georgeous Posted April 25, 2008 Report Share Posted April 25, 2008 Hi there, I am making a block and board type stand for my 96 litre tank (60*40*40, hope i figured litreage right) and have hit a bump. I was going to have 9mm ply under the polystyrene, but Mum thinks that this will be too thin. What are your opinions on this. The tank will have two block towers supporting it. Cheers, George Quote Link to comment Share on other sites More sharing options...
spoon Posted April 25, 2008 Report Share Posted April 25, 2008 mite be alrite as there wont be much of a gap between the blocks but a thicker board would be better Quote Link to comment Share on other sites More sharing options...
Johannes Visser Posted April 25, 2008 Report Share Posted April 25, 2008 Hi there, I am making a block and board type stand for my 96 litre tank (60*40*40, hope i figured litreage right) and have hit a bump. I was going to have 9mm ply under the polystyrene, but Mum thinks that this will be too thin. What are your opinions on this. The tank will have two block towers supporting it. Cheers, George Mum's are always Right! Quote Link to comment Share on other sites More sharing options...
smidey Posted April 25, 2008 Report Share Posted April 25, 2008 Mum's are always Right! not when it comes to boys stuff, buliding, cars etc How far between the blocks does the ply have to span? Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 25, 2008 Author Report Share Posted April 25, 2008 At a guess, the gap would probably be about 250mm? Centred, anyway. But haven't bought anything yet. I could alwasy get thicker ply, or maybe double up the current thickness. I was also thinking about placing two pieces of wood (it looks at bit like chipboard, but it is smooth, and more fuzzy, if you know what I mean.) on top of the blocks, to help with the weight distribution. And JV, Dad said that theoretically, I didn't need any wood under it, because it wouldn't be spreading the weight Thanks, George Quote Link to comment Share on other sites More sharing options...
smidey Posted April 25, 2008 Report Share Posted April 25, 2008 it'll be easier to get a piece of 17mm ply & be done with it. go to scooters plywood supplies on commerce st & tell him what you need, he'll most likely have an offcut Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 25, 2008 Author Report Share Posted April 25, 2008 Been there, done that, but I asked for the 9mm. I am in Waihi ATM, and won't be gettin home till Sunday evening. I will have to go again though, but I can't really take any ply home on my bike :roll: . I was going to buy a quarter sheet, and then cut up the other half (about 600*700) into shelves, to go under the tank. Do you think I should use it as the main piece too? Quote Link to comment Share on other sites More sharing options...
smidey Posted April 25, 2008 Report Share Posted April 25, 2008 Been there, done that, but I asked for the 9mm. I am in Waihi ATM, and won't be gettin home till Sunday evening. I will have to go again though, but I can't really take any ply home on my bike :roll: . I was going to buy a quarter sheet, and then cut up the other half (about 600*700) into shelves, to go under the tank. Do you think I should use it as the main piece too? 17 will be alot stronger than 9, 5 laminations of wood instead of 3. Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 25, 2008 Author Report Share Posted April 25, 2008 Yep, but wouldn't 6 be better than 5 Or won't that happen? Quote Link to comment Share on other sites More sharing options...
smidey Posted April 25, 2008 Report Share Posted April 25, 2008 Yep, but wouldn't 6 be better than 5 Or won't that happen? yep, thats 19mm. bigger the better! Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 26, 2008 Author Report Share Posted April 26, 2008 Awesome, but isn't that 18mm Quote Link to comment Share on other sites More sharing options...
smidey Posted April 26, 2008 Report Share Posted April 26, 2008 Awesome, but isn't that 18mm nah, mdf is 16 or 18 & ply is 15, 17, 19, 21 ...... Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 26, 2008 Author Report Share Posted April 26, 2008 :-? so is this the double up, 2 sheets of 9mm ply, or the ply with MDF (it isn't MDF anyway I don't think) underneath?? Quote Link to comment Share on other sites More sharing options...
