DIY- "Pins" method of gluing acrylic.

[Zephrant]

There are many ways to glue acrylic. This is the method I use when I want strong, clear seams.

Required: Weldon #4 or McBond acrylic solvent, and sewing pins.

The acrylic solvent creates the joint by dissolving a little bit of each piece, then evaporating out and letting the two pieces co-mingle, creating a strong bond. Contrary to popular belief, the joints are not stronger than the sheet. See Here:
Weldon #4 is fine for small tanks and sumps, as well as skimmers and similar. If you are building a large tank, I would consider Weldon #40 though, it is 3.5 times stronger.

This method only works with the water thin solvents, like Weldon #4 or McBond.

The key to good clean joints, is a good edge. This can be made with a jointer, or with a router in a router table. If you cant beg/borrow these tools, you may want to consider using the gap filling Weldon #16 instead (Weaker joints than #4).

The following is the best method that I have determined- Modify as needed to fit the tools you have on hand.

Start by rough cutting the material on a table saw to 1/4" larger than needed. Make another pass though the table saw, taking off a little less than 1/8" on each side. This should leave nice edges on the piece, but it will be about 1/16 oversize.

Left side- Saw cut, right side- Jointed.

Using a jointer, or router and a fence, take off 1/32 on each side leaving a clean, smooth edge.

Lay out the bottom sheet, and brace the vertical sheet above it. Slide in a pin on each end of the sheet, and about every 6" in between. Most pins will be too tight/too loose at this point. Don't worry yet, just get them in place.

For each pin, slide in a wedge of wood under the bottom sheet, to lift it up until the pin is snug. Repeat for all the pins. Check them all again, pushing in each wedge a little until every pin feels the same, neither loose or pinched. Check one more time because if you missed one, that is where the bad joint will appear.

It should look like this:

(cont)

 

[Zephrant]

Now comes the fun part. Put the glue in a squeeze bottle, or a glass syringe available from the plastic shop, or your local addict. (Drug addict, not reef addict. )

Note: I could not get pictures on the above tank without risking a bad joint, so here is a couple of pieces of scrap being glued. Imagine it is a bigger piece, with shims under each pin as above.

The water-thin solvent is placed next to the joint, and it will wick in to the joint filling it completely. With a little practice, you can wick it in without getting any air in with it. If you get a bubble or two, don't worry. Trying to get it out will make it worse. When you get to the next step, most bubbles will squirt out of the joint.

Last step: Let the solvent sit for 30-90 seconds, depending on the temperature. Start pulling the pins out at one end, while bracing the piece with your other hand. Quickly get them all out, and realign the piece as it will shift some when you are yanking the pins. Use a pair of needle-nose pliers if needed, they can get glued down pretty well.

With ALL the pins pulled, realign the sheet in to location and hold it for a minute. If you miss a pin, it will bugger up the joint. After the piece is not going to float away by itself, go around to each wedge and snug it in a touch. If it is not tight, the joint will separate and make bubbles.

Hot tip: Don't over snug the wedges. If you start at one end of a tank and go around snugging up every wedge, you can end up at the start again which has become loose because you lifted the entire tank 1/8" as you went around. Again, practice is key.

Bracing a sump end: Note the corner has been knocked off of these cheap plastic framing squares. I use double-sided masking tape to hold them down.

Don't touch it for 4 hours. Let it dry for 24 hours at room temp. before routing it. In 4 hours, you can flip it over and do the other side though, then let it sit overnight to cure.

Read the IPS web page for your glue. It has good tips (link above) as well as serious health warnings. I always use a respirator, as well as cross ventilation to the outside.

With practice, you get perfect, clear joints.

If you do get a joint with some bubbles in it, install a triangular wedge of acrylic in the joint corner to seal/strengthen it.

HTH-

Zeph

 

[dattack]

Thanks for the info!

So when you glue a side to the bottom piece of acrylic, is the pressure from the weight of the acrylic good enough? Or do you have to weigh it down ?

