Acrylic fabrication questions? I can help!

[ReefEnabler]

I had success at the medical supply store near the local hospital. They had 30 and 60cc syringes so I got half a dozen of each

going to try out my WO40 skills on my 1st ever 6"x6"x6" test tank to make sure it goes smoothly.

 

[fishboyy]

hey guys i posted a thread and it was suggested i post it here in this thread to get good answers from knolegable people


ok so im setting up an 8 X 3 X 10in frag tank one of the acrylic seams is "busted open",
i was told to fix the seam with weldon 4 and put a scrap piece of acrylic on the out side of the seam just for "good measure", then it was suggested i use weldon 16( really thick) and use it like a caulk on all the seams to re inforce them.

So i went to the acrylic store and the guy there told me use the 4 and piece of scrap but don't use the 16 becouse it wont do anything to hold water out, he said i should use silicon like a caulk only if i wanted, this confused me becouse i thought silicon didnt make a water tight seal on acrylic,

PLEASE help any suggestions would be GREAT thanks

 

[Acrylics]

Don't bother with the silicone. For the most part - silicones won't work for anything structural when it comes to acrylic. Get yourself a piece of 1/2" square bar and glue it into the corner as a gusset after you glue the seam back together. Most larger acrylic shops sell 6' long pieces of exruded square bar, cut that down to your 10" and glue that into the corner.

Do not use 16 as a caulk, people that do this are fooling themselves into thinking it's going to help in a structural way but it won't, at least not in a significant way. It kinda acts as a seal but not a very good one IMO. My feeling is who cares about a seal if the joint is going to bust open and if the joint is strong enough - no need for any other kind of sealant. Make the joint itself strong and that's going to provide the seal.

HTH,
James

 

[fivesmallworlds]

I plan on making a sump from acrylic 40Lx16Wx16H. What thickness of acrylic should I be using? Is Plexi from my Local Hardware Store going to be ok, or is there another brand that I should be looking for.

TIA

 

[Acrylics]

Hardware store will most likely only carry up to 1/4" and most likely extruded material. 1/4" extruded will be "okay" if braced properly but would recommend a thicker cell cast acrylic such as Polycast, Cyro Acrylite GP, or Plexiglas G/GM. Check your yellow pages under plastics distributors if you decide to go with these.

HTH,
James

 

[fivesmallworlds]

Great, thanks so it sounds like using 1/4" will be ok, but cell cast would be a better choice than the extruded kinds at the LHWS. I know I have a local acrylics shop that I can call. Thanks again.

 

[fishboyy]

ok yes thats helped alot thanks!! would it help to silicon the other already done seams in case of a leak?

 

[Acrylics]

<a href=showthread.php?s=&postid=12499044#post12499044 target=_blank>Originally posted</a> by fishboyy
ok yes thats helped alot thanks!! would it help to silicon the other already done seams in case of a leak?

It won't hurt but very doubtful it would help any either. The big downside is that if you ever have to repair that seam, the silicone there will be a hindrance to do so; even if you removed as much as possible, the residue may cause problems.
If you have a leak, fix it, trying to "seal" it with silicone will only delay the inevitable. Best to fix it right

HTH,
James

 

[madmike]

James I have a quick question about how you use weldon 16. Everytime I place a bead in a seam, I tend to get massive air pockets that get trapped in the bead that seem to form from within. Any hints on how to avoid this?
Thanks

 

[Acrylics]

MadMike,

Wish I could help with that but 16 is something I avoid like the plague. I've used it *once* in 20 or so yrs doing these things and didn't like it at all so something I leave alone.
I do know that it has alot of air in the mixture to start with so that may be some of it.
Hopefully somebody who is proficient with it will chime in.

James

 

[madmike]

what do you use around the edges of your overflows? Both tanks I have are built by you and I see they have a bead of something around the external overflows.
Thanks
Mike

 

[Acrylics]

Weld-on 42
Similar to 40 but used with an applicator gun and static mixing tips, same as many 2-part epoxy guns.

Only reason I do that is that I can't see the joints in black or blue so it's just an "insurance policy" of sorts.

HTH,
James

 

[fishboyy]

ok great thanks soo much!!!

 

[madmike]

ok thanks!

 

[RokleM]

I've used Weld-on 16 to run a bead in a couple cheap sumps/refuges. It goes down just like 40, but very quickly either sucks in air or evaporates. 40 is a much better solution, and I won't bother wasting time even trying 16 in the future.

 

[BeanAnimal]

I have never had good luck with 16. It goes on VERY thick but evaporates to a very THIN profile. The stuff skins over very quickly then evaporates from the inside, leaving air pockets.

 

[chriscobb]

Anyone know where to purchase Weld-on 42?

 

[kgross]

Most plastics distributors in your area will have weldon 42. Check your yellow pages for plastics rod and sheet and give them a call.

Kim

 

[chriscobb]

Yeah local plastics dealer doesn't carry it.....I've been there, and quite frequently there.......

 

[Acrylics]

Any IPS distributor can bring it in but they have buy a case (12 cartridges), you can call IPS and ask who has any in your area. www.ipscorp.com
If you still can't find any, lemme know. Remember though, you'll need the gun and static mixing tips

HTH,
James