In article <1021@proton.UUCP> email@example.com () writes: >Is my plexiglass tank bowing too much? > >I recently got a 50 Gal acrylic (Sea Clear) aquarium. The plexiglass >thickness is 1/4 inch on all surfaces. When I fill it with sea water, the >large surfaces (front and back) bow out 1/2 inch compared to the empty tank. > >Frankly, I am a little bit worried, this being my first plexi tank. > Up to 1/2 inch in the middle is normal for a 1/4 inch tank. Any more may not be normal. >QUESTION:is the bowing normal for plexi tanks,and does my tank flex more >than others? Is it in any danger of breaking? Is 1/4" the normal acrylic >thickness used on 50 galon tanks? I am using it, but I'd rather empty it >rather than risk 50 gal on the floor. The risk is minimal - no different that any other tank (glass or acrylic). 1/4" is a normal thickness for a tank upto about 20" tall. There are many different grades of acrylic, all which have very different properties. This makes it very difficult to ask if any such number, say 1/4" is acceptable. Be vary careful when you compare Glass to Acrylic - the numbers really are irrelavant. My company used 1/2" acrylic to make 30" tall 600 gal tanks. Is this safe? Absolutely! Is there any bow? Less than most 5/8" plate glass tanks. ie: my personal glass 220 (30"tall) bows over 1/2" and it is made from 5/8". >Costin Radoias, EE If you have any more questions, I'll be glad to answer them. Jonathan Burke AquArt Custom Aquariums
Hi, I just finished reading the adhesive section under ftp reefkeepers in the diy section and realized that there is a lot of confusion out there. Since I work for Rohm & Haas, the makers of Plexiglas, I thought I might spread some light on the subject. First let me say that I do not personally work in the acrylic department, but have some experience from working with people in that department and I am a soon to be materials engineer. Also, my company is NOT liable for any of this information. Acrylic or Plexiglas is actually PMMA (Poly Methyl Meth Acrilate). When things are bilt with it, it is generaly not "glued" but solvent welded. With glueing the adhesive itself forms the bond between the pieces and permanatly stays there.Solvent welding actually works quite a bit different.The pieces of Plexi are placed together in the desired fasion and the solvent is let to wet or "bleed between the two pieces. They are then left to cure. What happens is that the solvent dissolves the PMMA (in a small region). The long polymer molecules from each piece entagle with each other while they are in solution with the solvent. The solvent then slowly evaporates leaving behind a joint of just PMMA with no adhesive. The solvent we most commonly use is MDC (Methelene Di-Chloride). Also I wanted to note here that PVC "glue" is mostly a solvent with some other additives and works in a similar fasion. Again, I am no expert craftsman with Plexiglas, but I do know someone that is. I am going to ask him if he wouldn't mind directly answering some questions to the net, but I can't make any promises. If he will, I'll post his logon ID. Hope this clears up some confusion. ------------------------------------------------Frank Fatato MAHFBF @rohvm1.rohmhaas.com "My man, pots and pans" J.M. ---------------------------- My employer is NOT liable for anything posted here.
firstname.lastname@example.org (noel patrick moore) writes: >Does anyone have any information on building tanks . >I have been keeping fish for years and would like to start >building my own tanks now. > What kind of glass is best ? > What kind of silicone ? >Any information greatly appreciated. Plexi-glass is best! One 10'x5' sheet of 1/4" can be had near $100. With this you can build a tank that with a 5 foot front and 20" x 20" depth and height. 1/4" will work but if you can get 3/8 it's better but harder to bend. A 8'x 4' sheet costs around $70. It can build a 4 foot by 16" by 16" tank or other pertubations. ________________________________________________ | 4 feet | | | | 1 Bottom | | 6 | 16 in. |-----------------------------------------------| | ! ! | | ! ! | |8 ! ! | | ! Top ! Back | |f ! ! | |e ! 4 ! | |e ! ! | |t ! f ! | | ! e ! | | ! e ! | | ! t ! | | ! ! | | ! ! | | ! ! | | ! ! | | ! ! | | ! ! | | ! ! | | ! ! | | ! 16 in. ! 16 in. | | !---------------!----------------| | ! | | ! Waste | | ! | | ! | | ! | | 16 in. ! | ________________________________________________| I recomend a heat gun for bending. Take plenty of time and have fun. --Wade
