Acrylic fabrication questions? I can help!

[camaroboy8691]

this is probably the worse , its kind of confusing , but the very top is the bottom peice ,and then the 2 sides joined , its confusing becuase of the amount of solvent that came out of the joint and bubbled on the side

<a href="http://www.flickr.com/photos/91708975@N06/8327939826/" title="IMG_1764 by 225digger, on Flickr"><img src="http://farm9.staticflickr.com/8080/8327939826_44b796d465.jpg" width="500" height="375" alt="IMG_1764"></a>

 

[camaroboy8691]

anyways , lay it on me , im not worried about the bubbles if they are fine becuase it will be behind a wall and never seen

i still would like to do 1/2x 1/2 angles on the inside with maybe that weldon 16 just to be safe .

 

[peppie]

The majority of the seams look fine, a few small bubbles. No biggie
That last pic........
Looks like you welded the bottom to the sides with the bottom sitting on top of them.

 

[camaroboy8691]

That last pic........
Looks like you welded the bottom to the sides with the bottom sitting on top of them.

correct , i was contemplating on how to do it and figured it would be best to lay the bottom on top of the sides to bond it , i was thinking there would be to much wieght if i did it the other way around this stuff isnt light , i think 1 sheet is around 300lbs , so just all the sides is probably around 600lbs

 

[Floyd R Turbo]

Just a few questions that might explain why the bubbles might be there:

1) did you blow the joint out with compressed air then canned air (deionized air) before running the solvent?

2) did you glue on foam?

3) Did you use the pins method or just capillary action?

4) Did you leave a lip on the edge to be flush trimmed off afterwards? It looks like all your panels are cut for finished dimensions.

All in all I would say that the joints will probably be OK, they just don't look pretty. And I would never bond a bottom/top panel on that way - you always bond a panel with the joint at the bottom, not on top.

 

[camaroboy8691]

Just a few questions that might explain why the bubbles might be there:

1) did you blow the joint out with compressed air then canned air (deionized air) before running the solvent? i used shop air which is ran trhough a drier system i have at my shop , after that i clean with denatured alky and then let air dry for 10 mins

2) did you glue on foam? no foam , the surface i have is pretty flat and i didnt see the need for it when i was setting panels up , i know its a no no but just the size and weight of the panels i just dont think it was needed

3) Did you use the pins method or just capillary action? i used .014 pins let soak for 30-45 seconds before pulling them , you can see in the one pic it really pushed out the melted acrylic

4) Did you leave a lip on the edge to be flush trimmed off afterwards? It looks like all your panels are cut for finished dimensions. yes there is a lip , some places its only a 1/4" on the one end tho there is 3/4" but i do have plenty to trim

All in all I would say that the joints will probably be OK, they just don't look pretty. And I would never bond a bottom/top panel on that way - you always bond a panel with the joint at the bottom, not on top.

it deffenitly aint pretty , but its for me and as long as it all holds together im fine with it the front and one end i did take extra care to tape off and stuff becuase only 2 sides will be seen , the back and other end will get panted black , i still need to bond the top panel on the tank , maybe ill do that one with the sides on top . but i dont think i will, i really contemplated doing the bottom with the sides on top , but it was the wieght i was affrad to lift it all up and then slide it under , like i said , 1 4x8 sheet of this is like 300lbs , its not light

ill never make one of these again thats for darn sure ill stick with metal working


i would like to add some acrylic strips to the inside like gussets , where can i get pre cut gussets ? looking for maybe like 1/2x1/2 angles

 

[Floyd R Turbo]

Ok, I didn't see the lips on the pics - I wasn't looking at them right LOL.

I asked about the air blowing because bubbles can be caused by air attaching to dust particles in the joint. In this case I think you should have blown after the alcohol wipe. I always use compressed air on both faces of the joint, then wipe with alcohol, position the joint, insert pins, then blow the joint with canned/deionized air right before you run the solvent. After you wipe with alcohol, you need to blow again. DN alc gets rid of grease/fingerprints/etc but usually the rag you use no matter how lint free it is, will leave dust particles behind.

