OP
OP
That’s not even a valid comparison. A 96” wide 30” tall tank with a full 3” or even wider perimeter euro with 6” wide crossbraces at 24/48/72 made from 1/2” will bow like a mf.
Acrylic Fabrication Q & A
- Thread starter Turbo's Aquatics
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My point is simple rule of thumb pat answers don't apply to all scenarios. If it is 24 then it must be xx if 30 then yy. If 48 then dd.
I don't disagree with you on many of your points. If you really want to see a disaster waiting to happen, there is a guy posting on planted tank about a rimless ten foot glass tank bowing. Now that would keep me awake at night
OP
OP
You have mention this “pat answers” thing several times. It’s odd. Because what I’ve said is up to 24” tall, 1/2”. Up to 30” tall, 3/4”. Up to 36” tall, 1”. These assume one piece euro with 3” perimeter and 6” crossbraces every 24”. If you want a width frame of reference, ok: start with 48” wide.
At 96” wide jump up one thickness.
these are not pat answers. Your example of a 96” tall column tank while providing an example of lack of bowing is completely meaningless in the frame of reference of the typical aquarium build. I don’t get what you’re trying to prove and honestly I no longer care
Want fewer openings? Thicker euro or wider perimeter/braces. That kind of thing is more subjective.
Cabinetman
Well-Known Member
One simple question. If you build a tank right now that is 96 long by 30 inches tall by 24 inches deep with a full eutobrace as wide as you want how thick is the material that you use? Or say an 8’x2’x2’ ? Not that I care really. But if you say 1/2” in my opinion you are using material to thin because it will bow and bowing causes seams to fracture. And although that tank might not blow out it looks terrible. I was actually into a pet store that has a 375 gallon that I built yesterday and I looked down the front panel to see if there was any Boeing at all and it’s still as straight as an arrow. And that didn’t surprise me because it’s only 24 inches tall and I used three-quarter inch material marga Cipta. That tank has been full 2 years. The seams are all still crystal clear too. I don’t want to get into this ticking match with you as obviously you’re going to win. I’ve built under a 100 tanks. But I follow this simple rule. 24” tall I use all 3/4”. 30” tall 1”. By following this simple rule I never see any bowing and Subsequent Seam fractures to follow. Nothing substantial anyway.So here we go again. Let me show you an example where simplistic rule of thumbs don't work. Here is a. 96 inch tall tank made from 3/4 inch. Zero bowing. No top. No eurobrace. I know, yeah but... Not really an aquarium etc. Just an extreme example of where simple if this then that rules don't apply. This was a research vessel for a medical device manufacturer Btw.
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OP
OP
@Cabinetman On that Marga Cipta material, that sounds a lot like something I experienced with another off-brand material that I used on a few smaller items (because for a while there, there was nothing else actually available). Astari I think. It seemed "harder" than PMACS, and using my typical 20 second soak and standard pins, 20 minutes after setting the joint you could pull it apart.
Trial and error (and consultation with @acrylics) led to using thicker pins and a minimum 60 second soak time, that dissolved enough material to get a good squish and a perfect seam. Marga sounds similar to this?
Trial and error (and consultation with @acrylics) led to using thicker pins and a minimum 60 second soak time, that dissolved enough material to get a good squish and a perfect seam. Marga sounds similar to this?
Cabinetman
Well-Known Member
Yes it does. Except my minimum is two minutes 30 seconds before I pull the pins I find that way I get a nice bit of acrylic oozing out of the seam. Honestly no matter what brand I use I allow at least two minutes before pulling the pins. And my seams always turned out absolutely flawless except for the very odd microbubble and I mean very odd..
Some of the acrylic out here is cross linked and does not bond well enough for standard solvent welds. You must use other welding adhesives. This is the case with some Chinese sheets and Reynolds Polymar.