In article <2qtbpeINNrds@srvr1.engin.umich.edu>, email@example.com (NATHAN R EIDE) writes: > On this subject, what thickness would you need to build an acriliyc (spelling) > tank - and where do you find the plexiglass? Not the same stuff you > buy at a hardware store - is it? > Thickness will depend on the volume of aquarium you expect to build, if you look at the "factory built" units you will notice that they are mostly 1/4" or 3/8" thick. You can find Acrylic, trade name plexiglass (Rohm & Haas) at any plastic supply outlet. It is the same stuff you can find at a hardware store, but I would guess at twice the cost. You also do not have much of a selection in the hardware stores, if you want to do a professional looking job, you will need a long length of acrylic so you can "wrap" the front corners. For the aquarium I built, I had to special order a 12' length of 3/8". You can get any size you require, up to 20' ($$$) but most distributers don't stock any much over the usual 4 x 8' sheets. If you wrap the corners you will need to put together a strip heater to heat and bend the acrylic, the same supply house should have these in stock. There is a technique for bending acrylic that you will need to master first (you wouldnt want to destroy $200 worth of acrylic) once the bend is made, there is no going back, as the heated area has been distorted, and will always be visable. You need to mark each edge where the bend will be and line this up on the strip heater. The acrylic should be about 1/4" above the heater, dont let it touch or it will melt the surface and "mark off" on the acrylic (very ugly). I run a 4' length of 2x4 through a dado on the table saw to make trough that the heater sits in. Space the other end of the acrylic sheet with another 2x4 to make it level. Let the first side heat for about five minutes and flip the panel over. This is *important*, you must flip the panel over and heat the opposing side to get a clean bend, and you must not leave any one side on the heater too long. If you do bubbles will form in the heated area as the acrylic out gasses as it breaks down.(very ugly again) After 10 minutes or so, you will feel the short end of your panel getting "loose", support it with one hand, and wiggle it to judge how the heating is progressing. Keep wiggling and bending further and further until you feel that it will make a 90 degree bend with no effort or "fighting back". At this time pull the sheet from the heater and make the 90 degree bend. I built a 90 degree fixture that I could hold the panel against while it cools, it takes about five minutes before it sets. Tip: make sure that the bend that will become the outside of you aquarium is the last to see the heater, the outside bend has farther to travel on the radius and should be the hottest. Use a thickened acrylic adhesive, not the capillary cement. practice your bends with scrap and practice your glue up (too much glue looks very ugly also) too little leaves voids and possible leaks. You won't be able to get those nice 2" radius bends you see on the better aquariums because the manufacturer builds custom heaters that are 2" wide, the only heaters available to us are 3/4" (though you could layout two and get a 1 1/2" bend. I havent tried this though). Practice, practice, practice...get the technique, its not too hard to learn, and you will have a beautifull aquarium you built yourself. KS@Lilly.com
In article <firstname.lastname@example.org>, email@example.com (Chuck) writes: |> From: firstname.lastname@example.org (David Jacobson) |> |> Finally, you should take along a microfiber cloth (or maybe a small |> bottle of Windex and some Kleenex if you don't mind attracting |> attention) and clean the window where you are going to be shooting. |> You said the aquarium will not yet have opened, so maybe it won't be a |> problem, but normally, the windows are covered with hand prints |> and kids' nose grease. |> Just don't use windex on any plexiglass our you will have just messed it up royally (it will glaze).
