How much can I safely lift on this structure?
I'm splitting this off from Christian's https://www.woodworkforums.com/f65/hoist-176037/ thread, because it's a bit different. I would like to ask people who have practical experience lifting heavy stuff from existing structures: How did you figure out that it was safe? Did you try to calculate forces? Do you have engineering knowledge? If not, what rules of thumb did you employ?
Now I know the safety aspect of lifting can get people worked up. Could we just try to keep it constructive and objective please? :)