From: none@none.com99   
      
   On 8/8/2024 11:03 PM, James Waldby wrote:   
   > Bob La Londe  wrote:   
   >> 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.   
   >   
   >> I'm playing with the idea of putting a beam clamp on the I-Beam and   
   >> putting a chain fall on it about 8 feet from the support column on   
   >> that end.  With a 16' eve height a 15' chain fall should allow for   
   >> laying the hook on the floor. [...snip...]  Bridgeport Series 1 CNC   
   >> mill on a trailer in the shop right now.  Depending on where I look   
   >> it weighs between 2000 and 3000 pounds.  [...snip...]   
   >   
   >> My thought is the beam is certainly heavy enough if it was a short span   
   >> like a gantry crane, but being a 55 ft span I might be playing with fire   
   >> if I were to try a heavy lift near the middle.  I am hoping near the end   
   >> more of the load will be vertical on the support column.  [...snip...]   
   >   
   >> It would be a single (more or less) short duration load so that I   
   >> could lift the mill, roll the trailer out from under, and lower the   
   >> mill onto a heavy pallet, so it can be positioned with a pallet jack   
   >> and eventually set on the floor with my cherry picker (engine   
   >> crane).  The last part is how I moved, positioned, and set the South   
   >> Bend mill (which is over 3500 pounds).  The cherry picker won't go   
   >> high enough to lift the mill off the trailer.   
   >   
   >> I don't know how dumb my idea is, but I'm probably going to go for   
   >> it.  The load time would be measured in a couple minutes, but my   
   >> thought is something like this is either going to be strong   
   >> enough. Or it isn't. [...snip...]   
   >   
   > You might run a test, lifting say 800#, 1600#, etc while measuring   
   > mid-ceiling deflection, eg with a Bosch laser measure, then   
   > extrapolate to "safe" maximum weight.  Of course, if the deflection is   
   > too small to measure (eg <5mm) then probably no worries.  Or if it's   
   > several inches, lifting via the ceiling beam would be a no go.*   
   > It's the in-between deflection cases that would be harder to decide...   
   >   
   > Whether you can reasonably extrapolate also depends on how the support   
   > column at the wall is braced.  Given the 16' eve height, Euler   
   > buckling could occur without warning if the column's not braced both   
   > ways when you exceed critical load.  Also see***.   
   >   
   > * If ceiling beam lift is no go, you might end up using dual rows of   
   > stacked cribbing, eg crib a platform beside the trailer up to trailer   
   > height, move palleted mill onto platform, and use pallet jack to   
   > alternately take out layers of cribbing.**   
   >   
   > ** Say pallet jack has 3" min and 8" max to top of forks; and suppose   
   > 24" of cribbing between floor and mill's pallet; and 16" of cribbing   
   > between top of forks and pallet.  Raise jack a little, remove 4" of   
   > cribbing, lower jack 5", remove 4" of cribbing on jack, raise jack 5",   
   > etc.  Ends with forks under the pallet, not in the pallet.   
   >   
   > *** If the wall's well-braced you could put your beam clamp nearer the   
   > wall instead of 8' out, and have a winch line across the shop to hold   
   > the chain fall hook out from the wall.  [However, if the clamp were   
   > right at the wall I think resultant forces would be about 90% on the   
   > chain fall and 45% on the winch line, which sounds like a high enough   
   > sideways force on the wall to raise the possibility of some exciting   
   > video footage. ...  In the grocery store a couple of weeks ago, I   
   > heard one guy say, "How's it going, Bill?", and Bill replies, "Going   
   > great, just great!  But it's early enough the whole day could still go   
   > sideways."]   
      
      
   If the mills was already on a pallet I might be tempted to tilt the   
   trailer and slide the mill off the end with a pallet jack and some   
   ramps.  Still wouldn't give me a lift in my shop, but it would get the   
   mill off the trailer.  The distance from the column is dictated by   
   shelves, position of the mill (or other stuff in the future) on the   
   trailer, and the parking position options for the trailer.  I do have   
   toe jacks so cribbing it onto a pallet "might" be an option.  Haven't   
   looked yet if there is clearance for them.   
      
   There are perlins connecting the central beam and support column to the   
   front and rear beams and support columns.  Of course their are X cables   
   on one side to prevent extreme building shifting in high wind loads, but   
   their tension has never visibly changed.  Not even with 70 MPH winds.   
   There is also bracing at a number of locations to prevent beam twist.   
   Pulling from the bottom of the beam straight down, it doesn't seam that   
   beam twist would be an issue.   
      
   Each column is bolted to a giant steel reinforced concrete cube.   
   4x4x4ft maybe.  Might be bigger.  It was big, but it was a while ago.   
   The cube is part of the foundation, and the slab has fiber reinforcement   
   and the appropriate steel rebar and steel re mesh.  Tilting or shift is   
   very unlikely.  The slab is supposed to be six inches of structural   
   concrete, but I have drilled it in a couple places, and its possible   
   it's only 5 to 5.5 in a few places.  Except for the deliberate saw cuts   
   to prevent this 18-19 year old slab has no cracks.  I think the biggest   
   risk is the strength of the beam itself.   
      
   I tried using some of the online beam calculators to do basic worst case   
   calculations, but they are really a bit beyond me.  Well, beyond my   
   attention span anyway.  The plug and play calculators don't really do it   
   for me, and I just haven't been able to motivate myself to wade through   
   the lists of formulas on others.   
      
   FYI:  This is a commercial steel building rated for 100MPH+ wind loads.   
   No snow load was provided, because while I have seen snow here 2 or 3   
   times, it has always melted as it hit the ground.  Even hail disappears   
   very very quickly.   
      
   Your shade tree testing approach using a laser tape measure (or a   
   weighted string) is probably the best approach for me to do some basic   
   testing.  I just happen to have tens of thousands of yards of string   
   (fishing line) and a 600lb(ish) outboard on a stand almost directly   
   under the beam already.  Only a few feet off the intended chain fall   
   location.  I have to move the outboard anyway.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
      
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