karimwassef
Active member
New question. I'm fabricating a shallow box made of 1/4" acrylic. It held water just fine a month ago. After running with a strong light against it, it leaked... What gives?
Acrylic fabrication questions? I can help!
- Thread starter JohnL
- Start date
Floyd R Turbo
Either busy or sleeping
If you have a long solid (non-flexible) fence fixed in place and the edge that is against the fence is perfectly straight (and you have a good grip on the material and a smooth/slick surface), your rip should take off the same amount of material across the entire cut, because you have 2 sides that are parallel to each other, one on the bit and the other on the fence.
Need more details. overall dims? did you use the pins method for joints? Any visible air bubbles in joints? Where was the leak? pics?
karimwassef
Active member
It's 96" x 4" x 2" (said it's shallow). It was a light covering where the bottom face (96" x 4") was just underwater to get more light underwater.
I didn't check for air bubbles.
I just put them together and use the liquid acrylic glue (needle applicator). The joint was watertight when first installed.
I didn't check for air bubbles.
I just put them together and use the liquid acrylic glue (needle applicator). The joint was watertight when first installed.
karimwassef
Active member
Would it have been watertight and then degrade?
Floyd R Turbo
Either busy or sleeping
Could have been a slow leak. If it's meant to hold water out, then you can probably run multiple beads of Weld-on #16 to seal it up
Its possible itcould have absorbed moisture and tried to warp. At that long length, thin material, and being partially submerged, it could have warped enough to pop a weak joint.
Also how hot was the light this covered? This would have made the air much drier on the lamp side and contribute to the warping.
Have you ever set a flat piece of acrylic over the top of a tank? It warps easily from absorbing more moisture on one side. Even a piece of 1/4" with 1" tall reinforcing ribs warped beyond the ribs on only a little 20g tank top I built.
There is a clear plastic material said not to warp but I don't recall the name of it at the moment.
Karimwassef how long did the joints cure before being placed in the water? The joints need at least a few days to cure for strength.
Also how hot was the light this covered? This would have made the air much drier on the lamp side and contribute to the warping.
Have you ever set a flat piece of acrylic over the top of a tank? It warps easily from absorbing more moisture on one side. Even a piece of 1/4" with 1" tall reinforcing ribs warped beyond the ribs on only a little 20g tank top I built.
There is a clear plastic material said not to warp but I don't recall the name of it at the moment.
Karimwassef how long did the joints cure before being placed in the water? The joints need at least a few days to cure for strength.
karimwassef
Active member
It cured for a couple of days.
It's a rigid box - not sure how much it can warp.
Assuming that's the case, what's the solution?
Floyd R Turbo
Either busy or sleeping
how bad is it leaking?
What you can probably do is what I suggested. In addition to that, let the joint dry out thoroughly (put a fan on it, blow out the joints with compressed air, etc) then run the water-thin weld-on across all the joints and see where it wicks in. Let that dry for a few hours, then run a bead of weld-on #16 around the entire bottom joint, let that dry for 30 minutes, then tip it up on end and do 2 vertical seams, 30m, then the other 2 opposite end seams, 30m, then run repeat the whole process at least 1 more time. #16 isn't a gap filler, and it dries to a thin profile, but it's thick enough that a couple of built-up coats will seal up bad/leaky joints in an application such as this.
I've seen frag tanks at shows (MACNA in DSM/2011) that made me shiver - rough saw cuts bonded together with capillary action and then sealed with WO16 that looked like a disaster waiting to happen...but they held for at least the 3 day show, which completely stunned me. That being said, don't so that.
What you can probably do is what I suggested. In addition to that, let the joint dry out thoroughly (put a fan on it, blow out the joints with compressed air, etc) then run the water-thin weld-on across all the joints and see where it wicks in. Let that dry for a few hours, then run a bead of weld-on #16 around the entire bottom joint, let that dry for 30 minutes, then tip it up on end and do 2 vertical seams, 30m, then the other 2 opposite end seams, 30m, then run repeat the whole process at least 1 more time. #16 isn't a gap filler, and it dries to a thin profile, but it's thick enough that a couple of built-up coats will seal up bad/leaky joints in an application such as this.
I've seen frag tanks at shows (MACNA in DSM/2011) that made me shiver - rough saw cuts bonded together with capillary action and then sealed with WO16 that looked like a disaster waiting to happen...but they held for at least the 3 day show, which completely stunned me. That being said, don't so that.
adova
Premium Member
Patching question. A member on one of my local forums just posted a picture of his tank where the rear - vertical seam looks like it is separating. I do not have a lot of details, but he is getting recommendations to patch by putting in a square piece the length of the seam on the inside corner.
