DIY- "Pins" method of gluing acrylic.

[melev]

James - Maaan are you far away! I'd have to reallllly want that tank.

Are you aware of any issues with bonding Cell Cast to Extruded? I was thinking that I could buy 1/2 sheet of GP for the front, back and sides, and the bottom and top could be FF. Unless that is a chemical no-no. A full sheet of 3/8" costs me $125.

 

[Acrylics]

Are you aware of any issues with bonding Cell Cast to Extruded? I was thinking that I could buy 1/2 sheet of GP for the front, back and sides, and the bottom and top could be FF. Unless that is a chemical no-no. A full sheet of 3/8" costs me $125.

There are no issues in with regard to this. I've done it many times and works just fine. Not preferrrred - but works
"Chemical no-no"... cute...

James

 

[Zephrant]

Thanks for the info guys- That sounds like a plan Melev- 20" is about my max at 3/8". I'd do a 2.5" frame around it at least, maybe 3". That will help some.

Zeph

 

[melev]

Let me toss this one out there as well. Same concept, just changing (bending?) more rules....

Can I use 3/8" for the walls, and 1/4" for the top and bottom? I only ask because I have excess 1/4" on hand. The bottom will sit on solid wood (or a 1/2" foam pad to avoid stress points), and the top will be mostly cut out (3" lip?!?!!!! I'd much prefer 1.5" max!).

 

[Zephrant]

Melev- I've seen tanks that use a lighter thickness on the bottom (or end panels). Especially the large tanks. It does depend on the depth of the tank, and the span. While the bottom of the tank is fully supported, the sides are not. Picture what happens if you glue only the front to the bottom, then pull outwards on the front. The bottom will flex, until it, or the joint, breaks. That is the same type of forces being applied in the tank, so you don't want to go ultra-thin on the bottom.

For a 30x20x20, I think you might be OK.

Zeph

 

[Acrylics]

Let me toss this one out there as well. Same concept, just changing (bending?) more rules....

Can I use 3/8" for the walls, and 1/4" for the top and bottom? I only ask because I have excess 1/4" on hand. The bottom will sit on solid wood (or a 1/2" foam pad to avoid stress points), and the top will be mostly cut out (3" lip?!?!!!! I'd much prefer 1.5" max!).

Ah, bending the rules again eh?

Question: Are you using one cutout or two?

If just one cutout, you'll want the wider flange (lip). If you can live with two cutouts, use the smaller flange but you get the centerbrace.
Perhaps a happy medium, one cutout but use a 2" flange with a larger radius on the cutouts - say a 2" or so. This will help distribute stress over a larger area than the 1/4" radius that a standard 1/2" flush cutter leaves.
I would worry about using 1/4" FF for the top though, extruded material is more sensitive to stress and heat and the heat from reef lighting *may* cause issue depending on how much heat the top actually receives. The again I may be worrying too much...been known to happen.

James

 

[tricky]

I am building a sump for my new 175 Oceanic Bowfront. It is a new stand design that gives me room for a large sump/refugium down below. It is trapezoid in shape to maximize the area. I am building it with the largest dimensions that I can and still removable from the front. I is around 60 gal, measures 43 1/2" length, one end is 15 1/2", the other 22" and 18" tall. I am using 3/8 plexiglas G.

I am about ready to start gluing, and found this great thread, thanks guys! The first joint will be attaching the back (cut to fit inside the ends) to the bottom. The second glue operation will be two joints, one to the bottom and one to the back after it has set. It looks like the pin spacing method will work as described in this thread for the bottom joint, but how about the joint up the back? The shim method won't work here, and it does not have the weight of acrylic for clamping pressure. Would you recommend using bar clamps?

Also, any thoughts on the design? I have not finalized how much space will be dedicated to sump and how much is refugium, but I will likely end up with internal dividers that would add bracing. Do you think it might be necessary to add an inside lip at the top for bracing?

:thumbsup:
Thanks,
Rick

 

[melev]

You can still use the pin method for the "up the sides" sections. You just can't put a pin near the bottom joint, but about 8 to 10 inches up from the joint you can start using pins.

I add a solid piece to the top, routing out the hole if it is needed. The best way for me to decide is once the unit is built with the internal baffles, has been allowed to cure for 24 hours, I fill it up with water and inspect it closely for swelling. If the unit gives too much, I add the top piece. Usually, in cases where the vertical height is pretty tall (20" or more), I add it.

 

[Acrylics]

It is trapezoid in shape to maximize the area. I am building it with the largest dimensions that I can and still removable from the front. I is around 60 gal, measures 43 1/2" length, one end is 15 1/2", the other 22" and 18" tall. I am using 3/8 plexiglas G.

Tough sump to make for many, the trapezoidal shape requires machining and gluing angles which can get difficult

The first joint will be attaching the back (cut to fit inside the ends) to the bottom.

It is recommended to glue the bottom on last, you can control flatness and warpage easier this way, but...

The second glue operation will be two joints, one to the bottom and one to the back after it has set. It looks like the pin spacing method will work as described in this thread for the bottom joint, but how about the joint up the back?

Maybe change the order in which you are gluing so that you are always gluing on a horizontal plane. Perhaps glue the ends to the back then flip the whole thing over onto the bottom?

The shim method won't work here, and it does not have the weight of acrylic for clamping pressure. Would you recommend using bar clamps?

