Floyd R Turbo
Either busy or sleeping
What's a beam saw? Laser beam? If so, then no.
Acrylic fabrication questions? I can help!
- Thread starter JohnL
- Start date
Floyd R Turbo
Either busy or sleeping
Essentially same as a panel saw or table saw, i.e. Spinning blade, so yes that's fine
Floyd R Turbo
Either busy or sleeping
To be honest I've seen tanks made by major manufacturers with such joints. But my answer is still yes, those will probably be an issue.
Did you cut the pieces to the exact final dimensions? This is how it appears. That means you did not leave a lip to be flush trimmed off after bonding. This lip allows for a fillet to form when you run the solvent, which prevents the air from sucking into the joint.
Also did you use the shim & pin method? Or did you just let the solvent wick into the joint via capillary action?
Did you use MDF with foam strips under the joint?
What is the material? I see plastic mask so I assume it's extruded?
You might be able to use this build, what are the dims and material thickness?
Did you cut the pieces to the exact final dimensions? This is how it appears. That means you did not leave a lip to be flush trimmed off after bonding. This lip allows for a fillet to form when you run the solvent, which prevents the air from sucking into the joint.
Also did you use the shim & pin method? Or did you just let the solvent wick into the joint via capillary action?
Did you use MDF with foam strips under the joint?
What is the material? I see plastic mask so I assume it's extruded?
You might be able to use this build, what are the dims and material thickness?
Did you cut the pieces to the exact final dimensions? -> Yes
Also did you use the shim & pin method? Or did you just let the solvent wick into the joint via capillary action? I've used pin method just for the first weld and I wasn't satisfied. After, I just let solvent via capillarity. But use no shim, only that : http://www.priceminister.com/offer/buy/181673286/presse-a-cadre-en-aluminium-3.html#sort=0&filter=20
Did you use MDF with foam strips under the joint? No, I've never heard that... What it is ?
What is the material? I see plastic mask so I assume it's extruded? It's cell cast acrylic
You might be able to use this build, what are the dims and material thickness?
It'll be sump like that :
lenght : 23,5'
Width : 14'
height : 14'
thickness : 0,23 in
Also did you use the shim & pin method? Or did you just let the solvent wick into the joint via capillary action? I've used pin method just for the first weld and I wasn't satisfied. After, I just let solvent via capillarity. But use no shim, only that : http://www.priceminister.com/offer/buy/181673286/presse-a-cadre-en-aluminium-3.html#sort=0&filter=20
Did you use MDF with foam strips under the joint? No, I've never heard that... What it is ?
What is the material? I see plastic mask so I assume it's extruded? It's cell cast acrylic
You might be able to use this build, what are the dims and material thickness?
It'll be sump like that :
lenght : 23,5'
Width : 14'
height : 14'
thickness : 0,23 in
Floyd R Turbo
Either busy or sleeping
Everything you need to know is in this thread.
You need to practice the pin method until you can get it right. It's easy.
Place 4" wide strips of MDF with camper shell foam on both sides under the material to level out the material and allow proper shimming & pinning.
When prepping material, do not cut to final dims. Ends will be final, but front/back should be longer to allow for material on both sides of joint so that when the solvent dries, it doesn't suck air into the joint. This is where your bubbles are coming from mainly. Then you can use a flush trim router bit to cut the lip off after the joint is cured. Similarly, the top and bottom will be longer on both dims for flush trim all around.
For you sump you may be ok. But I would probably add gussets just in case. A 1/4" x 1/2" strip should be fine, bonded in with weld-on 16. For 1/4" walls though I would add a strip across the top front edge and back edge, just for a little extra support. But that's me.
You need to practice the pin method until you can get it right. It's easy.
Place 4" wide strips of MDF with camper shell foam on both sides under the material to level out the material and allow proper shimming & pinning.
When prepping material, do not cut to final dims. Ends will be final, but front/back should be longer to allow for material on both sides of joint so that when the solvent dries, it doesn't suck air into the joint. This is where your bubbles are coming from mainly. Then you can use a flush trim router bit to cut the lip off after the joint is cured. Similarly, the top and bottom will be longer on both dims for flush trim all around.