MikeO
New Member
TaylorPilot
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It is used a lot in sign making. The problem I have found with most plastics distributors is that 99% of their acrylic sales is for sign making or structures that are not pressure vessels (hold water). The companies that do typically build industrial style tanks for holding chemicals don't use acrylic, so we really are in a niche market as far as plastics go, so they do not want to get quality cell cast brands because most clients aren't willing to pay the premium for them and they sit. I have used the 6mm acrycast to make small overflow boxes before and it works ok. I don't like the masking on it because it is very waxy and thin, so it tears really easily. Arkema branded PMAC (Same brand as Plexiglas, just different labeling)was easier to find pre-Covid. It is a little thicker, the paper backing is a lot thicker and more durable when you are throwing sheets around by yourself. After Covid started I couldn't find anything other than Acrycast for almost a year. I finally found a local regional vendor who would buy flats of Plexiglas G sheets for me. It still isn't made domestically anymore though. I do not have any experience building large displays but from my experience, acrycast wouldn't be my choice. This is the stuff that I try to use.
OP
OP
Acrycast is "harder" - that's more of a "feel" thing that you learn when working with various brands of acrylic. I've used it when nothing else is available but I don't like it. It doesn't dissolve like G or PMACS does, so I figured out that you need to use thicker pins to allow a longer soak time (like 60 seconds instead of 15) and then you have to leave the joint alone for pretty much a full day before moving it, which slows the whole process down significantly. But if you're doing a one-off sump and aren't at production level, that's fine. If I'm making dozens of ATOs in a batch, I want to bond all one side then after the last one is bonded the first one is ready to manipulate - can't do that with Acrycast, gotta leave clamps/weight on overnight to get the bond strength good enough.
Beyond that, it's fine for small stuff. It's just not as easy as PMACS and G. As @TaylorPilot said I wouldn't use it for big tanks.
Beyond that, it's fine for small stuff. It's just not as easy as PMACS and G. As @TaylorPilot said I wouldn't use it for big tanks.
OP
OP
Speaking of tanks, here's a custom 240 I built recently (internal overflow box not shown)
TaylorPilot
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It'll be fine for that...I soak it for 60 seconds as well. Especially on the darker stuff. It seems to leave a cleaner edge so you don't get that white blushing right along the seam.
cjgibson
Active Member
@Turbo's Aquatics do you have a recommendation for a bit used on a CNC router? I have a good friend with a CNC router who is willing to cut my pieces for me. But I wanted to make sure he had the correct bit. Also, any tips for setup like bit speed, depth per pass, etc etc for me to get a good starting point. I have a few small extra pieces for testing on the router. Thanks!!
OP
OP
1/4 standard bits will do fine, but use a new bit as the bits will wear and that can throw off your cut dims by just enough to make parts come out different if you use an old bit. Every CNC is different though, so it's hard to give advice. Is it a hobbyist level CNC or commercial grade with suction table? Cutting large or small parts? Movement of parts and the sheet is the issue.
Thickness of acrylic matters too. If they haven't cut acrylic before it will be trial and error. On a commercial machine with a suction table, multiple passes shouldn't be needed until you get to something like 1/2".
On thicker parts, my guy (sign company with old school beast machine) will do multiple cuts down to a few millimeters of material (not a full depth cut) slightly larger than the final dims and then on the last pass that will be the final part dims. This is so you have a nice finished one-pass edge. But that final pass, he's standing there with big wooden sticks holding the parts in place (and that's big parts).
Small parts are difficult on a CNC because the final leg of the cut, many times the parts will break loose and push. Even big parts will. So sometimes you have to leave strategically placed tabs that can be easily removed after the fact
Thickness of acrylic matters too. If they haven't cut acrylic before it will be trial and error. On a commercial machine with a suction table, multiple passes shouldn't be needed until you get to something like 1/2".
On thicker parts, my guy (sign company with old school beast machine) will do multiple cuts down to a few millimeters of material (not a full depth cut) slightly larger than the final dims and then on the last pass that will be the final part dims. This is so you have a nice finished one-pass edge. But that final pass, he's standing there with big wooden sticks holding the parts in place (and that's big parts).
Small parts are difficult on a CNC because the final leg of the cut, many times the parts will break loose and push. Even big parts will. So sometimes you have to leave strategically placed tabs that can be easily removed after the fact
OP
OP
Should be pretty straight forward then. Just food for thought, if that's rimless at those dims then 1/2" is appropriate. But if you even had a 1 or 1.5" wide perimeter eurobrace, you could drop down to 3/8".
OP
OP
You always want the bit pulling the acrylic away from the part, so yes
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