Is that how a boat lift is designed, so the mast sticks up well above the top of the crane.
You are correct about rules of thumb and safety margin. I figure my heaviest lift will be 1750 pounds or maybe 2,200 if I buy a full size Mill. So my plan is to buy a 2 ton crane for some wiggle room on capacity. 3 tons or higher the price rises steeply and so does the empty weight to push around out of the way.
Bill D
Boat lift and that coffin-lift some wag posted for humour are right useful goods. They have in common that they work strap or cable around long, but small-diameter rollers from along each long-axis side. The attachment to a load is passed UNDER, not from tackle above the load.
The concept has value here, because my ATTIC has too low an overhead for sane use of a 120 V electric hoist I also harbour.
It's the load of workpieces - or in my case, heavy transformers, Dee Cee motors, MG sets that run from 200 to 500 Avoir that the 750 lb max scaffolding plus a 1200 lb rated folding ramp - used like a drawbridge - manages - ground (off machinery skates) to truck or caravan deck height.
"Full size mill" ain't no 2,200 lbs. That only gits you a tiny BirdPort, if EVEN. ISTR they run about 2,400, Avoir?
The upper turret of my Quartet - a
light mill at 5205 Avoir - was too much for Adam's 3,000 lb electric FL to get to truck-bed height. We had to add help from his jib crane.
Putting it back together, here, I used a rented 8,000 lb FL. THEN it was mated to a sort of "hand truck" fabbed for the purpose, laid over on its "cleaner" side, pushed unto place with a long timber.
Re-erecting once past the door and overhead simply Old Skewl rigging work, one-man show.
4,400 Avoir or so of rectangular-table Alzmetall AB5/S column drill had gotten exactly the same treatment, same "Paul Bunyan hand-truck", 3/8" X 7" X 6-foot steel Ell as toe rail had two sets of holes drilled before I started is all.
The Drill press, too, had been hauled-home with the top separately palletized from the base.
These tasks only need doin' once a year or every FIVE or
more years.
So the point is that unless you are a DEALER yah do not WANT to carry the all-year overhead of lifting gear for a "heaviest" lift used only once in a great while at all. Lybarger's Corollary sez when you need the capacity, it will be the wrong type of gear for the tasking, anyway!
You do a bit of planning ahead, then
rent what you need every few years.
Or even engage a pro operator who uses that equipment every day, all day, all year, for many years.
That way, one has better, newer, and
more appropriate gear for the seldom-needed task. Also smaller, more convenient, less "always in the way" gear for the day to-day tasking you actually DO more often.
Helluva lotta furniture dollys, machinery SKATES, three types, plus a "steerable" 10k Avoir Vestil swivel-top, a pair of toe-jacks, other jack types, my easily stored goto. Other folk use a pallet jack as "mostly" universal jack of all trades.
Scaffold I needed for home renovation anyway.
One of the nicest and handiest recent additions is a hydraulic die cart. Ignorant H-F one has been more useful that a better-built one I don't have at all. Considering adding its bigger brother, and for the larger table more than the lift. BOTH are due DIY upgrade to better wheels and casters is all.
Same again, the 2-T "folding" engine hoist that has paid for itself a dozen times arredy. Though I'd RATHER have the wide-legged K-D (knock Down) take-apart "Bluebird", I can rent those cheaply enough.
And do, when on a go-fetch run.
Bottom Line?
MANY among us are already too DAMNED short of
space to be wanting to house an awkward gantry when timbers, skates, jacks, die-cart, or a folding 2-Ton hoist can be easily put away in far LESS space between needs and will cover whatever ain't
worth a forklift rental or a boom-truck callout.
2CW