Acrylic Fabrication Q & A

[Turbo's Aquatics]

I am very active on a similar mega-thread elsewhere but I couldn't find an active one here on R2R.

@Troylee started the Acrylic 101!!!!! thread a while back, but it doesn't look like he's very active here anymore. Maybe this thread will suck him back in, he has great advice.

SHORT CUT LIST

Relocated short-cut list from a subsequent post to here, this will be kept updated for quick reference. When the text changes to a link, that means I've written the section. I will also try to keep this updated with links to useful posts by others as well, as a few other fabricators have chimed in with some very good tips

Solvent Welding (Pins method)
Solvent Welding (Capillary action)
Planning the parts
Overage for fillets
Bonding order
Curing time between steps
Rough cutting
Squaring
Edge preparation
Joint preparation
Applying the solvent
Flush trimming
Rounding and polishing
Curing time for finished build
Silicone bonding Acrylic to Glass

Then some other non-build related topics for me to rant about:

Stands for acrylic tanks. They need to be flat, and no you don't NEED to put foam under an acrylic tank.
Sanding and buffing scratches; how to wear out your arms
Crazing; deal with it.
Cracks; they suck and your tank will be ugly now.
I found a used acrylic tank, should I buy it? Yes! or no. But, maybe.



Just a bit about me, I started into acrylic fabrication when I wanted to build my first Algae Scrubber. It was my Dad actually that built my first 2 units, he still works with acrylic but in a totally unrelated industry, he makes display cabinets and holders for antique dealers and collectors, so he uses a lot of 1/8", 3/16" extruded and does everything via capillary action.

Once I understood the basics of acrylic fabrication, I started out strong out of the gate and built my own router table in 2011: 48" x 96" with a Bosch router mounted under the table

I did some small projects to cut my teeth

30g rimless sump

18g biocube sump

30g Sump w/fuge & ATO

40g frag tank with BeanAnimal overflow

40g Sump Fuge

30g Frag Display/Sale tank (I've made many of these)

50g frag tank: this is actually an Tenecor 120g that I cut in half lengthwise and bonded on a new bottom. For the record, I would not recommend doing this, honestly it would have taken less time to build a brand new tank.

62g Frag Tank

70g sump for FW

More to follow

 

[nervousmonkey]

[Edit: Removed]

 

[Turbo's Aquatics]

This one ranks up there on my most complicated builds list: 120g FW sump (sorry for fuzzy pics)

I made removable media baskets for this one

Perpendicular components always wreak havoc with assembly. This is what I mean by "complicated build"...

How much do you charge?

This is not a thread meant for advertising products/services. It's a Q&A thread in the DIY section.

 

[shovelhead]

What material did you use for the surface of the router table?

 

[TaylorPilot]

Looking good Bud! I have a similar router setup. Double laminated 3/4" MDF sheets.

What material did you use for the surface of the router table?

I believe it is probably just a sheet of white laminate counter top "Formica". You can apply it with contact cement, and is fairly durable. It also has the added benefit of making the pieces slide over the surface allot easier than the unfinished MDF top.

Or it could be this:

http://www.homedepot.com/p/Unbrande...ctual-750-in-x-49-in-x-97-in-461877/100070209

This has a top already added to it, but is more of a chip board, not MDF. Probably a little cheaper and would work just as well in most cases.

 

[TaylorPilot]

I also had a thread I started asking about tools for working with acrylic. It kind of morphed into the building of a prototype of the current model I sale. I also put up some pictures later on about sanding and buffing out corners. They looked amazing, but are messy and pretty time consuming.

https://www.reef2reef.com/threads/tools-for-working-with-acrylic.148014/

 

[nervousmonkey]

You make some seriously good stuff. Congrats on learning how and doing it. Wish I knew what you do!

 

[dbl]

@Floyd R Turbo, thanks for starting this thread. You’ve got some serious skills there and it’s great you’re willing to share with the community. Timing isn't bad either as I'm in the planning process of building a new sump! I will be following along for inspiration!

 

[Turbo's Aquatics]

Ok so those are a few examples of the kind of things I've built. I posted those just to show my personal experience level with acrylic fabrication. The assembly techniques required for complicated builds have all been a learning process, and while I haven't learned it all, I've learned enough to answer just about any question you can throw at me.