email@example.com (Brian Hunter) writes: >In article <1993Feb8.firstname.lastname@example.org> email@example.com (daniel.a.parker) writes: >>IS THERE A GOOD REFERENCE ON HANDLING ARCRYLIC? HOW DO YOU DRILL IT >>SO THAT YOU DON'T GET SMALL CRACKS? The manufacturers hand out sheets on the finer points of handling and machining acrylic. I've seen them at a real plastics place (as opposed to a hardware store that happens to sell acrylic) for free. If you can't find a store that has them, you might try contacting a manufacturer directly. >Very carefully, I have found water cooling while drilling helps. You >also need a specially ground bit. You need neither if you can locate a drill press. Keeping the bit absolutely steady has been the most important thing in my experience. In particular, as the bit drills out the last millimeter or so it seems to try to "break through", catch in the acrylic, and try to jerk the piece around. If it does this, it will almost certainly crack the acrylic. Best is a drill press and clamp; if you don't have the equipment, you should try to come as close as possible. You should also drill a small guide hole before drilling with a larger bit unless the hole you want is tiny. I drilled a trickle-filter drip plate with 120 counter-sunk holes using wood bits with no problems at all (other than boredom after the first few dozen holes). Finally, it seems that the ultra-sharp premium-quality bits are actually more prone to catching and jerking than lesser and duller bits. On the other hand, if the bit is too dull it will melt the acrylic rather than drilling it. A nearly but not quite sharp-as-new bit is probably best if you use wood bits. -- Dustin "I contradict myself? Very well, I contradict myself. I am vast; I contain multitudes." firstname.lastname@example.org From: email@example.com Date: 22 May 92 15:00:16 GMT
Measured light transmission of standard soda-lime glass (typical window/aquarium glass) and poly(methylmethacrylate) acrylic - "Plexiglass" brand. Wavelength (nm) % transmission Glass acrylic 600 90 90 500 92 90 400 93 89 375 90 69 350 78 9 325 20 0 300 0 0 The thickness of the glass was 3 mm (glass thickness is metric in Canada) The thickness of the acrylic was 1/8 " (ca 3 mm). Borosilicate glass (pyrex) is transparent well out into the UV (at least to 300 nm) but I don't know if it is available in sheets at a reasonable price. Different types or brands of "acrylic" may be different. Kirk Marat Dept of Chemistry U of Manitoba From: firstname.lastname@example.org (Miller Douglas W.) Date: 3 May 1994 17:52:46 GMT
I've just received some booklets published by the manufacture of plexiglass (acrylic). Some time ago there was a discussion on how to remove scratches for acrylic tanks, I thought I would relay what they had to say. <Random comma generator on> Before sanding, buffing, or polishing clean the plexiglass carefully. Small scratches can be hand polished using a soft flannel cloth a good grade of automotive paste wax. Deeper scratches can be sanded,however, this will cause a variation in thickness which results in optical distortions. If a buffing machine is used it should operate at 3000 to 4,500 surface feet per minute(SMPM). (1/4 buffing wheel diameter in inches multiplied by the spindal RPM). The buffing wheels must be clean before starting (preferably new). If an abrasive compound is used to remove scratches a different wheel should be used for the final buffing as some of the abrasives will remain in wheel even after cleaning. If the part has been deeply scratched or sanded an abrasive coated wheel is used first. The abrasive is a standard polishing compound composed of very fine alumina or similar abrasive and tallow. The plexiglass sheet is next brought to a high polish by a soft, loose buff with no abrasive or tallow is used. These cleaning buffs should be very loose and should be made of imitation chamois or cotton flannel. The wheel should be 10 to 12 inches in diameter and run at 3,000 to 4,500 SFPM. A hand-applied coat of wax may be used in place of buffing on the finish wheel, if desired. If sanding is needed first try 600 grit sandpaper wrapped around a rubber-padded sanding block. Sand over the scratch covering an increasingly larger areas. If this does not readily remove the scratch step down to 400 grit sandpaper. Sanding should be done in directions mutually 30 degrees apart, producing a diamond pattern. If 600 grit is used, step back upto 400 grit once the scratch is removed. Mechanical sanders should be avoided, since the heat generated can cause distortions and possible discoloring. Do not use belt or disk sanders, if a mechanical sander is used it should be water or better yet oil cooled. Once sanding is completed buff the sanded area. I personally can not attest to the effectiveness of these methods and recomned trying the methods, and buffing compounds/sandpaper grits on a piece of scrap before fixing a scratch on an expensive tank. Booklets on acrylic fabrication, forming, and painting are published by: Technical assistance phone (215) 785-8290 AtoHaas north America Inc. Independence Mall West Philadelphia, PA 19105 AtoHaas Canada Inc. 2 Manse Road West Hill, Ontario Canada M1E 3TP PS I'm currious if you have an acrylic tank, what size is it and what did it cost you? I'm thinking of buying or building myself one, depending on cost and I was wandering what was popular (looks good) and the dollar amount involved. E-mail me at email@example.com I'll be hear untill the 13Th. (hum... graduating on friday the thirteenth) Doug Miller If I don't get the chance to post again thanks for I of the great info and answering my dumb questions.
