HOW DO YOU CEMENT REALLY THICK ACRYLIC?

[Trixter]

Im new here but am working up to a larger project. I read the other posts but still am confused about how to cement really thick acrylic panels 10FT long and 1.25" thick. Tired of hearing, it cant be done. What method is best to ensure solvent penetration on a project like this?

2 part polymerizing adhesive, i.e Weld On #40/42 or single part solvent.

OR

Solvent cement using the capillary method (dont think this method would penetrate 1.25" thickness well enough though)

OR

3. Build dam from tape, install pins, pour cement inside dam, remove pins from center going outward? Jig brace panel in 90 degree position?

What type of cement though 2 part adhesive or thick 1 part solvent type i.e Weld On 16.

Any information you guys could provide would be greatly appreciated.
Thanks again

 

[Anonymous]

Well, it can be done, but, my experience is limitted to 3/4" and under.

I watched a guy start to build a 10' tank using 1.25" though. He had to use a motor pully (small crane ) to lower the panel into place. I wasn't there for the gluing though, sorry.

 

[Anonymous]

I don't see why the wire/pin method won't work, but I never deal with such thickness. I will wait for James to chime in and see if he will give you some trade secret....

 

[FragMaster]

With that size I would dip it. ( literally dipping the edge in the cement until it softens.)
But I dont see why the pin method wouldnt work either. Its basicly the same as the dip method.

 

[Acrylics]

You can use either 40/42 or solvent, some of this will depend on how precise you can machine your pieces. If you are able to machine your pieces +/- .005" or so - you can use wires/pins. We use the exact same process for solvent gluing this thickness as 1/2" so that part doesn't change - just the weight and manageability of the pieces.

If you cannot get the pieces machined that closely, then 40/42 is the best method.

If machining is good then between the two above processes, use the one you are most comfortable with. Both will work just fine.

I would *not* use #16 for such a tank at all.

BTW the "pins" method *is* the capillary method - just using surface tension to wick the solvent along, the wires or pins just make for a larger gap.

Out of curiosity, what are the fill dimensions of the tank and what size are the flanges / crossbraces.

HTH?
James

 

[Anonymous]

Hey James!!!!

 

[Trixter]

Thanks all of you for your input, please keep the ideas coming.
Sorry forgot to mention the dimentions, they are 120 X 24 X 36 1.25" Polycast GP.

Fragmaster

I thought about dipping it but wasnt sure about how to make a 10FT long shallow trough with a completely flat bottom so that the solvent would just barely wet the edge. I mean at that length it could be difficult to make a trough that is completely flat on the bottom so that the depth of the solvent bath would be uniform throught the trough to keep the solvent from coating the sides and weakening them.

James(Acrylics)

Roger, no #16. All sides including the top and bottom are 1.25" thick. I have some ideas for the top cutouts but nothing firm yet, really need to hear from a pro such as yourself. Im going to take the acrylic to a Fabrication shop to do the edge machining (Any recommendations for a good shop in Colorado)? and do the assembly work myself. Mainly because the tank wont fit down the staircase assembled so I have to assemble it on site. Im hoping that the Fab shop can get the edges this smooth and flat and I can use solvent cement instead. Due to the size and thickness of the panels Im thinking they will probably use a 3HP router to plane the edges. I will take your advice, I was leaning towards the wire/pins method also. Regarding the dam part, am I right by building a dam of tape around the joint to be cemented?
Do you think I should use a thicker 1 part cement to manage the flow better or the watery stuff with a needle applicator?
I noticed in other posts you dont recommend wire over .015 so I'll use the bread tie wire as suggested, have even heard of using fishing line?
Oh...should the edges be beveled at all?
James your an awsome resource.

Sorry for the long reply, would like to hear any ideas you all have

 

[Acrylics]

Roger, no #16. All sides including the top and bottom are 1.25" thick. I have some ideas for the top cutouts but nothing firm yet, really need to hear from a pro such as yourself. Im going to take the acrylic to a Fabrication shop to do the edge machining (Any recommendations for a good shop in Colorado)? and do the assembly work myself.
Sorry, no shops that I know of other than Reynolds in Grand Junction and I sincerely doubt they want to do this. They do *mega large* tanks for public aquariums and only want to look at 6-digit jobs.

Mainly because the tank wont fit down the staircase assembled so I have to assemble it on site. Im hoping that the Fab shop can get the edges this smooth and flat and I can use solvent cement instead. Due to the size and thickness of the panels Im thinking they will probably use a 3HP router to plane the edges.
That's what I'd use as well so you're on the right track

I will take your advice, I was leaning towards the wire/pins method also. Regarding the dam part, am I right by building a dam of tape around the joint to be cemented?
This shouldn't be neceesary at all, surface tension itself keeps the solvent at the seams

Do you think I should use a thicker 1 part cement to manage the flow better or the watery stuff with a needle applicator?
With practice, you will easily be able to control the flow of the water thin solvent and thickened solvent gets too sloppy, esp on something this size.

