Acrylic fabrication questions? I can help!

Thanks Floyd.
I was thinking of starting with a 600 grit wet/dry. perhaps it's better to work backwards with this stuff and jump up over 1000 grit. or a buffing compound like you suggested. then see if the haze disappears.

Note to self: no more urchins in an acrylic tank!
 
Yes I would not start with 600 'cause you then have to take the 600 pattern all the way out. Start with 1500 and you might get lucky, if not step down to 1200 then 1000 etc
 
How to identify

How to identify

acrylic

I just got 3 sheets of 1/2" acrylic.....or something for free. I would like to make a 8'x2'x20"
first, should i be concerned about "what" it is?
i read somewhere of a test to tell if it is cast or not.
second, if i keep spans in the sump no more then 36"
last, if i cant identify........ what do i use to glue it with? as i would guess that different products use different glues

ps.... thank you for your expertise
 
i was browsing thru a thread the other day while at work, and chingchai had sold his old RIMLESS(no bracing at all) acrylic tank that was something like 66"x48x not sure how tall. i dont remember the exact dimensions b/c it was in mm not inches. the acrylic looked VERY thick.
 
James,

I'm going to build a tank with the following dimensions and material:

44 L x 20 W x 12 H

All Plex-G material

Walls 1/2"
Top and bottom 3/8"

Internal overflow box w/holes drilled on back wall

What size eurobrace could I get away with? I was originally planning on a 2" brace with 2" radius on each corner and no crossbrace. However I want lids as well so I was going to put another 2" brace in the middle. Will that be sufficient or could I get away with a smaller one?

Another question on lids. I recall reading somewhere in this thread that Polycarbonate does not warp, or at least not as bad as acrylic. Could you elaborate on this a little? I am not familiar with the proper material for solvent welding and fabrication techniques for Poly.

Thanks
 
Floyd R Turbo said:
James,

I'm going to build a tank with the following dimensions and material:

44 L x 20 W x 12 H

All Plex-G material

Walls 1/2"
Top and bottom 3/8"

Internal overflow box w/holes drilled on back wall

What size eurobrace could I get away with? I was originally planning on a 2" brace with 2" radius on each corner and no crossbrace. However I want lids as well so I was going to put another 2" brace in the middle. Will that be sufficient or could I get away with a smaller one?
Click to expand...
I think what you have above is a good plan :) Could you get away with smaller? yup, but.. you will be sacrificing structure and that's something I neither do nor advocate :)

Another question on lids. I recall reading somewhere in this thread that Polycarbonate does not warp, or at least not as bad as acrylic. Could you elaborate on this a little? I am not familiar with the proper material for solvent welding and fabrication techniques for Poly.
Click to expand...
Polycarb has a much higher moisture content so can't absorb enough to warp like acrylic, so it doesn't.. :) Pretty much any solvent for acrylic will work on polycarb, just not nearly as well.

PC is a *much* softer material. As such, it is "grabbier" and routers *will* simply pull it out of your hands if you mess up.

James
 
Yeah I know what that's like and can imagine it being much scarier if PC is grabbier that acrylic. What do you do then, besides being really really careful? Use jigs and flush cutters to prevent grabbing?
 
That's still going to bow quite a bit. To make it rimless and no bow at that LxH you'd probably have to go pretty thick, like 3/4" or 1" even. I'll leave the exact answer to James though...:)
 
Floyd R Turbo said:
Yeah I know what that's like and can imagine it being much scarier if PC is grabbier that acrylic. What do you do then, besides being really really careful? Use jigs and flush cutters to prevent grabbing?
Click to expand...
Yup, I can route "freehand" through up to about 1/2" PC without much issue, but anything above 1/4" can be problematic if something goes awry. And yes, PC is much scarier than acrylic in this regard.
Jigs and flush-cutters are pretty much where it's at for this material :)

Heavy Hittah said:
Quick question, if im looking to make a nano cubed tank, 24x24x12, should I use 3/8 inch so I don't have to euro brace?
Click to expand...
Personally, I'd use 3/4" acrylic. Even 1/2" will bow over time and you're not looking at a whole lot of material so should be relatively inexpensive :)

That said, making this small tank from glass would probably be cheaper.

