The topic of lock systems comes up a lot. I had a cheap old Master combination lock on the bag that I use to hold my gym stuff. I have long since forgotten the combination so I thought I'd just cut it off.

First I tried my hack saw on the hasp. The hardened hasp laughed at my hack saw.
Then I beat on the body of the lock with my hammer. I seriously mis-shaped the body but the lock still wouldn't open.
I tried cutting the body of the lock with my hack saw. That worked, but it still wouldn't open.
I used a pry bar in the saw cut kerf to pry the body of the lock apart. I could clearly see the insides, but it still wouldn't open.
Finally I used my channel lock pliers to pull the innards out one at a time. Success.

I don't have a big bolt cutter or an angle grinder and I thought my Dremel would take too long. I'm laughing at movies, like Rocky, where he hits the padlock with a fire extinguisher and it pops right open.

I guess that it's good that I'm honest because I'd suck at being a thief.

That is a good account of the removal, thanks for sharing.

Those locks keep honest people honest.

This inexpensive bolt cutter is a quick / easy / quiet way to open that lock.

The DeWalt 4½" Right Angle Grinder that I have in my tool set would cut through that very quickly. It is loud w/ lots of sparks. They have a battery-powered version for those who like cordless tools. I have used this tool for many projects and it never disappoints. I have the myriad of wheels for different materials and operations for maximum versatility, for steel, stainless, aluminum and masonry.

I've done that same thing with my old master lock combination. Pretty much the same process and amazed how little left seemed to hold so securely.

I recently acquired a used bike that had a U-Lock attached to the frame. I started with a hacksaw, which would have taken an hour. I decided to try my Dremel with some metal cutting wheels. Two wheels and about 25 minutes later it was off (with a little help from the hacksaw). It was a pain getting that thing cut. I'm sure if I had a larger angle grinder if may have been quicker, but I have to say my hat was off to the manufacturer on how solid it was forged.

Diamond cutting disc in the Dremel - 2 minutes.

Tile cutting blade in hacksaw frame - 20-30 minutes.

Those old Master gym locker locks ... faster and easier to pick them.

It just takes patience ... and I figure anyone who wants to steal my bike isn't serious, and probably lacks the patience.

It the thief was serious, s/he'd have the tools ... and would risk a bust stealing my beat old commuter bike.