Acrylic fabrication questions? I can help!

[pepcrylic]

Doing some research on building an acrylic dropoff tank. I want to be sure my welding steps are in the correct order.
Left side welded to deepend bottom. Deepend bottom/side to dropoff panel. Rightside welded to shallow end bottom. Shallowend bottom/side to dropoff panel.
Back panel welded to Sides/bottoms, Flip it, weld front panel. ?????
The dimensions of the tank are 40'' long X 24'' front to back. The deep end will 18'' tall X 19'' long X 24'' front to back. The shallow end will be 12'' tall X 21'' long X 24'' front to back. The front and back panels will be 1'' material. The 2 side panels will be 3/4'' material, and the bottoms will be 1/2'' material.
Will I need to add a eurobrace to the top?

[Floyd R Turbo]

Actually there is a sort of magic formula...this is from James, I edited out a few extra commentary to get to just the meat & potatoes...

Start with 3" eurobrace on any tank..

24" high, use 1/2" minimum
30" high, use 3/4" minimum
36" high, use 1" minimum

...6" wide crossbrace every 24" of tank length. So a 48 x 24" will have 3" eurobrace and a 6" crossbrace.

If the same tank were 72" long - just one more crossbrace.

At 8' length, jump up one material thickness to keep deflection down.

There are times when someone's lighting scheme doesn't match the above formula. Ie., if someone wants an 8' tank but only 3 cutouts in the top. In such cases, I recommend increasing the eurobrace width to 4.5" and increasing the width of the crossbraces to 8".

1.5" radius corners

If someone doesn't want the crossbrace - they simply have to make the material thicker, and/or increase the width of eurobrace to maintain rigidity.

I think with your extra thickness on walls and 6" euro you might be fine, as long as your cutout radius was good or larger.

James would be the best to answer this though for confirmation

[pepcrylic]

Originally Posted by Floyd R Turbo

Actually there is a sort of magic formula...this is from James, I edited out a few extra commentary to get to just the meat & potatoes...



I think with your extra thickness on walls and 6" euro you might be fine, as long as your cutout radius was good or larger.

James would be the best to answer this though for confirmation

TY Floyd. With the 1'' material front and bacl, and the 3/4'' material on the sides,and the deepest part of the tank only being 18'' . I think the 6' euro is way over-kill. I am not so much worried about the size of the euro, or even if it is needed as I am courious about the ordered in which the dropoff tank is welded together. Do you have any insight on that process?

[Floyd R Turbo]

The rimless equation is different. I don't know that one off the top of my head.

As for the dropoff tank assembly order, I think that was covered somewhere in this mega thread, again, I don't know it or where the pertinent posts are...

[pepcrylic]

Floyd, I found some info on the dropoff Page 193, Post #4805.
Not sure I understand how the steps are executed. Could maybe you have a look and maybe able to elaborate??

[Floyd R Turbo]

Link?

[pepcrylic]

http://www.reefcentral.com/forums/sh...56956&page=193

[Floyd R Turbo]

Originally Posted by pepcrylic

http://www.reefcentral.com/forums/sh...56956&page=193

For me that's page 97 as I go by 50 posts/page here.

Direct link to post http://www.reefcentral.com/forums/sh...postcount=4803

[Terry6000]

Not to side track the drop off tank conversation but from the piece about euro thickness
Can you continue the euro thicknesses down
18 inches high would be 3/8
12 inches high would be 1/4

My all in one tank is 16 inches high with a water height of about 14.5 inches and the main section of the tank is 82 inches long would need Between 1/4 and 3/8 thick 3 inch around euro with 6 inch cross braces.
My q lies If I use 1/2 thick can I go down to a 2 inch wide brace with the 3 6 inch cross braces?

[Floyd R Turbo]

The 3" perimeter + 6" cross I believe assumes you are using 1 size thinner for the top/bottom, but I'm not 100% sure on that. When in doubt, make them the same thickness (matters more for a DT vs sump w/structurally constructed baffles)

IMO 3/8" thick is the thinnest I go for the walls, even on a sump > 12" tall, but for a sump, 1/4" top & bottom is ok.