smidey Posted April 26, 2008 Report Share Posted April 26, 2008 ply has the two outside faces then extra layers in between to increase the thickness. ply is very strong to to the glue used & that each layer is rotated 90 deg which leaves the grain in the opposite dirrection & thus cause rigidity. "3 ply" is 4,7 & 9mm thick. "5 ply" is 12 & 15mm "7 ply" is 17,19 & 21mm, "9 ply" is 25mm & "11 ply" is 33mm. These are made of layers of 1 to 3mm wood & glue. plywood is wood all the way through. you can get "veneers" that are MDF or particle board that have 2mm of real wood veneers on the out side. that is what we use for timber panels for kitchens that have solid timber doors. Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 26, 2008 Author Report Share Posted April 26, 2008 Ok... so what is 9 times 2?? Im confuzled Quote Link to comment Share on other sites More sharing options...
smidey Posted April 26, 2008 Report Share Posted April 26, 2008 Ok... so what is 9 times 2?? Im confuzled the 2mm layers are on the veneer sheets not ply wood. The thickness of plywood is the wood plys which can be 2 or 3mm with the thickness of glue between each ply or layer. Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 26, 2008 Author Report Share Posted April 26, 2008 I think I have it now. So are you assuming that I will glue the two sheets together?? Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 27, 2008 Author Report Share Posted April 27, 2008 So you think that how thick will be thick enough Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 27, 2008 Author Report Share Posted April 27, 2008 I get it, you think I was talking about the a single layer of 19mm ply, but I was tanlking about two 9mm sheets on top of each other. Does anyone else have any thoughts on this?? Seeing as the ply won't bend (because the glass goes all over the sheet, and the glass doesn't bend) won't pretty much any thickness do?? Cheers, George Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 28, 2008 Author Report Share Posted April 28, 2008 Ok, have been out and bought 6 blocks and a 1/4 sheet of 9mm, 5 ply, ah, ply. Blocks are unfortunately wet, and are currently drying in the carport. I will stick some MDF under each tower to help spread the weight. Have also sandpapered down the ply, so just gota wait for the blocks to dry out and the final O.K. from The Allpowerful, Allknowing Mother ( :roll: ) Can't decide if I want to upgrade the Angels or not. Will go for a look at silica sand soon. Sounds expensive :roll: Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 29, 2008 Author Report Share Posted April 29, 2008 mmm blocks are still wet, apart from two, any ideas how to dry them out?? We are currently using a hairdryer :roll: Quote Link to comment Share on other sites More sharing options...
Caryl Posted April 29, 2008 Report Share Posted April 29, 2008 Sit them in the sun 8) Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 29, 2008 Author Report Share Posted April 29, 2008 Will do that as soon as the sun comes out :roll: It's had a bit off a rain today unfortunately Quote Link to comment Share on other sites More sharing options...
Warren Posted April 29, 2008 Report Share Posted April 29, 2008 This tank's bottom glass will have a peak deflection of approximately 0.62mm. The wood that needs to be placed under the tank needs to be able to support approximately 1/3 of the total weight of the tank with less than this deflection to have much support of the glass. I don't have the strength figures for commonly available plywood so cannot calculate the deflection of the wood for you. To add significantly to the strength of the bottom glass of the tank you should add the maximum practical thickness. The thicker the wood, the less stress on the glass as the wood will deflect less. As you already have 9mm wood and a 1/4 sheet, there should be enough to stick two or three layers together for really good strength. If you do this, make sure to glue the wood together as this will make it around 4x stronger if two bits are glued together (18mm) and 9x stronger if 3 bits are used (27mm). You can never have too much support for your tank... Quote Link to comment Share on other sites More sharing options...
georgeous Posted April 29, 2008 Author Report Share Posted April 29, 2008 Thanks for that Warren, but I can't understand a thing :lol: Care to explain at all? Quote Link to comment Share on other sites More sharing options...
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