SteveB wrote:
"Christopher Tidy" wrote in message
...

Steve,

Thinking about your project a little more, I would choose to alter the
design rather than trying to add a stand-off. There are simpler and
stronger designs possible, such as this for example:

http://www.hi-techedu.com/products/hfc14.htm


I had thought of that, but the vertical beam joins to the sonotube at that
point, and just sits on top. The pushing sideways and the leverage would
cause the approximately 7' vertical corner support to push off the top of
the Sonotube, or come loose where it is only nailed together. This is going
to be the point of attatchment for the lower standoff, but I will make the
bracket 18" long, and at a right angle so I can wrap the whole corner, and
attatch to post, facia, etc, and increase the distribution of whatever side
load from the flex is. I don't think it will be that much. Certainly not
as much as mounting the bottom support of a stiff leg to it.

Yes, you would need to ensure that the bottom bearing can handle the
horizontal force if you go for the "stiff leg" type of crane. But if you
use your original design without a stand-off part way down, your bottom
bearing will carry a horizontal force. It would be a good idea for it to
be capable of carrying a horizontal force anyway. If you can resolve
these small problems, and you don't need to lift bulky loads to the full
height of the crane, I think the stiff leg is the way to go because it
will be strong and reliable. If you stick with your original design I
would put one stand-off at the very top and one a foot below it, as
opposed to the way they're shown in your diagram. This will mean that
the vertical column isn't being bent at all, which is a good thing. I
think this is more important than having a stand-off in the middle.
Also, make the stand-offs adjustable so you don't have to force the
thing together in the first place!

Best wishes,

Chris