Grigg...I immediately picked up on that word "shear" as well that R-Bo used. Another instance of anyone who ever built anything not understanding the basic laws of physics and engineering. The moment arm X the weight of the load = the ft lbs required to lift. Example: a 600 lb engine to be lifted at 4' from ctr = 2400 ft lbs needed to lift. There should always be a 50% safety factor added. And that does not even consider the tipping moment of the base. So in this example the crane needs to be able to withstand 3600 ft lbs at the point of failure.
Since I don't know the materials or dimensions used in the Gantry I can't consider it further except to say that the columns appear adequate but the horizontal connecting piece appears (?) light. Might be steel or painted wood? Looks nice however.
No criticisms here, just please always be sure all of you understand what is involved so you can come back and tell us how it all went because we don't have an obituary column.
