Acrylic fabrication questions? I can help!

[troylee]

Apparently it was left sitting in the sun with vinegar in it for a couple weeks, years ago. Since it will be a sump it is not critical it look perfect. I would like to clean it up some if possible. It have been in use by another RC member who added the baffles until recently.

both the sun and vinegar will do a number on acrylic after awhile..... im pretty sure the expansion and contraction from such tempeture changes did most of that....not much you can do, but try sanding and polishing... maybe just try the polish first on a big buffer and see if your gonna be happy with it before you commit.... it's really alot of work that is not gonna make a huge difference... "sorry"

 

[troylee]

Allright here goes, im building a 700+ gallon tank, its 96x48x35 tall. Material is acrylite gp cell cast 1 1/4" acrylic. I got the material on a killer deal, less than 25% of cost, the bottom and top are 48x96" sheets with saw cut edges that will trimmed off with router after tank is built(they are oversized by about 1/4"). The front back and sides i had a plastic shop cut them to size and route the edges for a perfect fit. I have since sanded the edges with 180 grit sandpaper and a da sander holding it nice and sguare.

here are my questions

1- where the sides sit on top of the bottom panel do i need to sand that area before boding? in 1.25" from the edge around the parameter? along ith the other panels that will be bonded?
no you dont need to sand or scuff..... but clean very well with denautre alcohol right before gluing....

2-i will be using weld on #40 using a larger hypo needle to apply, its a large one and holds 100cc/ml , ive allready tried a test to make sure the #40 will flo through it, works like a charm.
gluing such big panels is a real pain and the prep work is painstakingly long, masking etc... i would use solvent's or weldon 42 it comes ready to go out the gun.... mixing 40 to get it right depends on number of factors and if your mix kicks before you finish laying a bead you got more problems....."waiting for the bubbles to clear takes awhile"

3-i will not be annealing the acrylic as i dont have a $100,000 oven to do this, do you see a problem in this?
no problem there....
4- i am building this in my garage and have 2 small chain hoists to lower the panels while bonding, whats the best procedure for this? Should i apply the #40 on one surface to be bonded and then place a couple pins to allow a gap so the panels can soak and then pull the pins and allow the access to squeeze out? Or should i place pins, set panel and try a capilary action with the #40 using thicker pins like .03"-.06"? and then allow to soak and then pull pins ??? ive never used #40 before
no pins...."way different than solvents" you can use very very thin acrylic shims and leave them in to create the gap your looking for 1mm or so....you dont want the panels to squeeze all the glue out of the joint...1.25" is heavy and will....

5-any tips on routing the edges of the panels? i have a 3/8"x2" router bit for acrylic with nylon bearings, one bearing is 3/8" and the other is 7/16" so i can route it in 2 passes rather than trying to take off alot of material in 1 pass, router is a 3/4 hp model(not a cheapie) this depends on how much material you need to take off.... i would suggest a spiral upcut 1/2" shank for this cuts nicer than standard 2 and 3 flute flushcuts....it also puts alot less stress on the router....

ive built a few acrylic tanks and sumps before so im not that new to acrylic, just never messed with anything thicker than 1/2" and never used anything other than weldon #4 using capilary and #16 for the occasional flaw.

Ive searched all over the net trying to find info on this and there isnt much.........



__________________

 

[noobtothereef]

do they sell acylic thats 1mm? or should i just try to cut some? i dont think i can cut a piece of acrylic for a shim 1mm thick but that is a great idea, if i used pins the weight of the panel would just push the pins into the acrylic.

heres how im going to do it

1 mask panel edges near glueing area
2-clean all areas with denatured alcohol(have used acetone in the past)
3-glue in 1mm shims of acrylic onto one panel
4-apply #42 to the panel
5-lower panel onto other panel that the #42 was applied to( im going to have to be fast doing this on an 8' long panel, will probably need another person to help me do this so the solvent does not begin to dry)
6-after panel has been placed i will have to wait for about 2 hours before placing the next panel, on weldon's site it says can be worked with in 2 hours, i might even wait longer than that

now more questions

should i glue the front sides and back together first, then place on top of the bottom sheet and glue it all at once? and then flip it and do the entire top at once? Its going to be hard to apply 24' of weldon without it starting to dry, but i think thats my only option, my garage is air conditioned and may put a dehumidifier in it while i do this to slow the drying process.

next question, should i apply 1 large bead of weldon in the center of where the panel will be placed and let it smash the weldon into the entire joint? i would think doing this would allow the air to escape from both sides of the weldon rather than a few smaller beads and trapping air between the beads.

