Acrylic fabrication questions? I can help!
- Thread starter JohnL
- Start date
if you're only going to have a perimeter flange, how are you going to glue your overflow to it? got a drawing?
huh? do you mean slots?
why would you do that?
James
Floyd R Turbo
Either busy or sleeping
if using the Intertape paper tape. Slam the stuck pieces on a flat surface, the tape will break free.
James
James, you are full of all kinds of useful tidbits of information. This is one I would never have thought of. The first time I tried it, I was like "how in the f--- does that work?" It just makes me laugh when I've got a template stuck down hard and I just throw in on my router table, and it literally pops off and flies up in the air. Just to think about all that time wasted trying to get one corner separated with a razor blade so I could get a paint scraper in there to pry the piece apart, when all I had to do was chuck it on something!!
I noticed that if you slam piece down perfectly flat with your hand in contact the whole time, they do not come apart. You have to let the pieces go when you slam them down or drop them firmly (not sure how else to describe it) so that one corner or edge hits before the other (maybe as little as a 1 degree angle) and this appears to induce enough "flex" throughout the pieces that it just pops the tape right off. It still blows my mind how easy it is.
LMAO!!
:beer:
I fabricated my own 50 gallon tank about 1 year go using 5/8 cell cast plexiglass. I notice about two or three months after filling the tanks I started getting the hairline cracking only on the corners that I routed round edges on. I can not feel the cracks on the inside or outside of the tank. What causes this type of cracking? If I sand the tank down and re-polish it will they return?
Floyd R Turbo
Either busy or sleeping
Looks like crazing to me. Nothing you can do to fix that. Looks to me like you put a big round on that corner, which makes that area weaker. At most I put a 1/8" corner round on tanks, if even that. Yours looks like a 1/4" round. That's a lot of material in an area that needs strength. Also did you polish it mechanically or flame polish?
What are the tank dims?
Also 5/8" is not a standard thickness for Plexiglas. Is it "G" (with the printed mask) or was there no print on the mask? If it actually measured 5/8", it was likely 3/4" material, which in Plex is not actually 3/4", but a metric measurement of more like 0.708.
What are the tank dims?
Also 5/8" is not a standard thickness for Plexiglas. Is it "G" (with the printed mask) or was there no print on the mask? If it actually measured 5/8", it was likely 3/4" material, which in Plex is not actually 3/4", but a metric measurement of more like 0.708.
I started with a .375 x 48.00" x 96.00" Clear Plexigas Brand Cell Cast Acrylic sheet. It was covered with brown paper. Sorry it was 3/8 not 5/8. The edges were flame polished after routing the edges with about 1/16 of an inch material removed. I also used a polishing wheel on a drill. I made sure the material never got more then warm. The tank is 26x22x20. I think the corners were rounded with a 1/4 inch. I will double check. Here is a shot of top rounding.
I started with a .375 x 48.00" x 96.00" Clear Plexigas Brand Cell Cast Acrylic sheet. It was covered with brown paper. Sorry it was 3/8 not 5/8. The edges were flame polished after routing the edges with about 1/16 of an inch material removed. I also used a polishing wheel on a drill. I made sure the material never got more then warm. The tank is 26x22x20. I think the corners were rounded with a 1/4 inch. I will double check. Here is a shot of top rounding.
Floyd R Turbo
Either busy or sleeping
It's the flame polishing that did it. Nothing you can do about it.
Flame polishing is probably the most stressful thing you can do to acrylic.
Also, 3/8" material for a 20" tall tank is probably OK in an of itself, but then I would think that putting a 1/4" round on it would significantly weaken the material, then flame polishing would stress it more, and then the polishing wheel on the drill would do it even more, so then you're left with an initially nice clean looking corner, but that material has been stressed in multiple ways to a significant extent.
I've seen rimless frag tanks that are only 8" tall made from 3/8" material that were 1/4" rounded that cracked out very easily. Fixed one at MACNA last year actually (it was in my backyard), then saw 2 more at our spring fest. I also see them done that way all the time on eBay...one guy that sells a lot of tanks made this way. It looks nice, but it's a bad idea IMO...
Flame polishing is probably the most stressful thing you can do to acrylic.
