Steve B wrote:

"Grant Erwin" wrote in message
...

Steve B wrote:


Well, in the midst of all my other projects, I went out and in one day
completed my hoist davit project for my cabin. This uses a vertical
piece of 150" long 2" x 2" x .250" square tube. There is a 48" right
angle leg at the top with a diagonal brace that comes in at 21" on the
48" horizontal and 150" vertical. I have used one pin at top and bottom,
using a grade 8 1/2" bolt that will fit into sockets top and bottom. The
lifting point is approximately 3" in from the end of the 48" top
horizontal standoff.

Any predictions from the engineers in the group as to bending in the
middle of the 150" section with a 150# load? I really think that the
maximum I would lift with this is 21 gallons of water in the winter.
Mostly, less than 50# of groceries including the lift basket. Just a
convenience device to keep us from making several trips up and down the
steep stairs schlepping bags of groceries or "stuff".

A three phase ramp is being made as we speak, conforming to ADA
standards, and that will help a lot. Still, it will be nice to just pile
groceries or firewood in the lift, and lift 'er up.

I personally don't think it will flex enough to be a problem. When I get
the base footer poured, and make a 150# test lift, I will report the
actual lateral horizontal bending factor.

Anyone care to guess? Winner gets bragging rights. Place yer bets,
gentlemen. Will take a month or so. Going back up on the 19th, and a
few days to form and pour and cure the footer. This has been an ongoing
project, and it will take a while to complete. But, it's moving, at
least.

So much to do. So little time.

Careful, there, what you need to worry about (big time) is buckling on the
main vertical component. Might want to weld on a piece of flat bar on edge
to stiffen it or something. As is, it can suddenly fail and if you're
under it you can get hurt, almost got my leg broke one time when a similar
thing buckled on me ..

GWE


Thanks, Grant. I have been standing back and looking at this, and I EXPECT
bowing in the middle. How much, of course is going to depend on the load.
Since I don't anticipate loading it that much, I think I can live with the
bowing. HOWEVER, knowing myself, I will continue to increase the load.
Welding a flatbar strengthener along the edge is a great idea, it's just
that if I do it, I won't be able to measure the ACTUAL deflection. But
then, to accurately assess this, I would almost have to load until failure
occurs, then backtrack. I believe I will put a 1/4" x 2" FB stiffener for
about six feet, centered, and call it a day.

I don't want to do this again if it fails.

Steve



This is on the vertical member, mind you, NOT the horizontal one.

Machinery's Handbook has tables of max loading on columns. Worth checking, the
library has one if you don't, don't need the latest.

GWE