Acrylic Fabrication Q & A

[Turbo's Aquatics]

We build sumps here and was wondering what solvent you all have been using?

Methylene Chloride with a 2%-5% addition of Glacial Acetic Acid is the best mix. You increase the Acetic Acid due to humidity to prevent blushing (white residue) around the bond area

I typically use 5-7% AA FWIW. I didn't think the AA did anything to help with humidity, that always happens to me when bonding in high humidity regardless of AA concentration. It was my understanding that only EDC (Ethylene Dichloride - nasty stuff) was the thing that solved the humidity problem. 15% EDC 5% AA 80% MC I think was the James mix. But EDC is the $ and dangerous stuff, comparatively.

I stopped using packaged solvent years ago due to low bond strength. The lowest bond strength was with Weldon 40 and 42 in our tests.

Thanks for sharing that. What's funny is Cyro will tell you the opposite, but after I spoke to a guy there who had 30+ years industry experience, I asked him how long he let the solvent joint cure and if they used the pins method, I don't recall the answer on the pins method but they only let the solvent joint cure for part of a day IIRC, it definitely wasn't what James recommends for full bond strength for testing purposes which is around 72 hours for 1/4", a week for 3/8", 2 weeks for 1/2", add a week for every 1/4" after that.

Have the edges sanded with 60 and 120 grit sandpaper. A few more passes with some finer grit sandpaper and me and the local who has done this stuff before will attempt a rebuild.

Sanding rounds the edges and leave tiny voids that can cause bubbles to form. You will want to scrape the edge flat with a razor blade. It is especially important to get the edge square because rounded edges of an off-square edge will allow air to entrain as the solvent evaporate, and a fillet won't properly form to prevent it with rounded edges.

 

[Lowell Lemon]

Floyd R. Turbo,

I live in a low humidity area but during certian times of the year we have enough humidity for blushing near the seams. I just increase the Acetic Acid to 5% and it goes away. I depended on a Chemical Engineer for the formulation and rates. It has worked so well for us...since 1988. I guess there has been some luck with our methods over the years...lol.

Pins method alone is not indicated with the Weldon 40 or 42 if you read the Cyro fabrication outline (at least the old one I have) instead the use of a 2 degree or 3 degree bevel is recommended so a fillet bead remains inside the bond area.

In our test samples we allowed in excess of 72 hour set with the recommended 2 to 3 degree bevel on the parts butted end to end or to a 90 degree joint. Then we applied impacts and found a clear clean seam seperation in the joints. I was about to construct (8) 16' panels in 1 1/2" and 2" material with butt seams at the 8' mark and impact and pressure was a real concern. The customer was also unwilling to pay for a 24 hour annealing process in a large autoclave to increase both the bond strength and resistance to crazing. With a mix of the solvent mentioned we were able to have the parent material fail at about the same rate as the seam. I chose to use the solvent method in most cases after that. I did continue to use Weldon 40 or 42 for beveled joints like large Hexagon shaped tanks since it would provide some fill to compensate for seam flexure during bonding. All parts were custom cut with a CNC machine first with a trial dry fit before assembly using a custom bit for the CNC router.

Our test methods were not done in a proper laboratory but in our fabrication area so in all fairness some other factors may have been at play. But who wants seam separation due to some accidential impact with 1560 gallons of saltwater and 4000lbs. of reef rock behind the panel?

Love your new Algea Scrubber and need to get one from you someday when a larger tank is in the works or I may use it on a multi-tank central filtration system. The pictures of your product and the comments from customers indicate a first rate product. Congratualtions on a great product and great idea. I love seeing American Business innovate and improve. Well done sir.

 

[Turbo's Aquatics]

Pins method alone is not indicated with the Weldon 40 or 42 if you read the Cyro fabrication outline (at least the old one I have) instead the use of a 2 degree or 3 degree bevel is recommended so a fillet bead remains inside the bond area.

I was saying they didn't use the pins method for solvent welding - IIRC he said they just tipped the piece to create a gap, filled it, then closed the gap a few seconds later (no soak time) I was like...really?

 

[Triton Marine]

Have any of you ever used LuciteLux to build with? I had a call yesterday on a place selling it and the price was pretty good. I'm pretty happy with what I'm using though, but it doesn't hurt to shop around.

 

[Turbo's Aquatics]

Looks like Lucite's cell cast and extruded. Lucite is typically polycarbonate. No idea how good their stuff is

 

[Triton Marine]

Looks like Lucite's cell cast and extruded. Lucite is typically polycarbonate. No idea how good their stuff is

It actually was TPI....didn't know they are a sponsor on here. They have a local office here that has stuff in stock. The 1/4" was $30 less per sheet and $50 less per 3/8 for Lucite cell cast. Hmm might have to find more out.

 

[Lowell Lemon]

It actually was TPI....didn't know they are a sponsor on here. They have a local office here that has stuff in stock. The 1/4" was $30 less per sheet and $50 less per 3/8 for Lucite cell cast. Hmm might have to find more out.

Just remember to make sure you were quoted the Cell Cast and not the Continuous cast or extruded. Only Cell Cast is of the quality necessary for sumps and aquariums. The extruded and continuous cast adsorb more water than Cell Cast. And remember you often get what you pay for...cheaper is not always better.

 

[Triton Marine]

Is anybody using a fixed fence for the router? I need to purchase a new fence, but just deciding on what to go with.

 

[vladandlilith]

I use an air powered angle buffer.