For you sump you may be ok. But I would probably add gussets just in case. A 1/4" x 1/2" strip should be fine, bonded in with weld-on 16. For 1/4" walls though I would add a strip across the top front edge and back edge, just for a little extra support. But that's me.
Not trying to be an A**, just trying to help as I've learned a lot here to:
I notice in the first 3 pictures above, that most of the bubbles are on one side of the joint, that leads me to believe that either the panels are not plumb or the edge prep was not square.
while I don't use the foam (sounds like a good idea though), I place shims like every 3" or closer, and use a pin under each and every one. I also use several speed squares on each joint to keep things square. the pins method works great. I also had the same results the first time I did this, before I read this thread, using just capillary action on pieces that big.
I notice in the first 3 pictures above, that most of the bubbles are on one side of the joint, that leads me to believe that either the panels are not plumb or the edge prep was not square.
while I don't use the foam (sounds like a good idea though), I place shims like every 3" or closer, and use a pin under each and every one. I also use several speed squares on each joint to keep things square. the pins method works great. I also had the same results the first time I did this, before I read this thread, using just capillary action on pieces that big.
Floyd R Turbo
Either busy or sleeping
Any seam that looks bad. It's not meant to seal, just to support. So they don't have to be perfect. The bubbles weaken the seam, but if it holds water then it only needs a little extra strength
What brand of cell cast material? All cell cast materials are not created equal. Most brands don't glue worth crap to be honest, esp outside of *some* American, German, and Japanese materials. Most of the cell cast materials are formulated and polymerized so their molecular chain lengths are very long and very stable, however the adverse side effect is that because they are so stable - solvent doesn't get a good "bite" into them and your results are fairly typical.
There are only a handful of companies that make cell cast materials suitable for tank building. That is their molecular chain lengths are long enough to provide stability yet short enough to allow solubility - so they can be glued. The primary ones in the States are Polyone (formerly Polycast) and Plexi-Glas. Outside of the States, I'd look for Acrylite GS which is about the same as Plexi-Glas G/GM material.
Whenever you see folks sounding out against "import" materials - your results are the reason, I'm sorry to say. Even in the most experienced hands, most of these materials will provide sub-par results as compared to the other brands mentioned above.
With a little practice and getting better material, I'm sure you'll be more satisfied with your results
HTH,
James
P.S. hi all :wave:
Floyd R Turbo
Either busy or sleeping
Hey I just learned something new. It's that whole short-chain, long-chain thing that you've mentioned before James, but now I know a bit more as to the "why"...good to know, when giving a reason for why to only use certain products. Thanks James!
Chihuahua6
Premium Member
After moving I set my tank back up and noticed a faint hairline crack between the two bulkhead holes in the overflow. The crack doesn't go all the way down through the acrylic. It is only on the surface that I can feel it with my nail.
Can I run Weldon through the crack to seal since it's so faint it or is it necessary to also cover the bottom of the overflow with another sheet of acrylic? I will have to drill the holes in the acrylic sheet too so I'm hoping that just using the Weldon will be sufficient. I will only be able to glue a new piece from the outside too due to the lip around the overflow making it too small to fit the required sheet of acrylic from the inside.
Can I run Weldon through the crack to seal since it's so faint it or is it necessary to also cover the bottom of the overflow with another sheet of acrylic? I will have to drill the holes in the acrylic sheet too so I'm hoping that just using the Weldon will be sufficient. I will only be able to glue a new piece from the outside too due to the lip around the overflow making it too small to fit the required sheet of acrylic from the inside.
Last edited:
Floyd R Turbo
Either busy or sleeping
This doesn't sound good. Do you have a pic?
Chihuahua6
Premium Member
Just added the pic
Floyd R Turbo
Either busy or sleeping
Ok the good news is that the crack - unlike most people that post here about cracks - can't go any further. Normally the advice is "drill a hole at each end to stop the crack, then patch on both sides". You have built in holes on both sides of the crack.
The bad news is that you really do need a patch. The only way to get a solid watertight seal is to force something into the crack to expand it a bit (like T-pins, that I used to use for assembling model airplanes) so that you could get the solvent in there (weldon #3 or #4) enough to fill the crack without instantly bonding, give it 10-15 seconds, then pull them out. Or, you laminate both sides with a patch. The patch only really needs to cover the crack, but in this instance, you also would need to surround the hole because that's where the bulkhead is seated.
