Acrylic fabrication questions? I can help!

[Italian Stallion]

i am having trouble using my router table because it is 2 small and i cant get any feather board on it

any suggestions on how the get a straight cut




also how hard is it to run acrylic throught a planning jointer? do youy have to use featherboard or anything to keep it stable or does regular hand preassure work ok

[Flavorflave]

Acrylics, I found this in a thread from july last year. you made specific comments about the cell cast acrylic that is sold by Laird Plastics below. Bottom line, do you think that this acrylic is worth using and do you think that 1/2 inch or .47 inch thickness is enough for a 84x30x24 tank?
Lastly, what is a fair price for a tank like this made right?


Plesiglas GM is pretty good material, the rest of it is incorrect. Plex GM is made in Mexico so not exactly domestic (it's nickname is "MexPlex", and is made in a horizontal waterbath cell while Polycast is made in a vertical cell - does this stuff matter? not really but does show your instincts correct Unless he simply referring to "cell cast".
It's slightly cheaper than Polycast and not *quite* as good IMO but still good material. TruVu uses Plexiglas quite a bit for their tank as do many mfrs so is very suitable for aquaria.
The reasons I don't use it much, in case you're wondering, are four-fold, but none of them major.
A) does not come with the overage that Polycast does. A 4 x 8 of 1/2" Polycast measures 51 x 100, MexPlex is usually 49 x 97. The extra coupla inches makes yields come out better for me.
B) Generally, only comes in a handfull of colors, clear, black, white, bronze, and that's basically it. There are other but large minimums must usually be met.
C) For the most part, distributors only stock 4 x 8 sheets, while 5 x 8' and 6 x 8' sheets of Polycast are not at all uncommon.
D) MexPlex thickness is metric so 1/2" is actually 12mm (.472") while Polycast is imperial thickness so 1/2" actually measures .500".

Thanks for all the help.

[Acrylics]

Originally posted by juststartingout
Make a long story short, they were out of Acrylite GP, so I bought Plexiglas G. I read that Plexiglas G is made in Mexico and it is actually .472, instead of .500. Will this be alright to use? I thought in an earlier post that someone said to stay away from import materials. Thanks for your time!

As M23 points out, it's fine material. Polycast is about the only readily available material that actually specs out at .500 for 1/2". Virtually every other mfr has gone metric including Cyro (mfrs of Acrylite). They did this about 15yrs ago and said it was to get in line with the rest of the world but IMO it was a price increase without actually calling it a price increase
Generally speaking though, Plex G will yield thicker material than Acrylic GP in 1/2" as *in general* Plex G will actually measure between .450 - .500 while Acrylite GP will usually measure out at .440 or so. The Mexican made material is usually pretty good stuff as both of the big plants in Mexico (Atohaas & Plastiglas de Mexico - AKA Chemcast) are both German engineered facilities, in fact by the same folks.

Originally posted by Flavorflave
Bottom line, do you think that this acrylic is worth using and do you think that 1/2 inch or .47 inch thickness is enough for a 84x30x24 tank?
Lastly, what is a fair price for a tank like this made right?

Most mfrs would use 1/2" (or 12mm) for this size tank so yes - it is the standard thickness. And the material itself is good material. You should expect 1/8" - 3/16" of deflection at 12 weeks which isn't terribly bad. As far as pricing for this size tank, it's an odd deal really as the 84" length is a bad yield because many times you have to eat the drop off - remember sheets are usually 96+" so many mfrs will price it as the 300gal (96 x 30 x 24"). Generally speaking though, $1300-1600 is probably the range you are looking at to get it made. Check around with Tenecor and some of the other mfrs to see what you can get.

HTH
James

[Flavorflave]

Thanks James!

[mnreefgeek]

James - Greg/ ReefMania, our local expert is in hiding (I think) so I figured that I would throw this your way.

I have an MR3 that is leaking where the PVC leaves the acrylic body. What do you think is the best fix to cure this leak so I can run the skimmer externally? Someone in a seperate thread said to use Weld On 16, what do you think?

Thanks,
Chad
mnreefgeek

[Vincerama2]

If all else fails, you can glob on "Plumber's Goop" which works pretty good. I have a crappily made kalkwasser reactor where some joint was leaky. I slapped a few layers of plumber's goop on it and it has not leaked since (in 2 years or so).

V

[Scottm]

You could try 16 on that leak but it dries will a lot of air pockets if you put it on very thick. Might take a couple thin applications but should eventually seal it up. Not much pressure in the skimmer box. Probably the best way to seal it the first time is with #40.

