From: muratlanne@gmail.com   
      
   "Jim Wilkins"  wrote in message news:v9jdo0$kv7a$1@dont-email.me...   
      
   >A tripod of 2" x 10' water pipe is stronger but difficult to set up because   
   >the center of gravity is so high.   
      
   Also the pipes alone weigh ~110 Lbs and connecting the 3 top ends on a   
   ladder is difficult and risky with only two hands, it has to be raised with   
   its top ends connected, more weight on top to fight. The neighbor loaned me   
   his 2" pipe tripod but after setting it up once and straining my back I made   
   my own from lighter 2-3/8" OD x 8' fence tubing, which has served very well.   
   I think he set it up while standing on a truck bed or the front of the   
   vehicle whose engine he was swapping.  Although EMT may be intentionally   
   soft enough to bend its elastic modulus is the same as any other steel and   
   that's what determines long column buckling resistance.   
   https://en.wikipedia.org/wiki/Johnson%27s_parabolic_formula   
      
   On asphalt or concrete the tripod needs ball joint baseplates which are tied   
   together to prevent spreading. Connecting the leg ends in a delta pattern   
   creates a tripping hazard, connecting the baseplates to lower the rope   
   requires ball sockets with enough depth to retain the balls at the leg   
   angle. For the gantry tripods where the load isn't between the legs a wye   
   rope pattern is less of a nuisance under foot and tightening one rope also   
   removes slack from the other two. When possible I guy the tripod top to   
   anchors because lateral pull or any foot slipping can bring it down.   
      
   So far a fence post acorn cap in a beveled hole has been close enough to a   
   ball joint. The point digs in and holds on dirt when a lighter load doesn't   
   require a baseplate. The only breakage was a puncture from a sharp rock in   
   the ground. The EMT ends are cast iron acorn caps too small to fit over the   
   tube, so I turned their OD down to fit snugly inside it. The water pipe   
   shear legs have hemi ball ends turned from a dumbbell.   
      
   I don't give load capacities to force you to calculate, measure and be   
   responsible for them yourself, as your construction or usage may vary from   
   mine.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)