Also you mentioned the spiral upcut, is there spiral upcut bits that can be used for plunge cuts? I will be running an external overflow box and need slots in the top back of the tank for water to pass through, i may just have this done at the plastic shop on there cnc table.

Also does weldon 42 bubble like the 16 if left in the inside corner? i used weldon 16 to repair a seam on an old tank and after it tried it was just bubbles. I also noticed how expensive weldon 42 is, how many tubes would i need for this? They are only 230ml and the dispenser for it is $250

 

[mudskipper1]

Alright, I am planning a small Acrylic tank, less than 10 gallons. I was thinking about doing a tank with non-90 degree angles to make a trapezoid. How difficult would this be? Unfortunately, I purchased acrylic from "craftics" before I found this thread and read about how the specific manufacturer is very important. So i just asked whether the acrylic is cast, continuous cast or extruded, no answer yet. The acrylic is 3/16".

How feasible is a trapezoid tank for an inexperienced acrylic worker? If at all, what, if any bracing would be necessary?

Would extruded acrylic sheet be okay for this small of a tank?

Any help would be greatly appreciated!

 

[laverda]

both the sun and vinegar will do a number on acrylic after awhile..... im pretty sure the expansion and contraction from such tempeture changes did most of that....not much you can do, but try sanding and polishing... maybe just try the polish first on a big buffer and see if your gonna be happy with it before you commit.... it's really alot of work that is not gonna make a huge difference... "sorry"

troylee
Thanks that is kind of what I was figuring. At least I know now.

 

[noobtothereef]

Alright, I am planning a small Acrylic tank, less than 10 gallons. I was thinking about doing a tank with non-90 degree angles to make a trapezoid. How difficult would this be? Unfortunately, I purchased acrylic from "craftics" before I found this thread and read about how the specific manufacturer is very important. So i just asked whether the acrylic is cast, continuous cast or extruded, no answer yet. The acrylic is 3/16".

How feasible is a trapezoid tank for an inexperienced acrylic worker? If at all, what, if any bracing would be necessary?

Would extruded acrylic sheet be okay for this small of a tank?

Any help would be greatly appreciated!

if it was cheap im guessing its probably extruded, especially if it has the blue/clear plastic coating. It wouldnt be that hard if you have a table saw to cut the angles on the edges of the panels, for the top and bottom just leave it square until you bond the sides to it and router it off

 

[Acrylics]

Is weldon 40 the same as acrifix 0190?

Pretty much

Thanks James!!

Does the novus need to cleaned in all areas with alcohol before filling the tank with saltwater?

no, it doesn't. Once a tank is complete, I try to keep alcohols away.

I have been reading through this thread, and is seems as if I am in the right place. I have recently purchased and older ******* acrylic tank. this is a 96x18wx24h 180gallon. I could not refuse the price, all things asided, I think the stand was worth it.

This tank is currently holding water in my basement, there is a cut-out that has been made in the euro brace for a HOB filter, there is quite a bit of crazing too.

Is it worth fixing the top and polishing the tank?

IMO, no. You'll probably make it worse by trying to "fix" crazing, which simply cannot be done. Crazing is acrylic's way of relieving stress. If there is crazing, the material has been pushed beyond it's capabilities or has been stressed in other ways - solvents, flame polishing, that sort thing.

The current deflection of the tank being filled is approximately 1/2" to 3/4", the manufacturer says that is within tolerance.

Ugh There should be nothing near that amount of deflection for a tank that size. I don't know who the mfr is, but they suck if that's within tolerance.

