I would be more worried about using a scraper on 2 1/2'' material to prep an edge than I would be about the small pits.
It wont take much scrapping to ruin a FLAT edge.
Acrylic fabrication questions? I can help!
- Thread starter JohnL
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I would be more worried about using a scraper on 2 1/2'' material to prep an edge than I would be about the small pits.
It wont take much scrapping to ruin a FLAT edge.
Phixer
New member
Thanks you guys, really appreciate the info.
Took a closer look at the bonding surfaces today and they appear to be pretty smooth unlike the edges I described earlier. So Im hoping they will be alright. The edges with the small pits are outside edges and wont get bonded.
Peppie, unlike solvent cementing, when bonding with the 2 part stuff edge flatness isn't as big an issue as long as the edge is smooth because the joint is cast within the cement (if that makes sense). In other words the entire joint remains encased in cement. I wasnt sure if it would fill in the tiny pits though and provide uniform strength across the face of the joint.
The mechanical design of the joint is very important when bonding this way so I beveled the edges to be bonded 5 degrees across the face.
The reason I was concerned about the pitting was because crazing can propagate from these pits.
When solvent cementing, flatness is essential and bonding a smooth yet uneven surface would result in bubbles and dry spots. I hear ya. Personally Id never use solvent for anything over 1" thick just because it's harder to achieve uniform penetration throughout the thickness of the material. It can be done but I just like the 2 part stuff with beveled edges much better.
Loaded the panels today, very heavy.
Took a closer look at the bonding surfaces today and they appear to be pretty smooth unlike the edges I described earlier. So Im hoping they will be alright. The edges with the small pits are outside edges and wont get bonded.
Peppie, unlike solvent cementing, when bonding with the 2 part stuff edge flatness isn't as big an issue as long as the edge is smooth because the joint is cast within the cement (if that makes sense). In other words the entire joint remains encased in cement. I wasnt sure if it would fill in the tiny pits though and provide uniform strength across the face of the joint.
The mechanical design of the joint is very important when bonding this way so I beveled the edges to be bonded 5 degrees across the face.
The reason I was concerned about the pitting was because crazing can propagate from these pits.
When solvent cementing, flatness is essential and bonding a smooth yet uneven surface would result in bubbles and dry spots. I hear ya. Personally Id never use solvent for anything over 1" thick just because it's harder to achieve uniform penetration throughout the thickness of the material. It can be done but I just like the 2 part stuff with beveled edges much better.
Loaded the panels today, very heavy.
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brian cummings
New member
I got some better bits off amazon and at a local plastics supplier. That made a world of difference. The o-flute straight cutter gave me beautiful edges. For the bulkhead holes, I followed Floyd Turbo's advice, and drilled them undersize with a hole saw, then using a template routed them out to spec- smooooth.
Phixer
New member
Floyd, whats your take for bonding these two 4x8 sheets end to end?
I had a 5 degree bevel milled on each 4ft mating end that I plan on casting with cement. Like a V when mated together. The top and bottom edge of each 8ft panel also have a 5 degree outside bevel that I plan on casting to the top and bottom panels when assembled.
Considered an overlapping 45 degree butt joint (the extra surface area would have been nice) but because of this increased area and chance for more bubbles and a greater margin for error when making this cut (would have required a longer bit too) I decided to go with the V joint.
From what I've studied and observed on public tanks they almost look like two flat 90 degree edges butted up and glued together.
I had a 5 degree bevel milled on each 4ft mating end that I plan on casting with cement. Like a V when mated together. The top and bottom edge of each 8ft panel also have a 5 degree outside bevel that I plan on casting to the top and bottom panels when assembled.
Considered an overlapping 45 degree butt joint (the extra surface area would have been nice) but because of this increased area and chance for more bubbles and a greater margin for error when making this cut (would have required a longer bit too) I decided to go with the V joint.
From what I've studied and observed on public tanks they almost look like two flat 90 degree edges butted up and glued together.
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Floyd R Turbo
Either busy or sleeping
You got me. Never worked with large material or cast joints myself
Floyd R Turbo
Either busy or sleeping
for a rimless tank that long, I think you're going to want thicker material. Probably upwards of 2". Otherwise it's gonna bow like a motha which will really stress the vertical seams. At least that is what makes sense to me. James would be better to answer that one but no idea where he's at...
Phixer
New member
Thats right, the same techniques used for solvent cementing smaller tanks dont work with thicker acrylic used to build big tanks. Mainly because the big tanks use cast joints of WO 40/42 or PS30 rather than solvent.
I've found granite slab lifters to work pretty well in supporting the panels allowing a gap for the cement to fill in. Abaco makes several that clamp the material in rubber jaws. Ive tested them on 2.250 material supported by gantry cranes and they work pretty well.
I had to forget everything I learned about edge prep and solvent cementing when I started building over 1" thick using the 2 part stuff.
It's a totally different process casting these joints and the mechanical design of the joint is much more important. You actually want something for the cement to 'bite into" and the same perfectly smooth edge used for solvent cementing wouldnt fair so well with a joint cast using polymerizable cement.
