From: muratlanne@gmail.com   
      
   "Bob La Londe"  wrote in message news:v90fgu$38u14$1@dont-email.me...   
      
   I would love to have a nice telescoping heavy gantry crane, but I don't   
   need one often enough to pay the price for one as heavy as I would like.   
     I do have a metal building with a large I-beam across the center.  The   
   building is 60' outside dimension, but the unsupported beam (bolted   
   together in the middle at the peak with large flanges) is about 55 feet   
   eyeballing the dimensions.  Maybe less.  The incline is about 4 degrees.   
   ...   
   -----------------------------------   
      
   The gantry hoist I built for my sawmill is an 18' long track supported by   
   tripods at the ends and a moveable A frame at the center, which can be   
   stepped over long logs, up to 20' so far. I designed for 2000 lbs, then had   
   to upgrade for >4000 lb logs from mature oaks that were leaning toward the   
   house, they expand into sunny clearings. One blew down, away from the house,   
   so I lost confidence in the others.   
      
   A single wide flange beam would have been better than spliced sections   
   structurally but mine needs to disassemble into parts I can carry and   
   reassemble off-road by myself. The tripods adapt to uneven ground, indoors a   
   wheeled base would be better. I have a towable 1 ton shop crane instead.   
      
   Gantry hoists are usually 8' long, mine needed extra length to span the   
   bandsaw head plus the log pile and hauling trailer. My track weighs ~250 lbs   
   without the hoists and can be moved while assembled with temporary wheels   
   bolted under one end and a trailer coupler on the other.   
      
   I bought a 2 ton gantry trolley from HF for the upgrade and so far have   
   tested it to 3500 Lbs. On the sawmill two separate chainfalls have proven   
   useful. The second is a 1 ton that operates twice as fast, the 2 ton (not   
   HF) is tediously slow. Amazon had a 2 ton hanging crane scale for under   
   $100.   
      
   I assemble the track, trolleys and chainfalls on sawhorses and raise them   
   with a boat trailer winch at each end, the 2 tons are too heavy and awkward   
   for one man on a stepladder. With the upgrade the track hangs from G70 chain   
   joined with G100 hammerlocks. G100 chain has shorter links than G70 and is   
   more difficult to join into slings etc. I bought it at a logging equipment   
   supplier where I could try what fit together and what didn't, my multi leg   
   hardware store G30 chain assemblies could be copied in G70 but not in G100   
   rating. Apparently chain rated for overhead lifting is made from a less   
   brittle alloy that better tolerates shock loads like falls and electric   
   winch starts. Hammerlocks have ends that fit where shackles won't but they   
   aren't as easily assembled, especially on a ladder.   
      
   Perhaps you could suspend a carefully leveled beam track from your existing   
   structure to allow lifting and moving a load off a trailer and onto pipes or   
   machinery mice, then set it on the floor with a J-bar.   
   The important number for online calculators is Ixx, in inches ^4. It's the   
   link between steel beam dimensions in height x weight per foot and load   
   capacity calculation. I use pinned end conditions to simplify calculations   
   and disassembly for storage, and double shear on bolt shanks which is why I   
   modify the thread lengths. The L/360 live load beam deflection limit is to   
   avoid cracking wall plaster, not for strength. I had to exceed L/20 to   
   straighten one piece of the used pallet rack channels for my track, it may   
   have been 50KSI steel.   
      
   -jsw   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)