I hear what you're saying as far as weight goes. But that's still the preferred way to do it. Not saying there's not more than one way to skin a cat. The biggest problem with bonding the bottom panel on top like you did is that the weight of the panel will cause it to sag in the middle, resulting in a possible gaps around the edge of the joint, which invite air to intrude on the joint as the solvent dries.

Also you should have bonded the top euro on first. One reason is related to the above sagging issue - with the euro on bottom in position to bond, the bottom panel which is now on top will sag in the middle and cause the panels to flare out, and you will have problems getting the joint to be flush all the way around. It is difficult to support the bottom panel from the inside to prevent this sagging, because you might need a way to adjust the height of the brace when setting up the joint for solvent. Not impossible - just not simple.

If you put the top euro on first, then the weight/flare issue is not as bad, because material has been cut out, and you can easily access the interior of the tank to adjust a center support brace.

Also with the bottom on first, you create a cavity in the middle that is difficult to ventilate, meaning increased cure time.

As for the gussets, you can probably get them cut for you by TAP plastics or someplace like that. Probably not a bad idea for the bottom joint, considering all the bubbles. Remember that this will mean an increase in your overall curing time before you can put water in it. I would not hesitate to wait a full 4 weeks before putting water in.

 

[overflowin]

so here's what i'm up against. I recently picked up an 84*30*37.5 acrylic tank, with the knowledge that as it sits, it is probably a time bomb. the tank looks to be home built, made from 3/4" material. there's no paper left on it, so thats all i know about the acrylic... the end panels, however, are half inch black acrylic, and poorly cut/prepped. I have some pictures, i will post them in a bit.

i think i have 3 options... completely disassemble the tank and reclaim as much of the material as possible, cut the bottom 12" off, prep the edges and re-attach the bottom, or lastly, build an epoxy coated wood support structure and put it in wall.

any ideas?

 

[camaroboy8691]

As for the gussets, you can probably get them cut for you by TAP plastics or someplace like that. Probably not a bad idea for the bottom joint, considering all the bubbles. Remember that this will mean an increase in your overall curing time before you can put water in it. I would not hesitate to wait a full 4 weeks before putting water in.

for the gussets would weldon 16 be the better glue to use since it is thicker it should help fill any voids there may be right ?

 

[Floyd R Turbo]

WO16 is not a void filler, it dries up to the same "profile" as WO3. It might work OK here, but #40 would really be better, or just #3 or 4 as long as your gussets are touching both panels. Remember that you will have to round off the inside corner of the gussets due to the fillet created by bonging the panels. Also you are not really going for "sealing" the joint so much as you are reinforcing the joint, so you should not need to worry much about full contact all the way around. Your joints are probably water tight but the question in your mind is more like are they going to be strong enough, which they probably are, but better safe than sorry.

 

[peppie]

Can anyone recommend a source for Polycast, or Plexiglas-G
In the Washington, Oregon State.
My online search is not going so well

 

[Floyd R Turbo]

http://www.sabicpolymershapes.com/polyshapes/PShapes/branchlocator/branchus.jsp

 

[peppie]

Thanks for the quick reply Turbo
I noticed in their product line that it was Plexiglas-GM and NOT Plexiglas-G what is the difference ?
Also they sold Polycast-SAR is this the correct material for Display Tanks. I have never seen it labeled, in this way.
There must be a reason for the letters that follow the Polycast, or Plexiglas

 

[Floyd R Turbo]

Yeah I think that is their internal numbering system. IIRC, Plexiglas-GM is cell cast but whenever you talk to them (or any rep for any reseller, for that matter) you HAVE to reiterate over and over that you want Arkema Brand (that's the Plexiglas parent company) Cell Cast with the printed mask, G grade. That is the definitive way to ask for it. They also carry a generic cell cast from Arkema that has a plain mask (called P-MAX or PMACS) which is meant to compete price wise with import cast material and this is good for sumps, frag tanks, etc, and James has commented on this as well that after much research into this product's manufacturing that he personally would not recommend it's use for display tanks. So watch out for that.

