SteveB wrote:
For the engineers in the group, and those who seem to know of these things
.........
If you would like, e mail me at , and I will fax or
send you a jpeg of my drawing, and you can get it just right.
I DO believe this thing will work, and I am not going to use it to lift
things much heavier than a couple of suitcases or a few bags of groceries.
So far, I'm into this about $200, so it is not just a frivolous widget.
But, failure can cause heavy damage to my structure. I think if I stay less
than 200#, probably more like 100 most of the time, I shouldn't have a
problem. I would just like to be sure, and hear from someone who can
calculate such things.
Hi Steve,
As Bugs suggested, I suspect this is the best you'll get from this
group. There probably aren't many true structural engineers who hang out
here, and those who do may have reasons for not wanting to get involved
(ranging from boredom with structures through to liability). There may
be other Usenet groups where you'll find better help, but I can't
suggest any. There is also the regrettable tendency for people to be
non-constructive in their discussions on Usenet.
As has been demonstrated, one of the problems with your proposed
structure is that it isn't as simple as it looks. Its behaviour is more
complicated and less easy to predict than I thought, and probably than
Ned and Bill thought, too. One of my main reasons for suggesting the
"stiff leg" type of crane is that the analysis of the structure will be
much more straightforward and less open to dispute. I would attack the
problem by making some changes to the design (you should still be able
to use the materials you've bought) rather than trying to find someone
who's a professional structural engineer.
Best wishes,
Chris