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Floyd R Turbo
Either busy or sleeping
LOL here's a good one, I was on the phone with one of the Cyro guys (who had been around for a long time) and he said he would never build an aquarium with solvent welded joints, he would go with a 2-part instead. When I asked him why he said that in their testing the joint broke on the solvent weld whereas the material broke on the 2-part weld. Then I asked him how long he let the joint cure and I think I stumped him. When I told him that you had to let joints with thicker material cure longer (for 1.5", it would be a month) before letting it see water, I think I could have seen the blank look on his face through the phone.
He them proceeded to tell me that he doesn't know a tank manufacturer who builds big tanks using solvent.
Just goes to show, just because you're an "expert" in your field doesn't mean you know a thing!
He them proceeded to tell me that he doesn't know a tank manufacturer who builds big tanks using solvent.
Just goes to show, just because you're an "expert" in your field doesn't mean you know a thing!
Phixer
New member
LOL, that's pretty funny Floyd. You should have messed with his head and told him a blow torch will speed up the process. Most of the engineers I've spoke with lack the practical experience when it comes to building acrylic aquariums, there are a small handful of fabricators out there with experience building the big tanks but most wont devulge how to do it, personal experience seems to be the best teacher.
dattack have you ever tried to bond material over 1" with solvent? I've never been able to get uniform coverage no matter how good the surface was prepped or was able to produce a bond as good as the 2 part stuff with solvent on anything 1" or larger. If so how do you get the same coverage with solvent after the pins are yanked, I always got bubbles.
I dont lend much credibility to most of the acrylic aquarium MFGs out there today and would personally never buy from them. Im sure it happens but I've never seen a clear joint of this thickness with solvent.
dattack have you ever tried to bond material over 1" with solvent? I've never been able to get uniform coverage no matter how good the surface was prepped or was able to produce a bond as good as the 2 part stuff with solvent on anything 1" or larger. If so how do you get the same coverage with solvent after the pins are yanked, I always got bubbles.
I dont lend much credibility to most of the acrylic aquarium MFGs out there today and would personally never buy from them. Im sure it happens but I've never seen a clear joint of this thickness with solvent.
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dattack
Active member
Phixer,
Most important thing is the name brand of acrylic and the acrylic solvent. I think I have tried all the commercial brand name solvents and they all leave more bubbles tI considered quality. I have gone to big name manufacturer warehouses that build tanks and they all have their glue custom made. I used James ratio of solvent and it is the best for me. I made a few rimless frag tanks up to 1.25 and most are bubble free using pin methods.
Most important thing is the name brand of acrylic and the acrylic solvent. I think I have tried all the commercial brand name solvents and they all leave more bubbles tI considered quality. I have gone to big name manufacturer warehouses that build tanks and they all have their glue custom made. I used James ratio of solvent and it is the best for me. I made a few rimless frag tanks up to 1.25 and most are bubble free using pin methods.
Floyd R Turbo
Either busy or sleeping
That custom mixture is 80% Methylene Chloride, 15% Elthylene Dichloride, 5% Glacial Acetic. I use MC with 5-7% AA since EDC is like $140/gallon and really nasty.
EDC and AA both slow down the reaction time and "thicken" the solvent. Straight MC runs very fast and is hard to control.
For larger joints, James told me he uses the #16 needle and 2oz bottle from Craftics, and I've got one of these but lemme tell you I'm scared to use it. He told me that he can get around a 12' or longer joint before the solvent sets, by himself. The other nice thing I learned about EDC is that it makes solvent useable in more humid conditions, i.e. the solvent doesn't dry white. I guess there is not an upper limit to the use of EDC either like the 10% limit on AA, and EDC will not cause crazing like too much AA can.
Other than that, it's all about joint prep. I would agree that WO40 is really slick to use but I've only used it with gussets on a repair.
EDC and AA both slow down the reaction time and "thicken" the solvent. Straight MC runs very fast and is hard to control.
For larger joints, James told me he uses the #16 needle and 2oz bottle from Craftics, and I've got one of these but lemme tell you I'm scared to use it. He told me that he can get around a 12' or longer joint before the solvent sets, by himself. The other nice thing I learned about EDC is that it makes solvent useable in more humid conditions, i.e. the solvent doesn't dry white. I guess there is not an upper limit to the use of EDC either like the 10% limit on AA, and EDC will not cause crazing like too much AA can.
Other than that, it's all about joint prep. I would agree that WO40 is really slick to use but I've only used it with gussets on a repair.
dmastracchio
New member
I have an acrylic squaring question....
I received some rough cut pieces of acrylic 24" x 24". When i cut them to height the pieces vary in width by almost 1/16th of an inch on all 4 sides. Basically, no sides are square. The original pieces were not square to begin with so when i cut them with a table saw.
What is the best way to go about this? Am I missing something when I go to glue the 4 sides together?
Any direction on where to go from here will be great.