For a 82" long tank, definitely 3/8" walls, maybe even 1/2" due to the span

But the euro, IMO, is somewhat dependent on the height as it is there in part to reduce bowing, so on a shorter height tank, this is less so you can get away with less - in your case, 1/4" is what I would personally use for the euro, at the standard 3/6. But you are correct, if you bump up to a 3/8" euro you can probably reduce the perimeter, if you beef it up to 1/2" and 1/2" walls, your euro can likely be even narrower, but I'm guessing that there is a point of diminishing returns. The 2" perimeter and 3x 6" crossbraces would probably be OK with a 1/2" euro but I would pay extra attention to the corners of the cutout - increase the radius to 2" (4" diameter) or more, make sure the transitions are extra smooth, and roundover the edge on both sides with a 1/8" roundover as well. Then sand out any bumps or anything to make sure that inner edge of the cutouts doesn't have any stress points.

The issue with most tank failures that I see is usually cracking out at the corners of the euro, because this is where all the stress is focused. #1 - Wide sweeps spread that stress out, #2 stress focuses on any sharp corner

^ #2 includes any sharp exterior corner anywhere on the tank, so you should, at a minimum, knock down any sharp exterior corner of the tank with a razor blade at a 45 degree angle (not just so you don't cut your hands on it)

[Terry6000]

Thank Floyd. The inter radiuses make a lot of sense but i never would have thought the exterior edges.
Now for the opposite could I stay with the 3 inch edge and do one center brace 10-12inches wide with wide brace at the ends? I can see my self trying to get a nice long piece of driftwood in this tank one day.

Also is there any books, website or equations you can point me to? Or do just have all the answers from life experience?

[Mrs. Music]

The acrylic I have recently purchased from Lowes is more brittle after heat bending it, as compared to previous experiences. Anybody know why this could be? or perhaps I should be asking what should I buy for small projects that require heating and bending acrylic?

[Floyd R Turbo]

Might I ask: did it have a brand-name on the label, or a type? (cell cast, coninuous cast, extruded, etc)

Also, what are you using it for? i.e. what are you building?

[Mrs. Music]

Originally Posted by Floyd R Turbo

Might I ask: did it have a brand-name on the label, or a type? (cell cast, coninuous cast, extruded, etc)

Also, what are you using it for? i.e. what are you building?

Thank you for helping Floyd. I build odds and ends for my aquarium such as algae clips. the label just says acrylic...

[Matthias7]

I am planning on building a frag tank in the near future. The dimensions are 70in x 12in x 18in(wide). Is 3/8in acrylic good for those dimensions. I will have a eurobraced top as well.

[Zephrant]

Are you going to do any cross braces? At 12" deep, 3/8" is plenty but you still need some braces. Two 4" cross braces would do wonders for long term stability, along with 3" eurobracing.

[Matthias7]

Yes was planning a eurobrace, I would prefer to do just 3 crossbraces if that is safe?

[Zephrant]

Three cross braces with euro would be fine. I'd be worried about the sides bowing too much if you only did cross braces.

[JRunyon21]

I'm look to put together a large acrylic aquarium. The dimensions would be 96"L x 32"W x 23.5"H. I'm not new to aquariums but I am new to building one. I'm a fairly handy guy with a really nice shop downstairs which includes an 8.5' x 3' shop table for assembly. I have read most of this article including the original and this is my plan.

3/4(.708)" Polycast cell cast acrylic 72" x 96"
3/4(.708)" Polycast cell cast acrylic 48" x 96"

Bottom - 96" x 32"
Front/Back - 96"x23.5"
Sides - 30.584" x 23.5"
Front top brace - 4" x 96"
Back top brace - 2" x 96"
Side/cross top braces (6) - 5" x 26"
All in 3/4"
I will also use the leftover 3/4" x 96" x 5" pieces (2) to build a Calfo overflow system that should also act as a brace for the back.
I would use the remaining scrap to test weld as much as possible.

Should this amount of bracing, including the Calfo Overflow, be enough?

Also, I plan to use the pin method with .0125" guitar string or 26 gauge pins and Weldon 4. Each piece will be prepped with a router and laminate bit. Attach sides to front. Attach back to sides. Attach top braces. Attach bottom.

As added comfort I was thinking of using the tilt and pour method with Weldon 40 to put a 3/8" "bead" in each corner to add additional conservatism to the build.

What are the community's thoughts on my

1. Acrylic Size?
2. Bracing?
3. Methodology?
4. Extra tilt and pour?

Thanks in advance for this amazing article and your responses.