 

[Lowell Lemon]

Is anybody using a fixed fence for the router? I need to purchase a new fence, but just deciding on what to go with.

I use a fence and posted a picture on this thread [HASHTAG]#133[/HASHTAG]. Take a look and see what you think. Use a 1/2 two flute plastic grind router bit from FTM Plastics...they have a website. It provides the best control for removal of saw cut edges ready to solvent weld. If you want to spend the money just buy a CNC machine and you should be ready to bond right off the machine. You might have to make a second pass on some machines to get a smoother finish. Edge Finisher Corp makes a edge polisher that will prep the edges and polish them. You can also use a joiner with spiral carbide blades to achive a finish ready for bonding.
Quite a few options out there.

 

[Turbo's Aquatics]

I use a fixed fence opposite the bit and pass the sheet between the two. Mine is a 4" wide piece of 1" black acrylic (actually 2x 1/2" bonded together) that I refer to as the Black Mamba

Can't get this to embed but I think this will open the vid in a new window ooooh I figured it out!

 

[Lowell Lemon]

@Floyd R Turbo
Just watching you do that hurts my fingers. I just spent $1000.00 for an ER visit and three stitches when my finger just touched a saw blade. Hope I never do that again. By the way one small twist and the kickback may impale you. I had some polycarbonate kick back and impale a wall about 5 feet behind me once. I was gun shy for a long time. Be careful and don't teach others our bad habits.
Lol.

 

[Turbo's Aquatics]

like deez?

 

[Lowell Lemon]

Mine was much cleaner and now it hurts again...lol. I think you should try the fence design I use and a couple of hold down pads or push sticks. I also have a power feeder for those small acrylic strips...keeps the fingers out of the way.

 

[Turbo's Aquatics]

Meh. Done tons of stuff this way, It's very much all about the technique. The pic above was pure stupidity. I had sandwiched 3x 3/8" pieces into a cube and was routing it so that 3 sides were perfectly square. It was a corner block in a sump I was fixing using triangle rod and weldon 40 and I needed something in the corners. So I was holding on to it on the leading and trailing edge with one hand (tightly) and trying to also keep it flat in the table while holding it against the fence and sliding it. I did just fine with the first 5 of them, the last one got away. You never forget that sound of the router motor bearing down as it chews and spits what feel like red hot acrylic shavings everywhere. I still have the cube as a reminder. I should go find that.

I also wear a full facemask whenever I'm routing. What I need to get is one of them leather or better yet kevlar aprons. I'm not so much worried about the plastic shards as I am about snapping a bit. I have a buddy who still hasn't found one of his shattered bits.

 

[Triton Marine]

I use a fixed fence opposite the bit and pass the sheet between the two. Mine is a 4" wide piece of 1" black acrylic (actually 2x 1/2" bonded together) that I refer to as the Black Mamba

Can't get this to embed but I think this will open the vid in a new window ooooh I figured it out!

Doing it this way wouldn't you have to move the fence a lot? Right now I use a joiner but thinking of using the router sense I use it all the time. The joiner does a great job but one less tool equals more room.

Lowell...how did you make your fence again?

 

[Turbo's Aquatics]

Yes but it's very simple, loosen one c-clamp just enough to nudge the fence a but then make next pass. This way ensures that the edges opposite one another are perfectly parallel. There's no other way to do this reliably IMO

 

[cromag27]

For a long time I would use an offset fence on a router table. it was a pain to adjust. Now I just use a straight fence and route on the other side of the bit, same as turbo. much more accurate.

 

[cromag27]

This is how I test my bits for sharpness.

 

[Lowell Lemon]

Doing it this way wouldn't you have to move the fence a lot? Right now I use a joiner but thinking of using the router sense I use it all the time. The joiner does a great job but one less tool equals more room.

Lowell...how did you make your fence again?

I cut a fence that is about 1/32" smaller on the infeed side than the outfeed side and attached it to an 8' table. If you look at post # 133 you will see the picture of the fence. I used a table saw to make the cuts for the fence with a holesaw to make the hole where the vaccum pickup and router comes up through the bottom of the table. Each end has a routed slot that allows the fine adjustment of the fence to the router bit. Most two flute router bits have one flute longer than the other for some reason. I adjust the fence so that the longer flute just scrapes a precision ground flat edge as I turn the router bit by hand in a reverse direction to the flat edge. The flat edge is tight to the outfeed side of the fence. So I am removing the exact amount of material as the infeed fence allows (about 1/32"). I set up my saw fence on the table saw and panel saw to cut 1/16" more than the finished parts so that two passes on the router fence leaves me the exact size I want. In production you should use batch cutting to get all your parts to fit. This means I set the saw fence once for each cut (all 12" cuts let say) and then all my parts fit for each batch run. If I have to run more parts I am within at least a 1/32" or 1/16" of an inch and just have to make more or less passes in the router fence to get an acceptable part. I can take more pictures if you like. Batch cutting saves lots of time since you cannot set a fence visually the same way each time. I have use a DRO (Diigital Read Out) for years as well but the accuracy is only .005" so you do get some machine error each time you set up a cut. That is why batch cutting is such a good idea for repeatable results. I also oversize the front, back, and top and bottom panels of a typical aquarium so that I can flush trim with a bearing on the end of a router bit (flush trimming bit) that I by from FTM plastics as well. The right grind on a carbide router bit makes all the difference in preventing chip melt on to the acrylic parts you are flush trimming.