Any opinions on this as a repair? My gut reaction was to cut off the problem panel and replace it.
Shawn
Any opinions on this as a repair? My gut reaction was to cut off the problem panel and replace it.
Shawn
Floyd R Turbo
Either busy or sleeping
Repairing that by adding a gusset is the better way to go. cutting the panel off won't typically work well because it's really really hard to cut a panel off an existing tank and make all 4 of those edges perfectly planar so that you can bond a new piece on there.
Adding a gusset will make the joint stronger if it's done right, but to do that right, you have to empty the tank, preferably dry it out for a few weeks, then use weldon 40 and a triangle gusset that leaves a void (for the 40 to fill) and prop the tank up on blocks so that corner is facing down (creating a valley for the 40 to fill in). Real pain but works well.
Adding a gusset will make the joint stronger if it's done right, but to do that right, you have to empty the tank, preferably dry it out for a few weeks, then use weldon 40 and a triangle gusset that leaves a void (for the 40 to fill) and prop the tank up on blocks so that corner is facing down (creating a valley for the 40 to fill in). Real pain but works well.
skeeter_ca
Active member
Can you edge weld two pieces of acrylic and not have a visible seam or maybe almost invisible?
I am considering a very long build. 12"x12"x16'(feet). Using 1/2" cell cast acrylic I would like to edge weld 2 pieces of 96"x12" panels to make a 16' panel. What would be the best method for edge welding something like this?
I am considering a very long build. 12"x12"x16'(feet). Using 1/2" cell cast acrylic I would like to edge weld 2 pieces of 96"x12" panels to make a 16' panel. What would be the best method for edge welding something like this?
rickztahone
New member
Have you welded acrylic before?
skeeter_ca
Active member
yes, sumps, small projects, but nothing that large. Just wondering if it is possible, how is it done. I would imagine seamless edge welding will take some practice.
dattack
Active member
Weldon 40 or 42 with the edges cut 45 degree angle. Tape on one side and a lot of sanding and polishing afterwards
skeeter_ca
Active member
How much of the edge is beveled if say using 1/2" acrylic. Sounds like maybe you tape up the back side and fill the space between the two with Weldon 40/42. Let it cure then sand to level and polish. Is that about right? Any videos on this process or websites describing in detail? I was searching and couldn't find any.
sinisterreef
New member
How are you guys cutting eurobraces? I have read a 2" diameter for the corners is best. The only way I can think of is using a router jig of some kind. I'm not sure a jigsaw would produce good results unless you use a blade for fine finishing.
Floyd R Turbo
Either busy or sleeping
From what I've read, it's just a few degrees of bevel. I believe there is a link to a video recently in this thread, a few months back. It was a video made by Cyro/Acrylite I think
I would go 3" diameter (1.5" radius) minimum. This is what James/Acrylics recommends.
The manual method for me is this:
1) cut a hole in a piece of MDF with a standard hole saw
2) sand the hole so that it's as smooth and round as you can make it.
3) double-stick tape this to a piece of scrap 3/8" acrylic.
4) cut hole with a flush cutter
Now you have a hole template. If you happen to have a circle jig for your router, you can make a perfect hole with this as well.
Now:
1) Map out your eurobrace cut by tracing out the rectangle on the paper mask.
2) double-stick tape your hole template in one corner so that the 2 sides of the rectangle in the corner are just visible in the circle template.
3) cut out the hole
4) repeat 2 & 3 for the 3 other corners
5) take a strip of acrylic with a perfectly straight edge and double-stick tape this down to that it lines up with one of the trace lines from step 1 and it tangential with 2 of the holes you cut.
6) cut between the 2 holes using the strip as a fence
7) repeat 5 & 6 for the other 3 sides of the euro
That's it!
It can take a little practice to get things to line up just right when you're laying the strips down but this will get you very close to a perfect euro. Unless you're way off, you should be left with nice transitions into the corners, maybe a little bump, but as long as you avoid any sharp corners, this is a vast improvement over any other method short of CNC
There was a thread some years ago now, where a guy built almost this exact tank. He used WO 40 or 42, beveled the edges a few degrees (not 45!) then filled the gap. Lots of polishing but it was a nice joint afterward. He did a great job on the overall system build too. Sorry I don't recall his username.
Long story short: Yes it's possile[emoji106]
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