[Floyd R Turbo]

Polycast is imperial thickness, so 3/4" = 0.750". It's Plexiglas-G that is metric, or 3/4" = 0.708" so take that into account.

If your OD requirement is 96 x 32 x 23.5 then your ends are going to be 2 * thickness smaller, so if 0.750" thick, ends will be 30.5 x 22 pieces, f/b will be 96.25 x 22, top/bot 96.25 x 32.25.

The added 0.25 is for allowing the fillet to form and to allow for flush trimming. The ends are actual dimensions since they are bonded on all 4 sides. The 0.25 can be 3/8", 1/2", or more, as long as you have enough to work with to allow for the fillet.

Squaring of the ends is important. These 2 pieces really need to be square, but more importantly, they need to be the same. It's a bit tough with 3/4" thick to double-stick tape those together and run them through the router to make them identical, but at worst they should have one corner squared off then they can be separated as long as each pass is done to both pieces back-to-back with the same settings.

Then for the front/back, you will pass these through such that both are the same height, and the same height as that same dim on the ends. So your final pass would be all 4 pieces with the same fence setting on the router. Tricky when you have 96" long pieces I imagine, maybe James/Acrylics can give you advice on that, I haven't made a tank that large.

top/bottom can be rough cut, you're going to trim off all 4 edges anyways.

For pins, get a hold of some stainless steel wire that dentists use for braces. Tough stuff, can handle the weight of the panels.

For solvent, I would try to DIY some. WO #4 isn't really that great, MC with 5% glacial AA and you're good for sure.

Should not need WO40 beads. James has stated in this thread that he solvent welds up to 2" thick panels, and then there's the whole WO40 vs solvent weld strength debate (short version: correctly done solvent welds win)

Question: laminate bit?

[Zephrant]

Great advice, but I'd suggest that this is not the place to learn how to mix acrylic solvent. Buy a pint or two of #4, and use it.

A couple of rollers and some saw horses can really help with 96" panels. Get setup with an infeed and an outfeed table to the router, and use fingers to keep the panel against the fence.

[lapin]

If you are not very precise with your machining WO40 can be used as it will fill in some unevenness. (is that a word?) I use a gig to hold panels in place and right angle clamps to be sure its perfect 90 degree square. A little angle helps with flow into the joint. Fun stuff.

[Floyd R Turbo]

Originally Posted by Zephrant

Great advice, but I'd suggest that this is not the place to learn how to mix acrylic solvent. Buy a pint or two of #4, and use it

There is no mixing. You can use straight Methylene Chloride, right out of the bottle.

Get a very small amount of Glacial Acetic Acid and mix in 5% of that on volume and that causes the solvent to flow better when applying it.

That's literally as complicated as it gets. That 5% is ballpark. As long as it's less than 10% you're good. Even if it's only 2%, that works. It's really easy.

Weld-on #4 is fine for sumps, frag tanks, small projects, etc. But if I were investing 1000s into a display tank I would spend $50-$150 on the quality ingredients. Call it an investment

[JRunyon21]

Thank you so much for advice. I will definitely look into the MC.

As far as a laminate bit...I thought I read somewhere that a laminate bit is a straight bit with a bearing on the end but I may have made it up. I intend to use a straight bit with a bearing on the end to shave off excess bottom/top material post construction as well a straight bit to joint all the joints. Any suggestions on brands?

Also, what brands of Acrylic should I be looking for? Chemcast? Polycast? Plexi-Glass?

Thanks in advance.

[Floyd R Turbo]

You posted "Polycast" above, so I thought that's what you were going to use. You mentioned having read this thread (article?) but this thread is several splits long and there is a ton of info, it took me weeks to get through it all in detail....so I'm guessing you didn't read it all?

Polycast is $$$ but it is good stuff. Plexiglas-G is the alternative. There pretty much is no other choice anymore. Acrylite used to be an option but after they've had some changes, and some reputable builders have ended up with acrylic that won't weld, that one had been dropped off the list. Synergy Reef won't even make sumps out of it anymore.

The laminate bit is really not useful because that is a straight fluted small diameter bit. The spiral upcut flush cutter is for trimming, and with 3/4" thick material, you will want a 1/2" diameter one.

For edge prep, you want a double-fluted straight cutter with a good diameter to it.