Acrylic fabrication questions? I can help!
- Thread starter JohnL
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rrg1974
New member
Thanks a lot.... I'm little nervous....
rrg1974
New member
I built my sump 36x18x16, but it's a sump and I wasn't too worried about bubbles, but now I have to. The acrylic I purchased was cut with very little saw marks and I'm finishing prepping, and it looks cert smooth. I'll practice with some scrap I got before.... Thanks for the info.
Hey guys, I am looking to build a small tank 18lx18wx20h. I want it rimless so i was thinking to go with 1/2" thickness. Could i do 3/8"? Its going to have a divider running in the back 4" off the back wall. I dont know if this would provide any support so i didnt take it into account with my calculations, but i figure id ask before i did something stupid
wastedtime
Member
With 20" of height I would definitely suggest 1/2" or maybe more. The divider will only help hold the 2 side panels together.. and I dont think provides structural rigidity.
really? 20" most people i have seen use 1/4 to 3/8 with eurobracing so i figured it wouldnt be terrible going up more. I made a sump 48x16x16 with 1/4 granted it was euro, crossed, and baffles everywhere so that accounted for more strength what size would you say?
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It will hold water, hope you dont mind a little bowing.
I am not a pro, but I would use 3/4 and rid yourself of the bowing look
rrg1974
New member
Hello guys, I need some opinions. Do you think I could go rimeless on a 46x23x23 1/2" plexy G acrylic tank?? I'm finally going to start my build it tomorrow, and I've being checking some 120 gal glass tanks and looks like the manufactures are using 3/8 glass. So another question. If acrylic is much stronger than glass, on a theory I could build this tank rimeless right? I'm also just afraid if it will bow too much. I also had the idea of using 2 long pieces of 1.5" by 46" going across the front and back panel to give some support for the long (46inc) pieces. So what do ou guys think? I'm just crazy?
yikes i was hoping that wasnt the answer. price jump point is expensive between the two different sheets. i am just surprised it needs that much acrylic thickness
based on what i was just told that i couldnt go rimless on a tank smaller than yours, i would say you need to brace yours
Yea , crazy... LOL
Your fears are correct it WILL BOW with out the proper bracing.
The width of the top bracing you speak of should be doubled, so it would be min 3'' all the way around, Eurobrace
That is my 2 cents.
The pros might jump in and correct me.
NEReef
New member
Hey i bought a used acrylic tank and the top bracing is cracked. I think the previous owners tried to carry it by the brace. So i assume i will need to cover these joints with acrylic strips to act like strapping? would i need to go over and under? Or just one way? Is a particular one better then another? Also the tank is all half inch so i am assuming again that i would to brace with 1/2" acrylic? The tank is 72x36x31 fyi.
Floyd R Turbo
Either busy or sleeping
Either way you cut it, you will have an 18" wide x 20" tall panel without some kind of middle baffle is what it sounds like. Therefore any tank calculator you would use 20H and 18W which gives rimless minimum thickness of 0.491 which bumps you over 1/2" (.472) material unless you use polycast. Add a euro and you can go to 3/8" (0.354) but 1/2" would be better with a 3/8" euro.
No friggin way. You would need 1.25" thickness according to the Cyro calculator and even that is going to bow over time without a brace. You can't compare glass and acrylic like that. Yeah it's stronger material but that does not directly translate when dealing with water as you are putting seams under pressure.
Floyd R Turbo
Either busy or sleeping
Hey i bought a used acrylic tank and the top bracing is cracked. I think the previous owners tried to carry it by the brace. So i assume i will need to cover these joints with acrylic strips to act like strapping? would i need to go over and under? Or just one way? Is a particular one better then another? Also the tank is all half inch so i am assuming again that i would to brace with 1/2" acrylic? The tank is 72x36x31 fyi.
Tank is likely cracked because the radius of the corners on the cutouts is zero. It should have been 2" radius to relieve the stress at these points. If it were me, I'd replace the top. Those cracks do all the way to the joint, and the only way to stop them from eventually continuing down the vertical panels is to stop the crack by drilling a hole at the end of the crack then sandwiching the cracked area with acrylic. With the crack to the corner like that it makes it more difficult. Not to mention that nay other parts of the top brace that aren't cracked will then be put back under stress and will eventually crack.
Personally I would not have bought a tank in that condition.
NEReef
New member
So it is in that bad of shape? I have never owned acrylic. I cant just get a brand new top and glue it right over the top? How difficuflt would it be to cut the top off and replace? Also there is a plastic place near me that builds acrylic display cases I could always take it to them they have all the professional tools. Can you explain why the crack will transfer down the front panel sorry but i am new to acrylics obviously.... Stress from the crack?? I just assumed it would be like wood (I have some woodworking background) and that if it was properly braced the new brace would handle the "load"/stress placed on it by the old crack.
Thank you this is what i was looking for. I didnt realize half inch was under actually .5 so my calculations were different. Thank you
Floyd R Turbo
Either busy or sleeping
here is another pic of the tank if that helps for reference
Woodworking somewhat translates. Acrylic when bonded is actually welded together with a solvent so the pieces become one. In most cases, the joint is actually stronger than the material, if you take 2 pieces and bond them, let them cure, and then try to break them you'll break the sheet not the joint. So a crack that has formed in the top sheet that reaches the joint can translate down into the back panel easily.
You can laminate a sheet right over the top of the existing top, and that might work OK but who knows for how long. You can brace on the inside across the crack also but if you don't stop the crack, it will eventually spread. If James was feeling up to it he might be able to respond better but he's staying off the forums for a while.
As far as taking it to a plastics shop, unless they work on aquariums I wouldn't trust them any more than a DIYer. Aquarium work is a specialized subset IMO and most acrylic shops don't know it well enough. It's not that easy to take the top off an existing tank and put a new one on correctly esp if you've never done it before, x2 with a tank this big.
NEReef
New member
Ok so i have a couple of questions i would like your input on.... 1.can i just make a jig and use a router to just remove the top??? Then glue/weld a new top on?? 2. Shouldnt a plastics shop be able to make the joint seamless tho?? I understand they might not have all the technical data on sizing etc but if i give them the tank and say glue/weld a 1/2" acrylite top of these dimensions on it with these cutouts..... isnt that joint universal whether its an aquarium or not??