Bar clamps have a tendency to squeeze out any solvent, leaving a "dry" joint. I use them often for gluing heavy gauge but would not at all recommend them for thin stuff

Also, any thoughts on the design?

If you can post a drawing of what you've got/want, I'm sure if we all put our heads together...

I have not finalized how much space will be dedicated to sump and how much is refugium, but I will likely end up with internal dividers that would add bracing. Do you think it might be necessary to add an inside lip at the top for bracing?

Depends on design, to tell the truth

HTH,
James

 

[tricky]

Thanks for the comments, it's helping a bunch. I can seen how attaching the bottom last would have been better. I thought there would be more matching problems attaching the bottom to four separate pieces, but that has not been problem at all Everything is real square. A bigger problem is trying to glue a vertical joint.
The problem I am having with the vertical joint is the gap is not very controllable. The gap is too wide, the solvent flows down the joint and I couldn't get the gap to fill. I started at the top, the solvent just ran down the gap and started filling near the bottom. Without a clamp or the pressure of the plexi, there is not enough pressure to close the joint far enough. I did manage to get a nice, just had a few bubbles, but it was getting scary for a little bit. :eek1: BTW, the framing squares is a GREAT trick, it really keeps everything square and solid. I managed to use one square with a pile of lead scuba weights piled on it with wooden wedge to put some pressure from the outside in, it worked well.

The trapezoid shape has not been a problem so far. The angle cuts are only 9 degrees from square. I use a 10" 60 tooth carbide tip blade on the table saw, then dress it down with a flat mill bastard (file). It took quite a few hours for the hand dressing, but it all came out really nice.
I am ready to glue the front in place. It sits on top of the bottom piece and overlaps the two end pieces. I am considering joining it to the bottom with the pin method first, then letting it dry. Then turn it on the front to one end, dry again and the other end. Would this give the best joint? I am concerned that the glue will wick up the vertical joints when I try to stop in the corners.

Sorry for open ended question about sump design, I was actually concerned about the thickness for the size of the sump right now. Thanks, melev- I will see what it looks like on the leak test. Went I get the box built, I will post a layout for some ideas.

Thanks
Rick

 

[melev]

One day I'm going to have to try attaching the bottom last. Like you, Rick, I figured it would be difficult to get a flat surface bond with it being added last. I always attach my walls to the base, one by one.

You mentioned vertical gluing... can't be done. It must be horizontal for gluing, unless I misunderstood your post.

 

[tricky]

Melev, you are giving me confidence. Guess I did the impossible!!:wildone: Seriously, it can't be done well is what we'll agree on. I close the gap, got it to fill rather well, but isnt a piece of art. It looks like it will be strong enough, but just to make sure I am going to run a bead of weldon 16 on the inside. So what I hear you saying is I should be able to glue the bottom, let it dry, turn it to do one end, then the other?

Rick

 

[melev]

Melev, you are giving me confidence. Guess I did the impossible!!:wildone: Seriously, it can't be done well is what we'll agree on. I close the gap, got it to fill rather well, but isnt a piece of art. It looks like it will be strong enough, but just to make sure I am going to run a bead of weldon 16 on the inside. So what I hear you saying is I should be able to glue the bottom, let it dry, turn it to do one end, then the other?

Rick

Acrylics or Zephrant will probably chime in as well, but if your gap is really problematic, you can put a small piece of acrylic over the spot, and weld that in to act as a patch/bandaid.

Using #16 is pretty messy and hard to control, until I went to a hobby shop and bought a pack of 5 long tips. They didn't fit of course, but I cut the end so it would spread just wide enough to be forced onto the tube of #16. It allows me to just apply where I need it, in lesser amounts.

And yes, glue your horizontal seam, allow it to dry, turn the entire project until your next seam to be glued is horizontal, and continue until all seams are done.

 

[tricky]

Thanks, Marc. It worked like a champ. The bottom seam is done, and it didn't wick up the sides very much at all. If I look real close, I might find 1 or 2 bubbles in the entire 4' seam. It'll be a piece of cake to do the sides now.

My weldon came in a can, I will probably need some kind of syrenge to apply it, I probably have something around that will work.

Rick

 

[melev]

#16 came in a can? I always get it in a tube, like airplane modellers glue.

 

[tricky]

Yep. My local supplier has it in the tubes or the 1 pint can for about $7.

 

[skripo]

I have been trying to make an that is less sealable than 2 mated flat surfaces. How do you recommend I do this in 1/4 acrylic and what tooks do I need.

Thanks

 

[melev]

I have been trying to make an that is less sealable than 2 mated flat surfaces. How do you recommend I do this in 1/4 acrylic and what tooks do I need.

Thanks

Can you retype that sentence? It seems to be missing some words, or I'm too tired to understand.

If you'll go to the beginning of this thread it explains how to bond acrylic nicely.

 

[skripo]

I must have been dreaming, here it goes again:

I have been trying to make an O-Ring but the seal always comes out worse than 2 flat surfaces with an O-ring between. How do you recommend I do this in 1/4 acrylic and what tools do I need.

I am also looking to make the seal flangeless, just a quarter turn should unlock it. Any ideas?

Thanks

 

[melev]

Zephrant, I'm reviving this thread because my seams are still a tad messy. I'm getting good bubble free seams for the most part, but too much product oozes out.

I'm currently using twist ties that come with trashbags or sandwich baggies. What size wire would be ideal, and would it be something I can find at Home Depot perhaps? Or Fry's Electronics?