I am looking to hang a 100 pound heavy bag in my basement. I have 2 ideas and want to get some opinions on them and other ideas that may have worked for others. I am trying to hang it from 2 ceiling joists spaced 14 and 1/2 inches apart.

My first idea was to screw a 2 by 4 up across two, maybe three joists then screwing my heavy bag hanger onto that 2 by 4. (Im thinking this might even rip straight out due to the fact that i have to screw UP into the ceiling joists.) I may even use a 2 by 6 to get more screws into the joists if i decide on this setup.

My other idea is a bit harder to explain so bear with me. I also thought of cutting a 2 by 4 to fit in-between the joists. but before screwing it up there i was going to cut two small 2 by 4 blocks then screw those into the bottom of the first 2 by 4 on each side. (So the load bearing 2 by 4 has two blocks to sit on for extra support.) Then screwing that whole setup in-between the ceiling joists. My thoughts on this setup is that it may be sturdier due to the screws being horizontal rather then vertical and if i really wanted to make sure it wasnt going anythere i might even be able to use nuts and bolts rather then big screws.

I really cant afford to buy anything else, which is a shame cause i did see a bag hanger thats specifically for hanging in-between ceiling joists and can only afford to jerry-rig something

Yea I wouldn't do the simple 2x4 route. And look at as much support and as many screws as you can get in. I've hung mine repeatedly from the ceiling joists (sp?) and keep knocking that thing off. It pulls the wood out in chunks. Looks badass and all when it happens haha, but mainly it isn't a strong hold. I suppose I could have gotten deeper setting screws but I don't actually use it much.

What if you guys drilled a hole through the higher part of a beam, joist ,bearer whatever your country calls it and drop a solid metal rod through the beam itself and hang it off that, even span two beams with a metal rod, buy it from a scrap yard thats never coming loose.

Or are you mounting a swivel device as well?
We've even wrapped 1/4 inch fenceing wire around the whole beam a few times and tied one into the bottom of the loops, fuk screws they are not going to cut it. Rope right around the beam even. Use a large U screw bolt to connect the chains to the rope or the chains to the wire. Going up through a beam vetrically I would car bog an expanding bolt into a hole, tighten as much as possible, you can even get them with large metal circles welded to the nut that opens the claws on the bolt.