Need ideas for a rotating log boom for log cabin

[PhysAssist]

Well we got a good start on the addition yesterday. It turns out that the logs aren't all that heavy. They are kiln dried pine, up to 16' lengths.
I'll put up some pics later.
thanks again for all the input, I may need something in the future.
dave

Glad you got it started!

Sometimes that's the hardest part.

When we had to rebuild our pond raft and put new barrels under it for floatation, we used an 'A' frame made from three of the tallest straightest cedar logs we could find and used a manual winch to hoist and secure the 'A'' frame and an electric winch to lift and lower the raft on a cable with a chain connecting to eye bolts on each end.


It took a bit of trial and error to find the balance point, but lifted it easily...

It's made of 2x 10's and decked with 2x6's with standard floor construction using 2x8 joists, and is 10'x 12' so it's massively heavy.

The 'A' frame crane is just a wider based version of a 'gin-pole' which doesn't require a fixed hinged mounting point- we pinned the bases in place with rebar thru triangles of 2x4's and into the ground.

 

[sparc]

take a look at these links simular to what your trying to do,
Boom Derrick

We built something like this on a job when we needed to unload some crates of cast iron soil pipe fittings. We used a couple lengths of 4" sch 40 pipe, welded up a turntable out of some scrap steel on the job, and clamped the whole thing to a 12" WF column in the building. We set the mast so it was off the corner of the column which let it swing close to 270 deg. We used two chain falls, one to raise/lower the boom and the other for the load. the 2 of us threw it together in about 2 hours and had the truck unloaded in about 30 minutes after that. Every truck that came on site after that we saved loads of time unloading.

The chain fall to control the boom height was mounted vertically along the mast. The top hook of the chain fall was connected to a 1/2" wire rope that ran through a snatch block mounted at the top of the mast, and then went on to connect to the far end of the boom. When you operated the chain fall it would rise up and down, the wire rope length was adjusted to give the necessary travel in either direction.

 

[BHD]

been looking at something similar for a different purpose

but here are some links that may help
http://www.agkrane.com/
http://www.beavervalleysupply.com/sectionc/agkraneqh.htm

http://www.craneblogger.com/wp-content/uploads/2011/01/817949.jpg

tractor with crane unload tree branches out of trailer. timber industry. material for biofuel production. - 2204044 | Shutterstock Footage

then the thought crossed my mind the logging cranes that are on some logging trailers,
OCALA HARDWOODS & SAWMILL BY ROBERT ROSS OF WOOD CRAFTING WOODWORKS: LOG LOADING WITH TRAILER CRANE

about two thirds of the way down, on the page a derrick
GANSG- Open Cast Mines and Quarries

even a three point boom crane with electric winch on it, http://www.abollo.eu/kaldirma-vincler.html more than this but a simple tube that extends up some distance that a pulley could be attached to and a winch, even a hand winch if cost was a super issue,

(I did see a grain auger lift, that had a tremendous cable movement on it using a hydraulic cylinder, it had a cylinder with about 4 pulleys on each end of the cylinder and the cable was wrapped about the pulleys so when retract the cable was at the longest and when it was extended it would multiply the travel by the number of pulleys on the ends, so a 48inch cylinder would move the cable about 8 feet on each pulley, http://www.grainaugers.com/_uploads/Westfield/Products/Images/9_LargeImage.jpg