Acrylic fabrication: a how to (dail up sensitive)

[sumphead]

I get often asked questions about acrylic and building techniques. So, I thought I would take the liberty of posting a step by step pictorial of a project. I had a little over 1/4 sheet of 3/8" continuous cast acrylic and decided to make a 15 gallon acrylic cube tank. I hope you all enjoy.

Cut list:
(2) 15"X15"
(2) 14.25"X15"
(2) 15.25"X15.25" (top and bottom)

Cuts should be as square as possible. I use a standard 10" table saw, then a jointer to make smooth edges. A router can be used to smooth out the edges as well with a fence or guide. Since I have a jointer it just easier for me.

Only the sides are pictured as the topr and bottom do to need to be ran through the jointer (explain later)

The first step is to assemble the all four sides. The reason for this is you don't want to attach the sides to the bottom only to find one of your cuts not square causing a stress point on one seam. It also makes it easier to flush cut an oversized bottom on a router table (reason for not jointing the top and bottom)

I attach the sides to the front using a square weighted jig I made from 3/4" pine. Pine is soft and less likely to scratch the acrylic.

Generally the weight of the acrylic with the clamps on the jig are enough to ensure a bubble free seam. However since this tank is rather small I had to use bar clamps to keep a snug seal. I use weld-on #4 as my primary solvent. It is slower than #3 allowing for small adjustments after application. #3 tends to bond almost instantly.

that's boxter's sump in the background. all four sides.

There are several methods of actually applying the solvent. In this case the capillary method is preffered by me. The "pins" method is for another post generally applies to larger projects.

Now for the Euro top. Draw out your Euro top on the piece. Do a rough cut out so your router blade does not have to work so hard when making the final cut. I use a flush trim bit on a homemade router table. My router is a Porter Cable 1 3/4HP with both 1/4 and 1/2" collets. Then use a strait egde or a wooden jig (in this case more scrap acrylic) and use a strong double sided tape to hold the jig in place and use your flush cut bit to cut out your euro top.

after drilling a stater hole of course.

Corners for larger projects are a little trickier, but still not too hard. I intentionally made this Euro brace somewhat small as I do not know the application of this tank. Users would need a bit smaller brace for hang on applications. In this case it is a 1" brace with a little less that 3/4" in the back just for this purpose.

The top and bottom are attached and weighted. Generally all seams require at least 1 hour to cure before moving. I prefer to wait 2, but sometimes you just cant (like when you wife is yelling at you 'cause she cant park in the garage 8O )

As you can see the top and bottom are slightly larger than the sides. This is so you get a good solid bond and is easily trimmed up with a flush cut on the router.

All that is left is to clean up the edges and polish. I am by far no proffesional and this project is not perfect (like everything else I do) but it isn't rocket science and doable by all.

I'll post more picture when I have it all cleaned up. There was a similar post on "the other site" but my methods are a bit different and I thought I could simplify it a little.

Hope you Enjoy

R-

 

[bound_for_obx]

Thanks for the tutorial Sumphead. I want to make an overflow sometime soon and my search for acrylic working techniques hasn't been very productive.

 

[yaksplat]

Nice work

 

[WarOrks15]

sticky i think!!!!

 

[lmw80]

ok, this is a great informational source and has been sticky-ized!

Thanks sumphead!

 

[sumphead]

No sweat! I am glad to do it. Again I will post the cleanup process as well fairly soon. I will do my best to answer any questions.

 

[bound_for_obx]

Sumphead, I think that I picked up somewhere that you need to use the "continuous cast acrylic" like you said you are using. My local Lowes carries "Acrylite" and calls it plexiglass. Is this the right stuff? Where do you recommend getting the weldon #4 and #16(?) I also called a local glass place and they said plexiglass is what I needed but this doesn't sound right.

 

[sumphead]

There are three types of acrylic: Cast, Continous cast, and Extruded. The difference betweem them is the process in which they are made. They have different densities as listed respectively above. Cast is the strongest as it is most dense. Extruded is the weakest as it is heated to a higher temperature then, well extruded into sheets. All are stong and have thier uses. Proffesionals will not use extruded for tanks (and for large tanks, I agree), but smaller projects it is just fine. Acrylite is a great manufacturer that makes all of the above. Acrylite GP and GT are Cast. Acrylite FF 1/4" and thinner are extruded, FF 3/8" and above are continuous cast, which is somewhere in the middle. For sumps, I have no problem with extruded. For tanks I prefer the 3/8 continuous cast for cost and ease of use. Plexiglass is a generic name for acrylic, though there is a manufacturer who uses the name. There are several manufacturers but Acrylite is most common in the US.