I received some rough cut pieces of acrylic 24" x 24". When i cut them to height the pieces vary in width by almost 1/16th of an inch on all 4 sides. Basically, no sides are square. The original pieces were not square to begin with so when i cut them with a table saw.
What is the best way to go about this? Am I missing something when I go to glue the 4 sides together?
Any direction on where to go from here will be great.
woodnaquanut
Active member
First I'd check the saw. Is the fence parallel to the blade? It should be within 0.001 or 0.002 of an inch.
Next how are you going to do cross cuts? Sled is best and about the only way to go if the pieces are more than 12 inches wide.
With just the regular fence you can only make two sides parallel. You need to cross cut to get square.
Next how are you going to do cross cuts? Sled is best and about the only way to go if the pieces are more than 12 inches wide.
With just the regular fence you can only make two sides parallel. You need to cross cut to get square.
dmastracchio
New member
First thing I checked was the blade and fence. Grabbed a piece of wood and cut it perfectly fine.
The problem I think I am having is all 4 sides of the acrylic are not square. I actually need a larger square to confirm this...
So would cross cutting help? I feel like if i placed an edge up against the sled, it would cause the cut to be slightly off.
woodnaquanut
Active member
Square is tested by measuring diagonal corners. If diagonal measurements are equal, it's square.
Are any opposite sides parallel? Imagine a rectangle with sides 1, 2, 3 and 4. If 1 and 3 are parallel, doing a square cross cut on sides 2 and 4 will square it all. If the sled is not square to the blade, well nothing will turn out square!
Are any opposite sides parallel? Imagine a rectangle with sides 1, 2, 3 and 4. If 1 and 3 are parallel, doing a square cross cut on sides 2 and 4 will square it all. If the sled is not square to the blade, well nothing will turn out square!
Floyd R Turbo
Either busy or sleeping
I square on the router table. My router table is rather large (4'x8').
you can make 2 opposite sides parallel easily by running one side through until it's flat, then flipping and running the other side. Then take a high quality T-square and lay that down with the T on one of the parallel sides. Now take a reference piece (a strip of acrylic that also has 2 parallel sides) and double-stick-tape that down to the main piece along the long part T square such that the reference piece hangs off the side. Now you have a side that is 90 degrees from both of the parallel sides. Use the reference piece to square the 3rd side, then take the reference piece off and square the 4th side.
Verify by cross-measuring as woodnaquanut stated. Sometimes this need to be repeated a few times. If you have the ability to do it, double-stick-tape both end piece together and square them at the same time. If the are really, really close, say 1/32" off diagonally, call it good and make sure when you build your tank you keep these pieces oriented the same when you bond them in place and you should be fine
you can make 2 opposite sides parallel easily by running one side through until it's flat, then flipping and running the other side. Then take a high quality T-square and lay that down with the T on one of the parallel sides. Now take a reference piece (a strip of acrylic that also has 2 parallel sides) and double-stick-tape that down to the main piece along the long part T square such that the reference piece hangs off the side. Now you have a side that is 90 degrees from both of the parallel sides. Use the reference piece to square the 3rd side, then take the reference piece off and square the 4th side.
Verify by cross-measuring as woodnaquanut stated. Sometimes this need to be repeated a few times. If you have the ability to do it, double-stick-tape both end piece together and square them at the same time. If the are really, really close, say 1/32" off diagonally, call it good and make sure when you build your tank you keep these pieces oriented the same when you bond them in place and you should be fine
Phixer
New member
Polycast GP is what I've always used. Almost used Reynolds R Cast last time but opted for Polycast again. For solvent, the mixture Floyd gave is pretty close to what I obtained from a local shop. I still prefer 42 with the applicator squeezed into a large syrenge and applied that way. It's good to compair notes using both methods. I would have to say though that 40/42 does need something to bite into so the same perfectly smooth surface for solvent would not hold as well if using 40/42.
What do you mean, they all have their glue custom made?
Are you referring to solvent or 2 part cement? Asking because I've never heard of anyone custom making 2 part polymerizable cement. PS30 is the only other brand I can think of. I've had great luck with WO 40/42 as is. Every big tank I've seen uses it as is.
Wish I could post some pics of these tanks but havent been able to post photos on this site for some reason???
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Floyd R Turbo
Either busy or sleeping
Cyro makes their own 2-part as I'm sure others do, it's just that Weld-On (Scigrip) is just that well known.
Can anyone tell me if I can safely enlarge the slotted opening in the top of my Euro style Acrylic Hexagon tank? Pictures can be found in this thread:
http://www.reefcentral.com/forums/showthread.php?t=2318419
I'm worried about impacting the structural capability. If I can make the slotted opening larger, can I just use a hand held router? It makes me very nervous as it has a very polished edge and I'm worried about how cutting into that will work.
Thanks!
http://www.reefcentral.com/forums/showthread.php?t=2318419
I'm worried about impacting the structural capability. If I can make the slotted opening larger, can I just use a hand held router? It makes me very nervous as it has a very polished edge and I'm worried about how cutting into that will work.
Thanks!
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