The short list of things I haven't done, but have a good level of knowledge on:

Bonding 2 sheets together end-to-end (butt joint) using Weld-on #40 or #42
Acrylic thickness over 3/4" (I don't build tanks, I am a strong believer in glass tanks)

Now, to go into the process itself. I'll break this into a series of posts, because there are a lot of things to take into consideration.

There is a lot of information out there on the interwebz and a lot of YouTube videos showing you how to build a full size tank out of 1/4" acrylic with saw-cut edges, capillary action welding, and black electrical tape. Ignore that %$#@ unless you enjoy a house full of water. Just because some guy in a video did it doesn't mean you should. I'll show you how to avoid the mistakes that are most common. Hint: everything in the first sentence is a big mistake.

The first thing to cover is material.

Plexiglas is a term like Kleenex. Kleenex is tissue, but not all tissues are Kleenex. Plexiglas is a brand name, not all acrylic is Plexiglas.

There are also different types of plastics, the most common ones you will find are Acrylic (extruded and cell cast) and Polycarbonate (commonly called Lexan, though that is also a brand name).

Polycarbonate is not something the average DIYer will be able to use. First, it is "grabby", meaning if you try to cut or route it, it can bind and throw the piece. This is generally bad. So my advice is to just avoid using it.

Acrylic types are generally Cell Cast and Extruded.

Extruded is exactly how it sounds, it is formed by extrusion and therefore you can usually see the lines on the surface of the material. This makes it less "show quality" but it is still fine for many small applications, as well as sumps and small frag tanks. Extruded acrylic sheets are typically masked with plastic, but sometimes are masked with paper. It is generally more flexible and will bow more easily, so if you have a sump with many baffles and there is not a long open section, extruded can be just fine. For sumps with large open sections, you will want to bump up a size (or two) which usually makes it the same price as using thinner cell cast. Not for use with full-size display tanks. I personally use it very sparingly, if at all.

Cell Cast is formed either in vertical molds or flat molds. In either case, you will usually end up with variations in thickness within the sheet itself. A vertically molded sheet can be slightly thicker at the bottom. A horizontally molded sheet can be thicker on the edges and thinner in the middle. Usually this is pretty difficult to notice unless you cut a sheet up into equal sized pieces and then stack them up in 2 stacks side by side - then, it becomes very clear. It's worth mentioning because it's not always possible to get everything dead on exact with a micrometer when working with acrylic. Fortunately, acrylic is pretty forgiving as long as you follow a good preparation and assembly procedure. Cell Cast acrylic is almost always paper masked.

The second thing to cover is brand: this is my recommended list in order of the best material to use

#1 is Spartech Polycast. This is what you see being used pretty much exclusively by ATM and a few others. Polycast is imperial thickness, meaning, when you order 1/2", the thickness is actually 0.500". It is also (I believe still) made in America and is wicked expensive. So, for the average hobbyist, this is usually out. But also, you mainly woudl consider this when building a tank and not a sump or an ATO box, etc. It comes in oversize sheets, 50" x 100" instead of 48" x 96", so it's easier to make an 8' tank be truly 8' long. You can also get in 10' sheets. $$$$

I believe most Polycast is cell cast. It is also the brand that is used to make fighter jet canopies (at least it was last I heard)

#2 is Plexiglas brand. Made by Arkema, you might also see the name "Altuglas" on it. Thickness is metric, so when you ask for 1/4", you get 0.236", 3/8" is 0.354", 1/2" is 0.472", you get the idea. Comes in 48" x 96" sheets, but usually they're slightly more (like 46.125 or 46.25, etc)

Plexiglas cell cast is generally called "Plex-G" or sometimes "GP". It has a paper mask with green print on one side. There is also a generic cell cast version which has a paper mask and no print on it, but it is still an Arkema brand, sometimes referred to as "General Purpose" or PMACS (or maybe PMAX, sounds the same). Not necessarily the same as "GP" so you have to be careful.

Plexiglas extruded is generally Plex-MC, but different suppliers have different terms. It also has a printed paper mask.

