The thought actually came from the fact that I'm going to hang up a punching bag, but a much lighter one (15 kg). I was thinking of bending a plate into a belly shape that I'd screw in with two lag screws and run a loop with a nut through the belly. But while I was doing this, I started to philosophize a bit about what would happen if you were to drill through the entire beam and what could occur if you hang a load with arbitrary mass. It would be interesting to know where the limit in hole diameter and the limit in load go, even though it's impossible to answer without calculating for the specific case.
So the thought is more hypothetical...
So the thought is more hypothetical...
Well, you can of course calculate that. Wood is an anisotropic building material - which means it has different properties in different directions - but there are plenty of formulas for that, and you can even perform numerical analyses to see force concentrations around holes or bolt groups.
But in your case with the bag, you need to make sure the structural part the bag hangs from is really rigid when you hit the bag. I would build a frame between two roof trusses, glued and screwed with cross braces.
If you let the bag hang from only one roof truss and the bag causes the truss to start moving (swinging back and forth), it can't be ruled out that you might damage the construction.
But in your case with the bag, you need to make sure the structural part the bag hangs from is really rigid when you hit the bag. I would build a frame between two roof trusses, glued and screwed with cross braces.
If you let the bag hang from only one roof truss and the bag causes the truss to start moving (swinging back and forth), it can't be ruled out that you might damage the construction.