HTH,
James

 

[Acrylics]

do they sell acylic thats 1mm? or should i just try to cut some? i dont think i can cut a piece of acrylic for a shim 1mm thick but that is a great idea, if i used pins the weight of the panel would just push the pins into the acrylic.

Yes, they sell 1mm acrylic, you should be able to find it as thin as .020" (.5mm) pretty easily.

heres how im going to do it

1 mask panel edges near glueing area
2-clean all areas with denatured alcohol(have used acetone in the past)
3-glue in 1mm shims of acrylic onto one panel
4-apply #42 to the panel
5-lower panel onto other panel that the #42 was applied to( im going to have to be fast doing this on an 8' long panel, will probably need another person to help me do this so the solvent does not begin to dry)
6-after panel has been placed i will have to wait for about 2 hours before placing the next panel, on weldon's site it says can be worked with in 2 hours, i might even wait longer than that
Personally, I think you're going to have problems. This is not the process for doing it, at least not in any shop I've ever seen

now more questions

should i glue the front sides and back together first, then place on top of the bottom sheet and glue it all at once? and then flip it and do the entire top at once? Its going to be hard to apply 24' of weldon without it starting to dry, but i think thats my only option, my garage is air conditioned and may put a dehumidifier in it while i do this to slow the drying process.This is the way it's done. Normally we route an angle on acrylic that is to be "cast" (glued with 40/42) so that the one side of the joint has a ~1/8" gap and the other has 1/16" gap and let capillary action (surface tension) suck the cement in. Most shops will use solvents for the top and bottom for ease of mfr

next question, should i apply 1 large bead of weldon in the center of where the panel will be placed and let it smash the weldon into the entire joint? i would think doing this would allow the air to escape from both sides of the weldon rather than a few smaller beads and trapping air between the beads.See above

Also you mentioned the spiral upcut, is there spiral upcut bits that can be used for plunge cuts? I will be running an external overflow box and need slots in the top back of the tank for water to pass through, i may just have this done at the plastic shop on there cnc table.Yes there are, but not with bearings needed for flush-cutting

Also does weldon 42 bubble like the 16 if left in the inside corner? i used weldon 16 to repair a seam on an old tank and after it tried it was just bubbles. I also noticed how expensive weldon 42 is, how many tubes would i need for this? They are only 230ml and the dispenser for it is $250
No, it doesn't bubble like 16, it is entirely different and the number of cartridges you need will be determined by the gap you leave. You can do the math to figure volume and (IMO) double it (at least) to get the number of tubes you'll need. Do not "push" the cartridge to the end, the end of each cartridge is chock full of bubbles

I'm really not trying to sound "snotty" but from the sounds of it, IMO you're in over your head on this at this point. Do a lot more practicing in thicker materials before attempting this. Once you start laying 40/42, there is no turning back. Most folks can be taught to build something using solvents in a couple of hours, casting joints on something this size is a whole different ball game and IMO really requires a ton of practice and perhaps some lessons to get it "right"...but JMO

James

 

[noobtothereef]

I'm really not trying to sound "snotty" but from the sounds of it, IMO you're in over your head on this at this point. Do a lot more practicing in thicker materials before attempting this. Once you start laying 40/42, there is no turning back. Most folks can be taught to build something using solvents in a couple of hours, casting joints on something this size is a whole different ball game and IMO really requires a ton of practice and perhaps some lessons to get it "right"...but JMO

James

So routing the edge at an angle, when the panel is placed at a 1/16" gap and an 1/8" gap, fill the joint and then let is cure like that? No need to lower the panel down so its a 0" and 1/16" gap after the 42 has been laid? I have quite a bit of scrap from the opeing in the top panels that were cut out so i can practice this till im blue in the face, i didnt spend $4k on the material for this tank, less than $1k(left over materiald from a job at my brothers cnc machine shop) i was going to have the plastic shop build it but, at $3500 for labor, i will buy everything i need tools etc. and do it myself. Im taking my time doing this, and im on here asking you guys how to do this so i do it right the first time, this is the thread called "acrylic fabrication questions? I can help!" right?