I use almost exclusively General Purpose/PMACS Arkema Cell Cast, but nothing I make is "show" quality. No display tanks. PMACS is cheaper and is almost exactly the same as Plex-G. It's kind of like when a PC processor manufacturer makes a dual-core and quad core chip. They actually only have one line, and if a quad core chip has one or two cores that don't pass, they turn them off and presto! Dual core chip without a second factory line (which is why you can unlock cores in an AMD chip). Not an exact parallel and maybe not 100% technically correct but that is the concept. Arkema plain-labels sheets to compete with other generics. They're actually made in the same factory, same line. There's just no warranty on it.

Sidebar on warranty: warranty only matters if you buy $100k of material from them a year. Then, and only then, will they comp you if you find a flaw after the tank is built and you tear off the mask. For the average hobbyist, you would (literally) have to remove the entire mask and examine the uncut sheet for flaws in order to qualify for a warranty replacement. Then if there were no flaws, you would have to put the mask back on to work with the material (or re-mask with a new mask). Good luck with that! The Plex-G warranty is as valuable as dog poo in a box to the average hobbyist. Actually that goes for just about any acrylic manufacturer warranty.

#3 is Acrylite brand. Made by Cyro, also metric. This used to be one of the solid standby brands, then a few years ago most of it started getting made in China and it was "off the list" for a while. However I know a few builders you use it and like it just fine still. Thicker material (over 1") is still made in Germany I believe.

Call Cast is Acrylite-GP. Extruded is Acrylite-FF. Both have paper masks with red print. I am not aware of a generic cell cast version of Acrylite.

That's really it. There are others but I don't recommend using them for pressure vessel applications.

If you are building something that is not required to hold water in the same manner, then just about any brand will work fine. What I mean is things like a filter sock holder, probe holder, or a drop-in anything.

The thickness of the material needed is a direct function of the water column height. That's another post.

 

[Turbo's Aquatics]

What material did you use for the surface of the router table?

Looking good Bud! I have a similar router setup. Double laminated 3/4" MDF sheets.

I believe it is probably just a sheet of white laminate counter top "Formica". You can apply it with contact cement, and is fairly durable. It also has the added benefit of making the pieces slide over the surface allot easier than the unfinished MDF top.

Nailed it

2x 3/4" MDF glued together, full sheet of formica bonded on with spray adhesive.

I actually mounted the router to a metal plate embedded in the top sheet, but I wouldn't do it this way again. It's showing now, the table is pretty close to being useless because of this. I get all my parts CNC routed now at a local sign shop.

 

[Turbo's Aquatics]

I'm going to try and pic away at all the concepts a little at a time. feel free to post any questions, but the thread will probably jump around a bit if you are trying to follow it in the future!

 

[TaylorPilot]

That's all pretty much spot on with everything I have read and researched. Only thing I would add is the Chemcast brand of acrylic. They make cast acrylic. I know several of the more popular sump builders use it for their sumps, and it is one of the only brands that offers the neon colored acrylics. It is a tiny bit thinner than the Arkema, but for sumps and stuff it works fine. I use it for the smoked outer boxes, and the Arkema General Purpose for the black internal boxes. Atleast in Houston, it is easier to find the Chemcast in different colors. The Arkema I can usually only get if I get it in clear, black or white. Anything else, i have to order a full 50 sheets and it takes 6 weeks to get in.

 

[Turbo's Aquatics]

Chemcast is actually on many tank manufacturers' blacklist. Google it. There was one company making really inexpensive tanks with Chemcast years ago, until they all started exploding. Maybe they have fixed the problem...but...

 

[TaylorPilot]

Well I wouldn't build a display with it, but it works fine for sumps and smaller projects. I have seen that some popular manufactures like Synergy use it almost exclusively. It machines and glues allot better than the cheaper cast stuff from overseas (acrystar). I had reservations about it also, but after using it for awhile and talking to some other fabricators, it works well. At least with the smaller boxes and products I make. The only difference I can see between it and Arkema visually is that it is a tiny bit thinner. The price is about the same (within $5 of the Arkema brand), but is the only one locally that is available in an array of colors. I imagine that is why the sump manufactures use it in their colorful sumps.