I noticed in other posts you dont recommend wire over .015 so I'll use the bread tie wire as suggested, have even heard of using fishing line?
Yep, done that as well problem is the the properly machined edges are very sharp and will cut the nylon fishing line due to the weight. Twist ties are use simply because they have all the attributes that I want in a wire. I personally don't like pins as they are too thick and the gap is too large for the solvent to wick properly causing the solvent to run all over the place.

Oh...should the edges be beveled at all?
nope, 90deg will be just fine

James your an awsome resource.
Too kind <blush>

I'll see what I have in my pic library of 1.25" tanks, I know there are a few but finding some that will show the methods will be another story.

HTH,
James

BTW, Hi Matt

 

[Trixter]

Cool thanks.

 

[Anonymous]

Yeah, Reynolds in GJ is great. They help a project with a large spherical acrylic container for underground neutrino detection or some sub-atomic physics. I think that was a multi-millions job.

 

[Trixter]

bump

 

[Trixter]

Was going to mix some Weld on #5 with #4 to slow down the cure time allowing me to complete long panels and remove the wire before it sets. Ready to practice now with smaller peices but cant find the #5 anywhere so I read a few older posts that glacial acetic acid could be mixed in low quantities with #4 to slow the cure time down producing a stronger bond? Anyone know where I could find either one of these, #5 or glacial acetic acid. Thanks for your input.
/R
Sean

 

[Acrylics]

Sean,
Adding acetic acid doesn't *necessarily* make for a stronger bond but will act as a buffer to slow down the reation and help the solvent flow better. Find it at local laboratory supply house. Don't use more than 8-10% though or the joint can get a grainy look to it.
AFAIK, #5 has been discontinued but not certin of this. FWIW, #5 was methylene chloride, acetic acid, and acrylic monomer. The only difference between #3 & #4 is the ratio of methylene chloride (MC) & thrichloroethylene (TCE), So you can add acid to either one. Or buy lab grade MC at the same lab supply house.
For gluing the tops & bottoms of long tanks of thick material, start at a corner and do one panel, go around to other side and do the opposite panel while a helper is pulling wires on the first side, it gets intuitive once this gets done

HTH,
James

 

[Trixter]

Thanks James
Im going to see if I cant find some of the glacial acetic acid around here. Im hoping that it will slow the cure time down enough to allow me to complete the seams properly. After everything has dried, would it be wise to go over the inside seams with a bead of #16 to be safe? I know you said not to use it for initial bonding though. Thanks for the help.
/R
Sean

 

[Acrylics]

While #16 can work for smaller sumps, reactors, & that sorta thing - it will do little if anything on a large display tank as the pressures are too great. If you were to do *anything* like this, I'd recommend Weld-on 40 though if the joints are good - will not be necessary by any means.
Don't worry, we'll get ya thorugh this

HTH,
James

 

[Trixter]

Thanks James, I read that from an old Acrylicman post years ago. One of the Chemistry guys around here said its similar to the acid found in vinegar. Even heard someone say to add a very small amount of #16 to #4 to slow #4 down. Im staying away from #16 for this job. Its hard to believe nobody has published a step by step DIY book about this yet.

Sean

 

[Anonymous]

Some of the hardcore DIYer has a copy of The Acrylic Handbook, which is about $200. It is a good reference for anyone who is serious about working with acrylic.

 

[Acrylics]

Hi Sean,

Your chem guy is correct, vinegar is 4-5% acetic acid. The idea of adding #16 to #4 to slow it down doesn't work any better than simply adding acrylic shavings to #4. It doesn't actually slow the reaction down at all (chemically), just adds a filler - similar to using PVC pipe cement instead of straight THF. Plus, clogged needles just suck

As far as a step by step book, I have been working on it for a coupla years now but extra time is hard to find. Maybe when I retire Anyone who does this for a living is generally not going to give away many "trade secrets" out of fear of slitting their own throats - fairly certain you know where I'm coming from on this. I have a different take on this but that's another story...

Hope all is well,

James

 

[Anonymous]

Sorry, it is Handbook of Acrylics for Submersibles, Hyperbaric Chambers, and Aquaria by Jerry Stachiw

With more than 1000 pages, it is not a handbook per se.

 

[Trixter]

Know what you mean James. Im going to practice mixing a little glacial acetic acid (if I can get it) outside this weekend and cement a couple of scrap peices together to see how it turns out. This is interesting stuff. I wonder if the Scripps institute would be worth checking out down here. I mean they mess around with submersibles Im thinking. James have you ever read this book?

Seven, I requested that book through the local library here. The University of San Diego has a copy Im requesting to borrow through a local branch of the library, cost me 2 bucks just to request it. Your right that is one high dollar book. Have had my eye on it for awhile. Have you ever read it, I wonder if it contains any useful info?

Sean