You might be able to get away with a patch on the outside only, given that this is in an overflow and depending on what you have the water level set to in the overflow, it might not be under a full water column of pressure.
But there is something you can do. Solvent in the crack as best you can. Laminate over the bottom and don't cut the holes yet. Then get yourself a jar of weld-on 40, mix up some, and pour this into the overflow. The stuff is like goo and it will self level. Let it cure for a few days, then drill it out. You might need to do a bit of sanding to get the bulkheads to seat/seal just right but that should do it.
Go to Dustin's thread here
http://www.reefcentral.com/forums/showthread.php?t=2075733
posts 1380 through 1414 for a similar issue (or at least a similar solution)
The bad news is that you really do need a patch. The only way to get a solid watertight seal is to force something into the crack to expand it a bit (like T-pins, that I used to use for assembling model airplanes) so that you could get the solvent in there (weldon #3 or #4) enough to fill the crack without instantly bonding, give it 10-15 seconds, then pull them out. Or, you laminate both sides with a patch. The patch only really needs to cover the crack, but in this instance, you also would need to surround the hole because that's where the bulkhead is seated.
You might be able to get away with a patch on the outside only, given that this is in an overflow and depending on what you have the water level set to in the overflow, it might not be under a full water column of pressure.
But there is something you can do. Solvent in the crack as best you can. Laminate over the bottom and don't cut the holes yet. Then get yourself a jar of weld-on 40, mix up some, and pour this into the overflow. The stuff is like goo and it will self level. Let it cure for a few days, then drill it out. You might need to do a bit of sanding to get the bulkheads to seat/seal just right but that should do it.
Go to Dustin's thread here
http://www.reefcentral.com/forums/showthread.php?t=2075733
posts 1380 through 1414 for a similar issue (or at least a similar solution)
Chihuahua6
Premium Member
Ok but there is one other challenge. The tank is set up with water now. I didn't know about the crack before I set it up. I just left the plumbing to do last as the bulkheads were already in place. I think I would need to drill out the patch before I glue.
Floyd R Turbo
Either busy or sleeping
Ooooh...yeah....that makes it more difficult!!!
I suppose you might be able to just patch one side, but you would have to use something like weld-on #16 or craftics #33 and somehow clamp it in place for long enough for it to cure (at least a few hours, 4 if you can stand it). Then put bulkheads back in and run with low volume flow / small water column so as to not put any undue pressure on them yet but yet still get flow in the system, then 24 hrs after bonding put the standpipe back in and off you go.
I think you could try squeezing solvent into the crack without trying to expand it, it's just not going to do anything structurally, it would just prevent leakage by water coming through the crack and then dripping out around the nut of the bulkhead. There's no saying that you will be able to fully seal the crack either
If you still wanted to do the WO40 you could rig something up to act as a dam around the holes after bonding the plate on. Something that wouldn't bond well to WO40, like a cardboard tube that you could easily cut out afterwards then use a drum sander drill bit to clean up the hole after the 40 is dry.
James might have a comment on anything he sees wrong with this suggestion...
I suppose you might be able to just patch one side, but you would have to use something like weld-on #16 or craftics #33 and somehow clamp it in place for long enough for it to cure (at least a few hours, 4 if you can stand it). Then put bulkheads back in and run with low volume flow / small water column so as to not put any undue pressure on them yet but yet still get flow in the system, then 24 hrs after bonding put the standpipe back in and off you go.
I think you could try squeezing solvent into the crack without trying to expand it, it's just not going to do anything structurally, it would just prevent leakage by water coming through the crack and then dripping out around the nut of the bulkhead. There's no saying that you will be able to fully seal the crack either
If you still wanted to do the WO40 you could rig something up to act as a dam around the holes after bonding the plate on. Something that wouldn't bond well to WO40, like a cardboard tube that you could easily cut out afterwards then use a drum sander drill bit to clean up the hole after the 40 is dry.
James might have a comment on anything he sees wrong with this suggestion...
Chihuahua6
Premium Member
Thanks Floyd. I'm thinking maybe I can send an acrylic tank builder a template of a patch to make for me. I was thinking that I can probably glue from the inside of the overflow if I make it an oval shape to fit over the overflow holes but not the entire inside of the overflow. This way I can get it inside.
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