James
 
James, since your talking PC, do you mind elaborating a little for me.
Ihave seen a few Sumps being made of this, and I like the looks of it.
Do you mind helping with the solvent question. You said any acrylic solvent will work, but will it hold structurally for a water holding container?

And what's your opinion on strength verses acrylic? Would the same thickness of PC equal that of Acrylic? Or does it require thicker or thinner material?
And would you personally have a PC sump,or do you prefer AC and why?

Thanks for all your information and helping me, as well as all the other priceless info you have shared
 
About storing sheets: I have always seen it stored flat. I assume this is to prevent warping. I know that any sheets I've stored leaning against the wall warp pretty quickly.

If I built a rack system that would hold sheets standing up on their long edge and held them tightly, would they still warp? I was thinking that I could take 2 sheets of 3/4" plywood and sandwiched them on either side of a bunch of sheets, then clamped them together, would this prevent warping?

My purpose here is to be able to stock full sheets without taking up all my space, as I have to drive 2 hours each way to get decent prices and I usually have them cut for me. I can easily store 1/2 sheets on a raised flat platform I made, but even that takes up a lot of space. If I clear the space, I can get a panel saw bwahahaha.
 
You might also think of MDF and not ply, so you don't have a texture,but also, it seems stiffer then ply. Just a thought.
And if the wall part of the rack is screwed and stiff then anything leaning against it should be fine. The 2nd layer sounds like good insurance!
 
dahenley said:
James, since your talking PC, do you mind elaborating a little for me.
Ihave seen a few Sumps being made of this, and I like the looks of it.
Do you mind helping with the solvent question. You said any acrylic solvent will work, but will it hold structurally for a water holding container?
Click to expand...
Yes and no. PC should be dried before gluing as the moisture content is so high - just tends to bubble. Drying is akin to annealing. long time, low heat, unmasked.. not practical for the most part.

Most fabricators use methylene chloride to glue PC as well as acrylic. However, tetrahydrafuran (THF) can also be use about as effectively as methylene chloride. THF is the primary ingredient in PVC pipe cement.
Weld-on 40/42 can also be used, but in any case; if you're going to be gluing for a tank - would strongly advise drying the material first.

That said, I can't say I've *ever* seen someone make a sump out of polycarbonate. I know it's been done, I've just never seen it and can't believe it would look any better than acrylic nor be nearly as strong.

And what's your opinion on strength verses acrylic? Would the same thickness of PC equal that of Acrylic? Or does it require thicker or thinner material?
Click to expand...
Would need to be thicker to keep deflection down and for increased gluing surface as the bonds are not as strong as acrylic bonds. Since PC is softer, it will want to warp more with load.

Just as acrylic is softer than glass, PC is softer than acrylic. Adjust thicknesses accordingly.

And would you personally have a PC sump,or do you prefer AC and why?
Click to expand...
No, I wouldn't. I can't think of a single good reason to use PC over acrylic for our applications, not one.

Floyd R Turbo said:
About storing sheets: I have always seen it stored flat. I assume this is to prevent warping. I know that any sheets I've stored leaning against the wall warp pretty quickly.

If I built a rack system that would hold sheets standing up on their long edge and held them tightly, would they still warp? I was thinking that I could take 2 sheets of 3/4" plywood and sandwiched them on either side of a bunch of sheets, then clamped them together, would this prevent warping?
Click to expand...
it'll help but if the wood warps, so will the acrylic. And considering one side of the wood will be exposed - I would suspect it'll grow and become convex over time.

HTH,
James
 
Yep, I was going to brace the outside of the plywood sheets with a 2x4 frame (with cross pieces to keep it from warping) and secure one side to flat 2x4s on the floor, put the sheets on the flat 2x4s, and the put the other plywood/2x4 piece against the acrylic and clamp them together. Sounds like I should be able to do that. Just takes some power tool work. Which I don't mind!
 
building new refuge

building new refuge

i just chipped my 75 gal glass tank i was using in my build. So now its buy another or use the acrylic baff i made to their best use by building the outer tank as well. The tank would be 48"x20"x18" with multiple 1/4" baff going across, the most open spot will be 20"x20"x17". So my ? is how thick would the outside and bottom need to be?? Any advise would be great...
 
I am thinking about building a 120 tall. 48 x 18 x 30 H. What thickness of material should I use for this, and what size cutouts would I want to have?
 
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