. Once you run it, you had better get it in the right spot, and fast. A pin joint allows you a good 20 or maybe 30 seconds to adjust to the joint to perfect alignment before it starts to set to the point where you can't move it. A capillary joint will set nearly instantly.

Third is bubbles. A capillary joint will be very difficult to get bubble-free, and bubbles mean a weaker joint. Any imperfection in the finished edge can result in a bump or a divot for a bubble to form around. This can occur with a pinned joint too, but you can easily scoop out the bubbles and fill in the solvent before it sets (another reason why you want more working time)

There are more reasons but these are my top 3. I wouldn't do it any other way. I set 4" joints of 1/4" acrylic with the pins method, they (almost) always turn out perfect.
 
Without a doubt, far superior, for several reasons.

The first and foremost is joint strength. The bond strength between the materials of a capillary joint (flush joint) vs a pins joints will not be the same. The joint strength of a pin set joint will be greater because a pinned joint allows each side of the joint longer contact time with the solvent, which allows the solvent to 'bite' into each piece. When the pins are pulled, the ooze that comes out is not solvent, it is dissolved acrylic from both sides which then cures into a solid piece. This results in a joint that typically is stronger than the adjacent material itself.

The second part is working time. You have literally zero room for error with a capilary joint. Once you run it, you had better get it in the right spot, and fast. A pin joint allows you a good 20 or maybe 30 seconds to adjust to the joint to perfect alignment before it starts to set to the point where you can't move it. A capillary joint will set nearly instantly.

Third is bubbles. A capillary joint will be very difficult to get bubble-free, and bubbles mean a weaker joint. Any imperfection in the finished edge can result in a bump or a divot for a bubble to form around. This can occur with a pinned joint too, but you can easily scoop out the bubbles and fill in the solvent before it sets (another reason why you want more working time)

There are more reasons but these are my top 3. I wouldn't do it any other way. I set 4" joints of 1/4" acrylic with the pins method, they (almost) always turn out perfect.
 
Quick question, I noticed a few bubbles in the corner of my tank, being it's only 4 gal, I'm not worried about it to much, but since it's in the corner, where the most pressure will be, I was thinking about putting some weld-on 16 on the joint, just for peace of mind, it's in the back of the tank so looks aren't of concern, but I was wondering if putting weld-on over an already welded joint will cause any issues?
 
16 will stress the joint.
how big are the bubbles, what thickness material? And where in the seam is it.

Actually, the most pressure in a tank is at the bottom of the tank... bottom seam.
So if it's toward the top, if the bubbles arnt huge, I wouldn't worry about it.
 
Material is 1/2" plexiglass-G, bottom corner, goes up about 2 1/2"--3" theres some small bubbles in the other seams, but nothing serious, this is the worst seam,

seam2.jpg

seam3.jpg

seam4.jpg


and this is the other seam, not as bad,
seam.jpg
 
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