From: none@none.com99   
      
   On 8/15/2024 6:21 AM, Jim Wilkins wrote:   
   > "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.   
   >   
      
   I just don't find much good salvage steel around here, although to be   
   honest I've pretty much quit looking.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
      
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