[juststartingout]

Thanks for the feedback. Now as soon as I get some spare time I will build it (the sump.

[adrinal]

I am looking for links / tips on best practices/methods for mixing and applying weldon 40

[indguy]

Acrylics, First off thanks for all the info, it is much appriciated!
Using ACRYLITE GP what would be the minimum (no bowing) thickness for a 120 Gal. tank 48"LX24"Wx24"Tall?
Thanks in advance for your insight.

[indguy]

Acrylics, First off thanks for all the info, it is much appriciated!
Using ACRYLITE GP what would be the minimum (no bowing) thickness for a 120 Gal. tank 48"LX24"Wx24"Tall?
Thanks in advance for your insight.

[m23]

I know this is acrylics thread but I thought I would share my knowledge with you indguy. Belive it or not Sea Clear used to build a 120 out of 1/4" and yes it bowed like no other. You could use 3/8", I would use 1/2" if the small price diff. didn't matter. All acrylic will bow to some degree.

[masterswimmer]

I wouldn't use anything less than 1/2" indguy. Personally, I like to overbuild and I'd even consider 5/8". But like m23 said, it will all bow to some extent.

Russ

[Acrylics]

Indguy,

Ditto the two previous answers. 1/2" would be the minimum but it would bow roughly 1/8", if you can live with that - you're golden . IMHO you have to set tolerances rather than saying "no bowing" - hope you know what I mean.

1/4" *may* hold water depending on the top and how it is braced
3/8" holds water but will bow ~1/4"
1/2" holds water well, bow's 1/8" or so, needs crossbrace
3/4" will bow 1/16" or so if yu use a crossbrace, can be eurobraced with wide flange
1" will bow <1/16", a touch more if eurobraced

I think most fabricators would use 3/8", your better ones will use 1/2". Above that, you have to figure there's not much reason unless you want eurobracing as you're spending a bunch more money for little difference.

HTH,

James

[avgjoe]

I was planning a large in wall tank and was curious. Is it feasible to build a tank with 4 sides acrylic and 1 side glass? Or would the difference in thermal expansion of glass and acrylic cause the tank to eventually fail?

[moflow]

The real problem is bonding the acrylic to the glass. Acrylic solvents won't work on the glass and silicone won't bond well to acrylic.

Originally posted by avgjoe
I was planning a large in wall tank and was curious. Is it feasible to build a tank with 4 sides acrylic and 1 side glass? Or would the difference in thermal expansion of glass and acrylic cause the tank to eventually fail?

[avgjoe]

I agree, I don’t think anything bonds with glass. But isn’t it the molding around the top and bottom, that hold a glass tank together? The silicone only acts as a sealant between the joints.

[adrinal]

I think the molding is mostly for looks, and to ease a little stress, not for water tightness.

[Acrylics]

IMO the best way to do it would be to make the acrylic tank with a 3" or so flange on the front with the glass on the inside. Using a liberal amount of silicone (DC 795) to act as a gasket between. The force of the water would be pushing the glass into the silicone gasket, thus strengthening the sealing effect. This is exactly the way large fiberglass tanks are made but usually with acrylic windows, I believe plywood tanks are also made in the same manner. It may be necessary to actually place the glass prior to gluing the last side on the tank but is certainly possible. If you're gonnay try it, I'd definetely recommend way overbuilding it though

HTH,
James

[avgjoe]

Thanks Acrylics. I learned alot in that post. Didn't even know fiberglass was an option. Did a google search and found exactly what I had in mind.
http://www.fiberglasscreations.com/images/aq2.jpg
http://www.aquaticeco.com/index.cfm/.../4165/cid/1171

[indguy]

Thanks everyone for the help. I think I will go with the 1/2" with a cross brace. 1/8" deflection is not a problem.

[Italian Stallion]

am having trouble using my router table because it is 2 small and i cant get any feather board on it

any suggestions on how the get a straight cut




also how hard is it to run acrylic throught a planning jointer? do youy have to use featherboard or anything to keep it stable or does regular hand preassure work ok

[Ehydo]

use a rip guide on the opposite side

[Italian Stallion]

where can i get a rip guide (website linck) and what is a rip guide

[Ehydo]

Originally posted by Italian Stallion
where can i get a rip guide (website linck) and what is a rip guide

AKA Rip Fence.

Just clamp down a piece of wood.


http://benchnotes.com/Fence/fence.html