Look under the Yellow pages for Plastics, Plastic manufacturers, and sign shops. Most will carry Weld-on as well as acrylic sheets cheaper than Lowes and HD. Just be advised while these places have extensive knowledge of thier plastics, seldom are they up to speed for water uses.

What are you planning on building?

R-

 

[bound_for_obx]

I'm planning on building a hang on back overflow. I think that one of them Cast, Continuous Cast, or Extruded was meant to be better for heat forming. In retrospect, it may have been Extruded, I just can't remember or find the link.

 

[sumphead]

Again, the differences are they way they are made causing density differences between them. Extruded would be easier to bend because it is less dense. Also because it is less dense seams are not as strong which is why it sould ot be used for larger applications. For an overflow box 1/4" extruded is just fine.

 

[sumphead]

The clean-up

OK, after flush cutting all of the edges on a router-table (or with a hand router), I use a razor blade to gently remove any burrs from cutting and beads from the seams. When you put solvent in a joint and put pressure on it tidbits of solvent ooze out of the joint. This is normal. They dry as beads on the outsides of your seams. Then I start the elbow grease; I first do a quick sand with 300+ sandpaper also along the corners to ease them as they are very sharp. I follow up with a good wet-sand with 600+ grit on the seams and over any solvent that may have dripped on the project. I sand sand sand till smooth. I then buff out the scratchmarks with a buffing wheel and a plastic compound. This compound can be found at any plastics place.

After a lot of buffing with not only the wheel but a soft cloth you end up with a ridiculously clear new acrylic tank...

Keep in mind the "clean-up" is completely optional and only for looks. The tank is structurally sound when the solvent is cured. Typically I wait at least 3 days before water testing and a week is recommended. If per change you have a small leak you can fill with Weld-on #16 as you would silicone on a glass tank. It takes away from the beauty of sharp edges and can be messy, but sealed with #16 and leaks are gone. This particualr tank was overbuilt as 1/4" acrylic would have been more than enough.

Just to give you a size reference here is an everage sized 4 year old kid-fish...

As a disclaimer I have to re-emphasize I am a mere hobbiest. These are the methods that work for me. If you have the tools (a table saw is really all that is required), a cheap source of acrylic, and some time give it a shot. It is very rewarding and fun tp play with. Just always keep safety in mind and Happy DIYing!

R-

 

[sumphead]

HEY BEARFAN, fix my typos....LOL

 

[Scottcenfla]

Mighty fine work Sumphead! Great work, great pics, you got it down with working with this material. I killed the thread I started and added the text here to the Sticky for what it's worth. Scott

There were some excellent suggestions on Eddie's DYI Sump Thread, I didn't want to threadjack his post, but I thought the subject worthy of a thread in itself. Being new here, I would guess this subject has been brought up before, I hope I'm not beating a dead horse.

I had mentioned that I was using a jigsaw with a fine tooth blade and it was working well with the 1/4 inch acrylic. I found that a 10 or 12 teeth per inch (tpi) was fracturing the thinner stuff. I chose using the jigsaw as the project I'm working on required several curved cuts. Still there was some melting back together behind the blade.

This brings to mind my line of work. I'm sure everyone has seen the overhead drive-in bank units that sends the carrier in to the tellers. Most often we use a 4 1/2" clear acrylic tube above the customer unit just to canopy level then switch to regular pvc and take it in the bank.

We always have to cut to fit these acrylic sections, I would say they are 1/4" thick, maybe 3/8ths at the most. The reason I bring this up, I found that a sawsall works well for this with a little practice. Cutting slow with a wide blade allows the blade to pull most of the heat away from the teeth, hence less melting.

We have also used a table "chop saw" like masons use for brick cutting for cutting the acrylic and pvc tubing. It works good on the pvc, but tends to make a rougher cut and takes more filing on the acrylic vs. the sawsall to finish the end smooth.

With the jigsaw and plate acrylic, I found that cutting fast at a high rpm produced less melting behind the blade. When that blade gets hot though, there isn't anything to do but let it cool off or it will melt the acrylic like a hot knife in butter.

Biggen, I haven't tried the fine tooth blade on the 1/8" acrylic yet or used a table saw nor have I tried the scoreing method. I would guess a table saw would work well, a large blade pulling more heat away from the cut plus a wider cut with less chance of melting back together.

Has anyone tried using a spray bottle of water ahead of a jigsaw blade to keep the temperature down? It might work, but I'm not a big fan of electric tools and water I'd love to hear some more ideas and experiences from the seasoned craftsmen here.