 

[Turbo's Aquatics]

When you have your tank professionally built, a failure is usually a material defect, a manufacturing defect, or an installation/foundation issue.

When you build your own tank, you inject a whole host of potential failure avenues, mainly related to the manufacturing steps. There are a lot of things that you want to do right or more accurately, avoid doing totally wrong, such as edge prep, squaring, your solvent welding technique, removing sharp edges, time between steps, etc etc.

That's probably a good disclaimer to have in this thread so there it is. Not meant to scare anyone away from working with acrylic, because it's not really that bad once you know a few of the snazzy tricks that are out there.

Material Thickness

For pressure vessels (anything meant to hold water) there are several different opinions and calculators out there that can be used. I've had several discussions with James Steele with Envision Acrylics about these calculators, and the issue is that they are based on 2 scenarios: a closed box (6 sides with no openings) or a rimless box (obviously, a 5 sided box, open on top).

Issue #1 is no one builds an aquarium without an opening on the top. That's kind of pointless...but that's how those calculators figure things, otherwise they would have endless combinations of eurobrace configurations to deal with.

Issue #2 is that many tank manufacturers have challenged them on the factors and calculations that they use, and have pointed out that in the real world, one of their calculators oversizes the material requirement, while the other one undersizes it. I can't remember which is which though. But they won't change their calculators, something to do with the potential for liability, blah blah blah lawyers probably won't let them do it.

Here is my general philosophy. I try to stay conservative.

Minimum material thickness: 1/4" (0.236). I never use anything thinner, anywhere.

Preferred material minimums: 3/8" (0.354) for vertical exterior walls, 1/4" for top and bottom panels. For interior baffles, 3/8" for pressure baffles (water level is different / lower on one side), 1/4" for non-pressure baffles.

Display Tank Material Thickness

This general guideline is what James relayed to me as his personal guideline. I believe these are based on Polycast, which is imperial thickness (1" = 1.00") so keep that in mind when using a metric-based material.

For a EUROBRACED tank:
24" high, use 1/2" minimum
30" high, use 3/4" minimum
36" high, use 1" minimum

Eurobrace minimums:
3" perimeter eurobrace on any tank.
6" wide crossbrace for every 24" of tank length.
1.5" radius for all interior corners of the eurobrace cutouts (3" diameter circle). This is very important.

For instance:
A 48" x 24" tank (footprint) will have 3" perimeter eurobrace and a single 6" crossbrace at 24".
A 72" x 24" tank will have 3" perimeter eurobrace and a two 6" crossbraces, one at 24" and one at 48".

At 8' length, it's recommended to jump up one material thickness* to keep deflection down.
* I need to clarify with James if he was referring to the euro, walls, or both. I believe, both.

There are times when someone's lighting scheme doesn't match the above formula. For instance, if someone wants an 8' tank but only 3 cutouts in the top - in such cases, increase the perimeter eurobrace width from 3" to 4.5" and increasing the crossbrace(s) width from 6" to 8".

James claims:

I've been using this formula, 1.5" radius corners, and material thickness minimums above, for many years and I have *never* had a tank fail.

So that covers the basics of material thickness, for tanks.

For sumps, most people look at a sump and think "that's only going to be half full the majority of the time, so I don't need to build that to the same level of strength as a display tank". My response to that would be "maybe". But it depends on your worst case scenario. Think about it this way, if you underbuild your sump to save 25% on the material cost, and then you have a long-term power outage where your sump sits at the highest level for potentially days, is that when you would be OK with a failure occurring? Because that's when it's most likely to occur. I think it's rather ridiculous that someone would spend thousands on livestock and equipment, but have no problem going with thinner material on the lifeline of their filtration system if it saves them a couple hundred bucks (if it even costs that much).

As I mentioned above, my standby material is 3/8". Most sumps have baffles, and if these are welded in place before the top/bottom are added, then they are structural members and you can effectively treat each chamber as a sub-tank. At least that's they way I think of it.

Most sumps are not over 18" tall, at least, I haven't had many requests for one that large. Unless you have a large open expanse (like longer than 24") or a need for a sump taller than 18", I build with 3/8" walls.