Im not too concerned with a few bubbles in the joint either, this is an in-wall tank anyway and wont see any seams, the only edges that are polished are the openings in the top

 

[Acrylics]

So routing the edge at an angle, when the panel is placed at a 1/16" gap and an 1/8" gap, fill the joint and then let is cure like that?

Yep, 40/42 is not a solvent that fuses the 2 pieces together. It is an actual acrylic resin that fills the void and sticks to the other pieces. You do want to "overfill" it though, it will contract some, just not as much as 16

No need to lower the panel down so its a 0" and 1/16" gap after the 42 has been laid?

no need IME

(snip)...this is the thread called "acrylic fabrication questions? I can help!" right?

Yeah...and?

Im not too concerned with a few bubbles in the joint either, this is an in-wall tank anyway and wont see any seams, the only edges that are polished are the openings in the top

Then out of curiosity, what do you have against solvent bonding?

James

 

[noobtothereef]

Yep, 40/42 is not a solvent that fuses the 2 pieces together. It is an actual acrylic resin that fills the void and sticks to the other pieces. You do want to "overfill" it though, it will contract some, just not as much as 16

no need IME

Yeah...and?

Then out of curiosity, what do you have against solvent bonding?

James

i have nothing against solvent bonding, ive had good luck with it in my previous builds, i have read quite a few large builds and most use 40/42, maybe because they are shooting for perfect joints on exposed corners. I just want it to be as structurally sound as possible.

 

[Acrylics]

Solvent bonded joints are comparable to unannealed 40/42 joints, so ya know.
And you'll never see 2500psi in this tank. Do what you feel is best, but IMO - stick with what you're most comfortable with. 1.25" material and a good solvent bond will stand up to anything you'll see in your tank...

 

[troylee]

i could'nt explain it any better than james just did..... casting them joints is a pita and very time consuming.....solvents would be better for you imho because you have exp. with them...practice on your scraps with both and see what you come up with.... i could almost bet when it's showtime you will be using the solvents.....

 

[Poriferan]

How long of a span can 3/4" acrylic be supported by 3/4"plywood?

For example, My tank is 8' long and 30" tall. It sits on the plywood and has 4x4 supports under the plywood at the corners and the middle along the edges. There is 1" foam between the plywood and the tank but the 3'+ sections along the front would be unsupported. Is this oK or would adding a 2x4 in the center of the span be necessary? I have always seen a frame with 2x6 wood used to support tanks. I wonder because I have seen large 3'x3' cube tanks with no support in the center, just at the edges.

Any advice would be most helpful.

 

[noobtothereef]

i could'nt explain it any better than james just did..... casting them joints is a pita and very time consuming.....solvents would be better for you imho because you have exp. with them...practice on your scraps with both and see what you come up with.... i could almost bet when it's showtime you will be using the solvents.....

im thiing that might be a better idea , what does everybody recomend for surface prep for the router cut edges? I have sanded them down with 180 and then 320, will this be sufficient? My last build i only 80'd them and had a few bubbles in the 80 scratches. Also what would somebody recomend for a strong pin for spacing the panels apart for using solvent? My last build was a 120(48x24x24) and when pulling the pins i broke a pin and just left it in there, for this buld i will need something stronger, i was thinking about using some hardened sewing machine needles that i have, i took one and clamped it in the vice and it is strong as ****, i will have to measure the thickness, my guess is that they are .015"-.02", im thinking they may be a little too thick, for solvent bonding dont we shoot for around .01" like a breadtie? With this much weight a breadtie will break like they did on my 120

 

[j5hughes]

I will be getting some acrylic CNCed soon @ work to make a reactor. I have extruded tube & cast for the base plate & flanges. What would be my best option for gluing?