Also, 3/8" material for a 20" tall tank is probably OK in an of itself, but then I would think that putting a 1/4" round on it would significantly weaken the material, then flame polishing would stress it more, and then the polishing wheel on the drill would do it even more, so then you're left with an initially nice clean looking corner, but that material has been stressed in multiple ways to a significant extent.
I've seen rimless frag tanks that are only 8" tall made from 3/8" material that were 1/4" rounded that cracked out very easily. Fixed one at MACNA last year actually (it was in my backyard), then saw 2 more at our spring fest. I also see them done that way all the time on eBay...one guy that sells a lot of tanks made this way. It looks nice, but it's a bad idea IMO...
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Bummer... Should I be concerned that the tank will leak from this? The seams are bubble free except for one seam on the top lid. I guess this is how you learn by making mistakes. It's was a great learning experience building my own tank but I'm not sure I would do it again.
Floyd R Turbo
Either busy or sleeping
Probably OK, just doesn't look nice. Seams do look nice otherwise, and if it does start to fail, you will likely see signs of it well ahead of time. James, anything to add?
jagr, check to see if you have a Port Plastics, Laird Plastics, or Sabic Polymershapes nearby. Regal plastic also, or TAP plastics or a few other online places - more expensive, but cut to size. eplastics.com also.
jagr, check to see if you have a Port Plastics, Laird Plastics, or Sabic Polymershapes nearby. Regal plastic also, or TAP plastics or a few other online places - more expensive, but cut to size. eplastics.com also.
crashrat
New member
I would like to do coast to coast overflow on my 60x30x24 and would like it to be external, would this even be possible? The top brace will have virtually no hold on the back, maybe have 3" attach to the top every 18" or so? anyone have coast to coast with their acrylic tank?
Twintank, it's the flame polishing *plus* something else stressed it after the tank was built. Flame polishing itself will not cause crazing, it will just stress it to the point that if something else comes along - bam - you've got crazing. My guess would be one of two things; 1) the tank was made with material that is too thin, bowing badly, and crazing, or 2) and this is the likely scenario; it was cleaned with a solvent based cleaner after being flame polished. Could be Windex or some other alcohol/solvent based cleaner..
Crashrat, what is the tank made from? thickness? C2C overflows are easy to build onto tanks, but easiest/best if built on originally. We build them often, not so bad as the bottom of the overflow will add the lost rigidity as long as you leave the "meat" under any crossbraces..
James
Crashrat, what is the tank made from? thickness? C2C overflows are easy to build onto tanks, but easiest/best if built on originally. We build them often, not so bad as the bottom of the overflow will add the lost rigidity as long as you leave the "meat" under any crossbraces..
James
yes and yes. If paranoid, cut the top big enough to cover the external as well. Just make access holes over that area too
James
code_red63366
New member
Im new here and im not very familiar with arcylic (only what I have read up on in the last 2 weeks on other sites so forgive me here if this question has been asked before as I have tried to read through this post and since there are 116 pages of it and i will need an answer by late morning on wether to buy this used tank or not im gonna ask). Anyway My question is as follows: I am looking at a manufactured used acrylic saltwater tank that is 160 gallons. It has 8 months lefted on the manufacturers warranty and the tank will hold water or so i am told by a local pet shop. The tank is 2 years old and seems to be in pretty decent shape minus a few small swirl scratches and it needing to be cleaned up. Now what bothers me is this,,,,, In the edges where it was welded together I can see some crazing going on. it doesnt follow the entire edge from one end to the other,, just in spots. They guy was asking 500.00 for it but i was easily able to talk him down to 300.00 but after seeing the web crazing at the seams im begining to wonder if I should pass thistamk up or take a chance on it? All of the pieces are made out of 3/4 and the exact dimensions im not sure on but will guess,,,,,maybe 60 or 72 in lenght by 1 1/2 to 2 foot wide buy about 30 inches tall? (im not sure on this). I dont have a whole lot of money to spend on this hobby up front so this will be an off and on project to put together a tank and set up. Maybe it would be just better to save the money for a tank that will hold up with a warranty? That could take me a while to get enough for an acrylic but if this crazing isnt a serious issue and is normal then maybe i can check the tank off my list?If I have lefted anymore needed info or specs out,, do let me know and thanks for any input on this
