Recent content by PAUL GRAHAM

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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Today's glass aquariums are built on two styles, rimmed, or framed, and rimless. A rimmed aquarium possesses a plastic one-piece molded frame at the top and bottom that fits around the perimeter of the glass and binds the perpendicular joints tightly. In larger sizes there are cross-braces, at...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Thanks to all you guys for your input on my project. This started out one way and went somewhere else. It's a better solution than the original, so I'm grateful for your interest. When visitors come to admire my fish, I'll point out the aquarium stand designed by a committee of physicists.
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Thanks Baluncore. The thin bottom strip of the front panel overlays the edge of the 1.5 inch floor and is screwed and glued to solid timber. This brings the floor out flush to the face of the front panel. The top edge of the front panel could be reinforced with a 2 x 4 lintel on the inside...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    berkeman, et al : Here is the design using plywood. Do I have this right? One thing I would be inclined to do, but not shown here, would be to double the front panel thickness, as the cutout is very large. A second similar piece 47.5 inches wide could be laminated on for a 1.5 inch total...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Using plywood on three sides would make a strong support and significantly simplify the design. Most commercially available aquarium stands not made of welded steel use this type of construction. If they are budget-minded they use particleboard. I would use 23/32" CDX or PIytanium Structural 1...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Herman: The aquarium does carry the load - empty. Put 640 lbs of water in it, if the support is not distributed evenly, the glass panes will be severely loaded, tensioning the silicone seals. The pressure will persist until the seal fails. berkeman: Yes, I have always done my electrical...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    There's a reason why my drawings look like that.
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    The above drawings should have sufficient info to convey what this thing is and how it's gonna get made. berkeman thought a sketch would help. This is the sketch. Whatever happens, it's on me. I'll gratefully accept any comment. My original post was an attempt to find out if I could use doubled...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Well you're right about that berkeman. After today's input I am starting working drawings. I'll have something as you suggest in a couple of days.
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Certainly not a substitute for glue. Joints are simple lap overlay. Contact surface area where upper platform frame attaches to leg is 18.375 sq in on one side and 26.25 sq in on the perpendicular side, and, similarly, 12.25 and 17.5 where base frame attaches to leg. A minimum of three...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    The base of this space-frame surrounds the perfectly vertical legs, 3" x 5" in section, with 2 x 4, having a perimeter congruent with the top, now 2 x 6, platform. Attachment of all 2-by members to the legs is by Timberlok lags, two lags at each end and staggered with those used on the members...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Actually, a 5/8" MDF panel goes on top of the space-frame and a 0.2" high-impact neoprene mat goes on this. The aquarium bottom is elevated by the thickness of its plastic rim. That rim is transferring the weight of a full aquarium to the space-frame and the mat eliminates point stresses. The...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Baluncore; As stated this is not assigned study, but a hobby project. I am a 78 year old retiree whose education is in historical geology and environmental engineering. I am not a PE and am not in training to become one. I know just enough about some things to frame an intelligent question on...
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    Undergrad Compare Bending Resistance of Dimension Lumber used as Joist

    Not homework as in "assigned" study. I am designing a post-and-beam table, 48" x 18", to safely carry an 800 lb static load (an aquarium), with legs in each of the four corners. Except for the tops of the horizontal elements (beams), there is no top surface. The weight bears uniformly around...