I'm renting a house that was built about 10 years ago. The attached, finished garage is under the master bedroom. It has two large beams running across it, see picture.
The larger one is 6.5" wide x 18" tall, and runs the entire width of the garage. The smaller one runs from the garage door to the large one, about 3/4 of the garage.
I want to hang a "heavy bag" for punching, from the large beam. I tried to drill into the side of it, but my wood bit got about 1.5 in before hitting something too hard (masonry or metal). Tried this in two locations, same thing.
How can I hang this 80lb bag? My current plan is to attach a 2x4 to ten 75lb "E-Z Anchor® Twist-N-Lock(TM)" drywall anchors and attach the hook with some 1/4-20 bolts.
UPDATE: When I check the beam with a magnet, the lower 'edges' are highly magnetic. That's the rounded portions within 1" of the corner, running all the way along the beam. There are also spots mid-height every foot or so where the magnet sticks moderately, the texture looks a bit deformed at these spots.
UPDATE 2: Per @Craig, yes, the edges are metal drywall corner bead. The drilling was sideways. I'll post a pic of the drill hole tonight. I'm not too concerned about the landlord... he's friendly, it's behind the beam and I can spackle it up when I move out.