 

[noobtothereef]

i just put together 6 reactors tonight lol, i made my bottom and top plates with 1/2" and cnc'd the holes in the middle 8"(od of the tubes) and slid the tubes into the plate and used weldon #4 utilizing capilary action, i was going to place the tube ontop of the plate and bond it like that but i couldnt fit the 8" tube in the lathe to true the ends perfectly flat, i made them so both the top and bottom caps could be removed, had to make 4 plates. If you have lathes at work just throw your tube in a lathe and square the ends on them, most saw cut tubes are way off for solvent bonding, are you going to cnc an "o" ring groove in the plate for the seal on the cap? use an 1/8" ball mill .08" deep and use an 1/8" o ring, napa sells the o-rings for about $1, just be sure to keep the o ring dimension in 1/4" increments like 4.75,5,5.25" etc... thats the sizes they sell.

Sorry for the long post, really interested in your reactor build to see how you do it. Post some pics up of the build

 

[j5hughes]

i just put together 6 reactors tonight lol, i made my bottom and top plates with 1/2" and cnc'd the holes in the middle 8"(od of the tubes) and slid the tubes into the plate and used weldon #4 utilizing capilary action, i was going to place the tube ontop of the plate and bond it like that but i couldnt fit the 8" tube in the lathe to true the ends perfectly flat, i made them so both the top and bottom caps could be removed, had to make 4 plates. If you have lathes at work just throw your tube in a lathe and square the ends on them, most saw cut tubes are way off for solvent bonding, are you going to cnc an "o" ring groove in the plate for the seal on the cap? use an 1/8" ball mill .08" deep and use an 1/8" o ring, napa sells the o-rings for about $1, just be sure to keep the o ring dimension in 1/4" increments like 4.75,5,5.25" etc... thats the sizes they sell.

Sorry for the long post, really interested in your reactor build to see how you do it. Post some pics up of the build

Thanks for the info especially the O ring info that has been one thing I was not to sure on. I wasn't sure if I could get a ball point bit for the router. I got my O rings from geo should I just make the o.d. for the groove the same as the O ring size & then do an 1/8" inline on that for the i.d? or do you need to add or subtract for stretch of the O ring?

Also if I use weldon 4 will I need to polish the edges? They are factory & it seems like a quick sanding with a block and some fine grit would be sufficient. As far as I can tell they seem to sit square, but I never really tried to check that. I have 1" clear for the base what's a good depth for the tube to recess into?

Thanks again

 

[Acrylics]

How long of a span can 3/4" acrylic be supported by 3/4"plywood?

For example, My tank is 8' long and 30" tall. It sits on the plywood and has 4x4 supports under the plywood at the corners and the middle along the edges. There is 1" foam between the plywood and the tank but the 3'+ sections along the front would be unsupported. Is this oK or would adding a 2x4 in the center of the span be necessary? I have always seen a frame with 2x6 wood used to support tanks. I wonder because I have seen large 3'x3' cube tanks with no support in the center, just at the edges.

Any advice would be most helpful.

It depends on the beams under the tank and how much deflection you see. IMO, water test it slowly, over a period of days, and check for gaps. If you see gaps, you'll know what to do
And BTW, foam is not necessary under acrylic tanks IME, unless there's nail/screw heads protruding from the deck.

James

 

[Acrylics]

im thiing that might be a better idea , what does everybody recomend for surface prep for the router cut edges? I have sanded them down with 180 and then 320, will this be sufficient? My last build i only 80'd them and had a few bubbles in the 80 scratches. Also what would somebody recomend for a strong pin for spacing the panels apart for using solvent? My last build was a 120(48x24x24) and when pulling the pins i broke a pin and just left it in there, for this buld i will need something stronger, i was thinking about using some hardened sewing machine needles that i have, i took one and clamped it in the vice and it is strong as ****, i will have to measure the thickness, my guess is that they are .015"-.02", im thinking they may be a little too thick, for solvent bonding dont we shoot for around .01" like a breadtie? With this much weight a breadtie will break like they did on my 120

If the edges have been routed smooth, no other prep is necessary. I don't do anything other than route the edges smooth.

As for wires, I simply use twist-ties (.014") for up to 2.5" acrylic. When the tank weighs 3-4000lbs, you want to use a bunch of them but in your case - every 6" or so should be fine

IMO glue on foam so you can press down a little on the bottom sheet to remove the wires.

James