 

[Cheapreef]

Yeah thanks for this one too. Do you find the weldon 4 to be that much slower or easier to work with than #3. Just asking cause i've only ever used #3 and #16.

Clinton

 

[wanareef]

dattack- no, the use of weights or clamps in not necessary or desired- just the weight of the piece is enough

cheapreef- #4 is suppose to be slower that #3 but I have not used #3

hth

 

[Cheapreef]

Thanks, already read that on the manufactures web page, just wanted to know form first hand experience.

Clinton

 

[JDM130]

Zeph,
Great reading and pics! Thanks for taking the time to show us all this very informative thread. I'm sure that many DIY'ers will get a lot of use from your generous input.
Thanks!
Jeff

 

[Zephrant]

Dattack- I don't normally weight down the end pieces, but when I put a bottom piece on, I place a bucket or two full of sand across the frame to help drive it deeper in to the base piece. Not sure if it makes much of a difference, but that is definitely the joint to make the strongest.

I have not used #3, I find that #4 is plenty fast for me. Putting the bottom on a 8' tank is a 100 yard sprint already, I'm not sure it could be done well with #3.

Your welcome all.

Zeph

 

[H20ENG]

Great job, Zeph!
I've been putting together a similar thread, but now I dont have to finish it!
A picture here is truly worth a thousand words. We've been trying to explain all this for months, and there you see it.
Did you have fun trying to click the pics and run the glue at the same time? That was tough for me!
Chris

 

[Zephrant]

Hey Chris- Yep, I only got one shot and the joint was filled. Please throw up your pictures too- More pictures would be great!

Zeph

 

[fixmgood]

Zeph,
It is through people like you, who are willing to share great ideas and know how that makes reading this board so worth while.The obsession has me in its grip.Can't wait to try it out:bum:

 

[aajenki]

Zeph,

Do you use the same method for gluing smaller jobs such as a Beckett skimmer box, 6" riser tube to the top of box or flanges to tube?

Aaron.

 

[Zephrant]

Fixm- Thanks- It is comments like that, that make it worth my time.

Aajenki- Not usually. Using the pins method on tiny pieces that are not under much stress is a lot of trouble. For the boxes, I often just use Weldon #16 on one piece, then mate them together and put a weight on it. I make sure that the #16 oozes out both sides of the seam, and dries with a full fillet on both sides. Then I flush trim the outside away.

For the tube to box and tube to flange joints, I cut a 1/8" groove in the sheet material that is a snug fit to the tube. I fill it 1/2 full of Weldon #4, and wait about 1 minute. Then I drop the tube in to place, into the softened groove and put a weight on the top of the tube. This makes a very strong joint, that does not ooze out extra so it looks very clean.

Cutting the groove is a pain. I use a fly cutter in the drill press that has been carefully ground to the right size. I also use a vacuum clamp fixture to hold the flanges to the table of the drill press (actually a mill, but it acts like a drill in this case). Without a vacuum pump, you can use any kind of clamps that will work. I have even temporarily put wood screws though the "thumb-screw" holes to hold the flange in place while I cut the grooves (O-ring on one side, and Tube on the other). I cut out the middle of them last, as I need the 1/4" pilot hole in the middle for the fly cutters.

Sound clear?


Zeph

 

[melev]

Excellent information Zephrant. Thanks!

 

[aajenki]

Zeph, that's great. Thanks mate.

I have tried Weldon 16 a few times but it has not formed a nice fillet either side of the joint. Instead, for me at least, it tends to ooze out and form little bubbles of glue along the seam.

Could this be due to not enough/too much glue?

Aaron.

 

[melev]

Zephrant, by now you might have found some of my other posts/threads talking about various things I've built. I do feel like I'm getting more and more successful as I learn more about working with acrylic, but this thread really helped me see it on a far more professional level.