In article <firstname.lastname@example.org>, email@example.com (Kristi Bittner) writes: > : For the inside, if you don't want to remove the water nor the fish, you can use > : a kit called Surface Restoral Kit made by Micro-Surface finishing products Inc. > : They have some fine wet/dry sand paper called Micromesh. I have yet to try my > : kit but my 55g acrylic is badly scratched by my big dogface puffer. > > : I believe the above-mentioned kit is the only tool you can use to remove inside > : scratches without draining water. Correct me if I am wrong. > > : BTW, I will use the kit on a marine water tank...... > > I've never heard of this before... let us know how well it works, pleeze!! > > thanks in advance, > Kristi Okay, I finally used the product Micro-mesh (or Acrylic Aquarium Restoral Kit) to polish out nearly 95% of all the inside scratches of my 55g acrylic without draining a drop of water nor take out any marine fish. It is kinda time-consuming at first (at coarser grade micro-mesh paper) but as it goes on, its much easier for the finer grade polishing. The water will be very cloudy but the guys at Tenecor told me that these loose particles are inert to fish. The instruction of the kit does suggest removal of fish before polishing though. Anyway, I changed like 40% of the water afterwards and my fish are still doing excellent now. If my fish show any signs of discomfort, I will post to warn others ASAP. I bought this kit from Tenecor for $34 and the exact same thing runs for only $24 at TFP!! I believe you can use very fine wet/dry sandpaper to substitute for these micro-mesh. This kit is only enough to polish one face of a show 55g. I could not believe that it is possible to polish out inside scratches without draining water so perfect. It is now like a brand new tank. The scratches I had before polishing were from: 1. Fine sand being trapped between algae scrubber and acrylic glass. 2. Decorative corals falling onto the acrylic 3. My hugh puffer keep scratching with his beak. Eddie
In article <1995May11.firstname.lastname@example.org> email@example.com writes: > In the trade this is usually called "Flame polishing", and yes, it has been I've been experimenting with flame polishing the edge of acrylic (1/4") using a small butane "pencil" torch. I don't see any discoloration of the acrylic which you indicated is a problem with oxy-acetylene flames. If I get it too hot, I get the bubbles you described. If I don't get it hot enough, no polishing happens (of course). In between those extremes, I get polishing, but the edges of the edge (the corners) become proud of the face of the sheet. Here's an approximate picture, with the effect exaggerated. _____ _---_ | | /| |\ | | => | | | | | | | | | | | | | | Oops, that picture's terrible. I hope you know what I'm talking about though. Another problem, which you can see in the picture, is that the edge, which was flat (though rough) before the polishing, became curved. Thus, flame polishing (using my bad technique anyway) isn't suitable for preparing the edges of acrylic for butt joining. I find sanding to be more successful, though annoyingly tedious. The edge left by a spiral bit in a router is good enough, but doesn't make as perfect a joint as if I sand. (I'm doing my cementing with methylene chloride applied by the capillary action method, through a little needle.) Please advise. :-) -- Chris Paris <firstname.lastname@example.org> Support censorship -- go to CMU For information see http://www.cs.cmu.edu/Web/People/kcf/censor/
In article <email@example.com>, Jason Madison <firstname.lastname@example.org> says: > >Sorry about wasting bandwidth, as this is a repost, but I keep forgeting >to put a subject down, so I bet most people ignored my earlier post >(with good reason). > >I have been thinking about building my own acrilic tank. I looked in >the FAQ, but couldn't find much info on building acrilic tanks (only >wooden). Is there a special grade of acrilic that must be used for >aquariums? I went to the hardware store and found 1/4 " acrilic that >looks extremely clear, and I could buy enough for a 4x2x2 with only >$100. Can anyone tell me how thick the acrilic needs to be (I know its >stronger than glass), and how to seal it. I know you use a solvent >sealer, but do you need a special kind for aquariums or can I get it at >the hardware store with the acrilic? If its as simple as it seems, why >havn't I heard more about doing it? > >As always, any info at all would be appreciated. > >Jason Madison > > > > I would consider trying to get 3/8", unless its lexan. Lexan is much stronger than plexiglass, unbreakable, and about 3 times? the p[rice I know that 1/2" glass would be needed for a 24" high tank. I don't have any figures on plexiglass in front of me, but if you know that plexiglass is <30% stronger than the glass then 1/4" would be fine. Also, it would be unwise to make it square. the weakest points will be at the seams. You can eliminate corners (weakpoints) altogether by bending the solid piece of plexiglass at the corners. This will require the correct tools. I think they're called strip heaters/benders (basicaly a 4" by 3' hot pad to heat a section of plexiglass to a mallable temperature). Then you can overlap the back seams by about 1". I was planning on building several until I got the bugs worked out, then ******* the plans. But I won't be in a position to do that until the end of this year. Use the regular plexiglass glue stuff, but go over all the seems with silicone to ensure the watertightness. Hope I have helped. Steve.