Acrylic TNT FleXy rack??

Discussion in 'Home Theater Projects' started by MarkJMills, Mar 28, 2003.

  1. MarkJMills

    MarkJMills Auditioning

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    I'm ready to try my hand at some home construction with a FleXy rack, per TNT. I'd like to make the shelves acrylic, for both aesthetic and practical reasons; despite searching, though, I've not found any advice as to the specific problems associated with making and using acrylic shelves for this design.

    I'm also seeking advice about the thickness of acrylic that would properly support various equipment weights -- would 3/8" be adequate for lighter pieces of 10 to 20 pounds, or would 1/2" be more appropriate? What about equipment weighing up to 35 - 40 pounds? 60 - 70 pounds? 1/2", or would 3/4" be better for the heaviest pieces? The rack as planned would have an overall width of 24 inches, with either 5/8" or 3/4" threaded rods inset 1" from the ends of the shelves, thus about 20" centered would be suspended -- I'm concerned about shelf bowing as equipment gets heavier, yet for cost considerations wold like to use the least thicknesses of shelving that I can. Does anyone have any practical experience with these issues?

    The rack has grown into a monster; I need room for 7 components of greatly differing sizes and weights, and must leave some room for cooling and component isolation (Navcom and Vibrapod footers and air bases), so I'm up to a minimum of 50" long support rods (and that's without any room for new additional components!). I don't want to go any higher to make access to the top shelf mounted VPI TT easy -- thankfully I'm tall -- and cannot squeeze two racks into the limited space I have available. At that height, are there serious stability issues that should be addressed?

    Any advice at all would be appreciated -- and yes, I did email Arnold Cruz, whose acrylic FleXy is pictured on TNT's site, but have not yet received a reply. I'm hoping to order the shelves on Saturday at a local store that does nice work with acrylics, so any advice, especially re: cutting and shaping issues and the thicknesses required for given weights, is needed ASAP.

    Thanks in advance, Mark
     
  2. Dave Milne

    Dave Milne Supporting Actor

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    Mark,
    Shelf flexure can be calculated if you know the weight of the component and the modulus of acrylic. Since I'm an EE and don't use this mechanical engineering stuff very often, I've forgotten the fommulas. And to be precise, I believe you'd need to know the location of the "feet" on the gear. It's probably safe to say that they're about 17" apart.

    My gut feeling is that 3/8 is too thin. Since the thickness term is cubed in the equation (this much I can remember) 3/8 would have eight times the flex of 3/4. Unfortunately, 3/4 acrylic is indeed expensive.

    The other challenge with acrylic is polishing the edges. The saw or mill used to cut out the shelves will leave ugly, opaque edges. Polishing them up to crystal clear is a very labor- and time-consuming process involving progressively finer grades of sandpaper and ultimately polishing compound. The result, however, is stunning.
     
  3. Bryan Michael

    Bryan Michael Supporting Actor

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    try tempered glass.
     
  4. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    A 50" high 7 rack flexy with 3/8" acrylic doesn't seem like it would be very strong or stable.
     
  5. Geno

    Geno Supporting Actor

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    is there anyway you can run the thread along the run of the acrylic instead of out from the back?

    Im not educated on flexy so I cant really see how you are invisioning things. for acrylic, id suggest 5/8" or more with 40 lbs on a 20" run depends on how much live weight will be added[ ie cd's tapes beer cans whatnot]
     
  6. Brett DiMichele

    Brett DiMichele Producer

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    I think you may find that even 3/4" Arcrylic is not strong
    enough to support the weight. In the end you may need 1"
    or maybe 1.5" Arcrylic Shelves to support heavy amps and
    Procesors...


    And the stuff is NOT cheap.. a 1" shelf would be a couple
    hudred dollars and you need what? 7 shelves?

    I can see the dollar signs now....

    A couple other things to consider is that MDF is used not
    only because it is affordable but also because of it's ease
    to work with and the fact that it's a solid made up of
    thousands of thin layers of laminate and glue. This material
    is stronger than a solid material of the same thickness.

    Arcrylic is also hard to drill, it tends to splinter and
    crack easily when the drill exits the hole you need special
    bits to drill it without incident (sure you "may" get lucky
    with a normal drill bit..).

    And then as was mentioned the edges will have to be polished
    and depending on how coarse the blade was that cut the arcrylic
    out you may need to start sanding with something as rough as
    180 grit paper and work your way all the way up to 2000 grit
    and then it will have to be micropolished with something like
    Tan 3M Micro Glaze and then Pink 3M Imperial Microfinishing
    Glaze and then be waxed throughly...

    This just seems like one major headache to me.. It would be
    gorgeous if done right, no doubt about it.. But the cost and
    labor would be rediculous! [​IMG]

    I wish you the best of luck! [​IMG]
     
  7. Geno

    Geno Supporting Actor

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    sorry just checked out the tnt's flexy site, i see what you mean. i completely misunderstood. looks like arnold used 3/4" 'crylic. I suggest LEXAN if you can find it.

    if you live in a big town call a plexi supplier and see if they have specs on their product
     

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