Polycast, same drill. Except I don't know their numbering system for Polycast.

 

[rohny]

Hello

Im want to have a 120cm (47,24") length 80cm (31,5") wide and 80cm (31,5") high tank made in acrylic. I have been talking with varius vendors from Kina. My company buy a lot of stone and glass from over there so shipping should be cheap (combined with stone and glass)

My mail conserne is thickness and type of acrylic. One vendor wanted to make it out of 30mm acrylic (1 1/8") and another 19mm (3/4") The price difference was alos by a magnetude of ten. 4500$ for the 30mm 400$ for the 19mm. Im also trying to get more quotes, but what thickness do you recomend and what type of acrylic.

Thx

 

[Phixer]

31.5" tall. Id use 1" thick material because I dont like bowing. Use cell cast acrylic i.e Spartech, Polycast, Acrylite GP , Plexiglass or Reynolds. Everything else Ive seen is junk.

 

[overflowin]

ok, i finally found my usb cable. here are the pics...

this is on the end of the tank, where the face meets the black end piece. it looks to me like it was a sloppy table saw cut, or possibly a router mishap. either way it left a void you can see from this angle.

this is that same void, viewed through the 3/4" face. i stuck a pencil in to show the depth of the void.

there are 1/2" x 1/2" gussets in the corners, but i'm not sure of their integrity. there are a few spots where the gussets are attached that just look scary to me. like this spot.

I realize the tank isn't usable as it is, and i knew that when i bought it. i am now trying to make a decision on what i'm gonna do with it. from where i stand, there are 3 options...

disassemble and start from scratch, using as much material as possible from this tank.

cut the bottom off, make the tank about a foot shorter (current dimensions are 84l*30w*37.5t) to bring it closer to a reasonable size for the 3/4" material.

or lastly, leave it as it is, repair the seams and build it into a wooden structure to reinforce it and put it in-wall.

I picked this tank up pretty cheap. another reefer had gotten screwed on it and was stuck with it. i figured i could help him out and get it off his hands, and then make something happen with it. I'd be interested to see what the experts here think about my ideas, or any ideas of their own they wanna share.

thanks
Donnie

 

[Floyd R Turbo]

I would cut it all apart and re-use no existing seams. That work is so poor, I can't imagine why anyone thought it was not scrap from the get go.

The problem with re-using acrylic that has already been used is that

1) you have no paper to allow the material to easily slide across a router table/table saw (but you can buy masking and re-mask it)

2) It it scratched to heck (but you can re-finish it)

3) The material may have an inherent warp/bow to it, since it has been bonded, possibly held & absorbed water (the water will leech back out over a few months, and the material once cut apart and laid flat may un-warp)

I would say it would be a nice project to mess around with considering you got the material cheap, but those 3 steps above are a lot of work. Time is money and you would save a lot of time by getting new material and starting from scratch. But it is what it is, right? You will learn a lot about working with acrylic by tearing down this tank and building it right - and you can brag about it LOL

 

[peppie]

Re-using acrylic from a cut up tank is a nightmare!!
I have done it. I will never do it again!
Once you cut the tank up, the acrylic will be bowed and twisted. It is very difficult to get a straight square edge that is acceptable for a good welded seam.
Can it be done? Yep.
Is it worth the time involved? IMO, NO

 

[peppie]

Re-using acrylic from a cut up tank is a nightmare!!
I have done it. I will never do it again!
Once you cut the tank up, the acrylic will be bowed and twisted. It is very difficult to get a straight square edge that is acceptable for a good welded seam.
Can it be done? Yep.
Is it worth the time involved? IMO, NO