I personally never build a sump with 1/4" walls unless it's something really small, like a sump for a biocube. I know..."but I saw this really nice looking XYZ brand sump with 3/16" walls and it was super cheap and like 40 gallons"...and if it fails, you're seriously screwed. Granted that most mass-manufactured sumps (at least from reliable manufacturers) are going to be done with precision cut material and well-trained technicians - so take that with a grain of salt. If you have a manufacturer that has a good reputation and assures you that what they build for you is adequate, go with that. If you are looking at the lowest price online super duper cheapie sump that you can get away with, you are going to get what you pay for. This guide is really more for the DIY crowd, so slightly over-building something is in your best interests.

Where's the soapbox emoji when I need it? Ok I'm off it now.

 

[dbl]

Great...as usual, a day late and a dollar short :mad:. @Floyd R Turbo...I've ordered 1/4" cast (on the truck and being delivered tomorrow) to build a sump where the main section will be 33 x 16 x 16 (L x W x H). It will have what amounts to four baffles running the width of the sump and I was planning on Eurobracing the top. A separate refugium at 14 x 16 x 22 (L x W x H), again, Eurobraced on top. And finally an ATO reservoir at 16 x 16 x 24 with a complete top (with exception of access hole/port for filling and cleaning). I did base this decision (possibly a stupid move on my part) on looking at numerous XYZ brands built using 1/4" material.

Judging by your comments/guidelines above, I've screwed up and ordered too soon! Obviously I'm building this at my own risk, but any thoughts on the chances the 1/4" material will work with the given dimensions above? Or have I backed myself in to the classic do-over scenario? Your thoughts will be greatly appreciated - unless you tell me to reorder (just kidding).

 

[Turbo's Aquatics]

I would not re-order the material. This is just my personal philosophy, mainly because the price difference (for me at least) between 1/4" and 3/8" sheets is pretty negligible in the grand scheme of things, but I've got a pretty good hook up. My best price suppliers are minimum 120 miles away, but the shop in town that has the CNC also has a top-rack flat storage space and they just lump on my stuff on to their orders and we split the shipping which is up to a full pallet for something like $100. Then, for a full sheet of PMACS 3/8" is usually $165-$180 and 1/4" Plex-G is $130-$150, so if I can build a sump out of 1/2 sheet worth of material, it's like $15 difference in material cost. So it just makes sense, for me, to build out of 3/8".

For 33L x 16H you're fine with 1/4" especially with 4 baffles.

For the ATO, is that 24" tall?

 

[Turbo's Aquatics]

An addendum to that: you will just want to make sure that your solvent welding technique is correct. If you do capillary action welds, I would worry about the joint strength of a 16" tall 1/4" build. The thing that mandates the thickness of the material, as long as the welds are good quality, is the water column height it has to hold against.

It sounds silly but the thickness requirement for a 24" x 24" tank that is 1" long (1" front to back) is the same as a 24" x 24" x 24" tank. Or a 24" x 24" x 12403254324" tank. But the 12403254324" wall would probably need to be a bit thicker.

 

[Turbo's Aquatics]

Let see...sections to come...

Moved to the OP

 

[dbl]

Thanks for taking the time to respond...

I would not re-order the material....For 33L x 16H you're fine with 1/4" especially with 4 baffles...For the ATO, is that 24" tall?

Yes, the ATO is 16" x 16" box, 24" tall. I guess I could put an internal baffle of sorts, just leaving a few inches on the top and bottom (to allow it to empty equally), if you think that would help.

An addendum to that: you will just want to make sure that your solvent welding technique is correct. If you do capillary action welds, I would worry about the joint strength of a 16" tall 1/4" build. The thing that mandates the thickness of the material, as long as the welds are good quality, is the water column height it has to hold against.

It sounds silly but the thickness requirement for a 24" x 24" tank that is 1" long (1" front to back) is the same as a 24" x 24" x 24" tank. Or a 24" x 24" x 12403254324" tank. But the 12403254324" wall would probably need to be a bit thicker.

I will be following along to make sure my welds are of good quality! Funny thing is I was originally of the mentality that it will "normally only have about 10" of water in it". That is until I read your post above...didn't even consider an extended down time when it will be holding several additional inches.

I was planning on using the pin method, but I may hold off on building it until you finish this series...lol.