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Truss & Base Plates (Bolts)

Discussion in 'Lighting and Electrics' started by lqdsky, Nov 6, 2006.

  1. lqdsky

    lqdsky Member

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    I have 4 pieces of aluminum 12" box truss (10') that I would like to use totem with roboscan 918's mounted at the top of each. I'm having 3' steel plates drilled out. What type of bolts would I use for the floor plates? (Grade 8 bolts). I would also be adding additional steel plates for weight. Is there any thoughts as to mounting 918's (89lbs) to the truss might be a bad idea. Thanks in advance.
     
  2. Van

    Van CBMod CB Mods Premium Member

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    If you are having the plates cut I would suggest having four holes cut and peened < counter-sunk > from the bottom side then use Grade 8 stove bolts from below. Is that what you were asking ?? Oh yeah the four holes lining up with the holes on the end peice of the truss.
     
  3. ship

    ship Senior Team Emeritus Premium Member

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    for advice, in assuming it's a vertical "tower" type situation, 1/2 cheseboroughs mounting the fixtures to the truss have at least over C-Clamp or other types of clamp certain stability and not cutting into the truss advantages.

    After this on the "base plate" as I expect you are making to weight down the base, given your fixture does not sit atop the tower, you might want to go off center on the mounting to compensate for the weight. If nothing else and even if that, safety that tower off from above so it can't fall. There is a formula for what weight from above equals torque to be countered from below as a load and a at least 5:1 necessity for safety.

    For bolts, one on countersink would assume that the bolts holding truss to base plate will be wanting to be flush to the bottom of the base plate. In that way flat-head screws should be used. A black oxide or chrome/zinc plated alloy steel socket head (hex) cap screw is a suitable replacement for the standard hex bolt. Alloy steel screws are considered in common terms "aircraft grade" or grade 9 or 10 as opposed to the normal bolt ratings of grade 8 used for truss.

    A flat head alloy grade screw of at least 5/8" given it's the same size as your hex bolt you would normally use to attach truss together would be something to look into. Otherwise at times a alloy grade butten head screw is often also used as a screw type. Same strenght as say a socket head cap screw, lower cap of screw height. All stronger than a grade 8 hex screw but will tend to become the bearing point when sticking below the base plate.

    Recommended that you go flush bolts. This way nothing sticks out and you have a large surface area to distribute the load.
     
  4. sound_nerd

    sound_nerd Active Member

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    You might find that you will need to sandbag the morley mats in order to keep the truss from tipping over...but then again, with a bunch of steel plates you might be alright. The mats that we use are about 3'x3' for the 12" truss, and 4'x4' for the 16" truss....something to keep in mind is the size of your mat.

    -B
     

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