I'm currently using a table saw and router for my work. Is there an inexpensive option rather than buying a jointer? I'm not pleased with what I am able to run on my router table, so instead I secure my piece to a piece of MDF with a good edge, and using a straight router bit with a bearing, I run my edges to get a good surface. Is my next best option to simply sand the edge, and if so, what grit sand paper do you suggest?

I'm currently using a piece of MDF as my surface for gluing my pieces when I build sumps, and use Weld-On #3 with pretty good results. I do see some tiny bubbles, and have found sometimes I can simply lean the piece away from me a few degrees, run my bead of glue and then right the piece to 90 degrees again to give me a mostly bubble free seam.

Great tip on the speed squares! I've been wanting to make a template to hold my two pieces where they butt together at the top temporarily while the glue cures, but haven't made anything yet.

Marc

 

[Zephrant]

Aaron- It does ooze out each size. I'm not sure why you are getting the bubbles though. What is the temperature and humidity? Lately I have been gluing in a room that is 65 degrees, and pretty dry. I've heard that damp air makes it harder to glue.

Melev- Hey- I learned a ton from Acrylicman (and JabberJaws) from here, just passing on some of their information along with things I stumbled on myself.

I have not been using the Jointer as much anymore- Only for large sheets, and I may stop doing that. It is a cheap jointer (Harbor Freight) and it is pretty hard to get it setup so it is perfect. I normally get triangular pieces out of it when I run a square though it. Makes it a PITA to make a square tank out of them, but I have high hopes of making a pyramid some day, hopefully on purpose.

Great tip on leaning the piece BTW- I've heard that from several people, but I don't use Weldon #3 so have not tried it. I may have to though, as I'm thinking of dropping the #16 as it is not as strong.

My router is on the table saw- (Love the new Dewalt 618PK BTW!) Here is a sneak peak at a future write-up:

Note that the flush trim bit is high enough that the bearing does not touch, and the feather boards are adjusted to hold the work against the table-saw fence. Rough cut the work on the saw first, and take off no more than 1/32 of an inch to true it up.


Zeph

 

[aajenki]

Zeph,

I was not clear with my use of words. I actually meant bubbles of glue (not air) as opposed to a bead like you described.

But that brings me to another question.

That last beckett and venturi skimmers I build using only Weldon 3. Once done I felt that the welds we not strong enough so I ran a bead of Weldon 16 around all the accessible joints. I ended up with a nice concave bead around each joint (like you get on a glass tank is you uses silicone and run your finger along the joint).

However, by the time it had dried a bit (say 10-15 minutes) a row of tiny bubbles had formed inside the bead and an all beads???

I showed the local acrylic manufacture but he had never seen it before.

Any ideas?

Temp. would have been around 20-25 degrees C (68-77 degrees F) and not too humid.

Aaron.

 

[Cheapreef]

Zeph,

I was not clear with my use of words. I actually meant bubbles of glue (not air) as opposed to a bead like you described.

But that brings me to another question.

That last beckett and venturi skimmers I build using only Weldon 3. Once done I felt that the welds we not strong enough so I ran a bead of Weldon 16 around all the accessible joints. I ended up with a nice concave bead around each joint (like you get on a glass tank is you uses silicone and run your finger along the joint).

However, by the time it had dried a bit (say 10-15 minutes) a row of tiny bubbles had formed inside the bead and an all beads???

I showed the local acrylic manufacture but he had never seen it before.

Any ideas?

Temp. would have been around 20-25 degrees C (68-77 degrees F) and not too humid.

Aaron.

Last skimmer i built i did the exact same thing. Got the same results as you did, i'm going to say solvent poping. Get it sometimes in painting, when the top skim dries faster than the bottom and forms pockets of solvet.

Clinton

 

[Rad]

router setup

router setup

Zeph

How is that router mounted to your table saw? I've been looking at router tables and all seem to small to do most jobs. Using the rip fence of the table saw looks like a great idea. Could you explain how you did that?


Thanks

Rad