A while back there was a guy that posted about needing a hole saw to install a lock in a steel door. I wonder how he made out.
There were a few suggestions that he use a bi-metal blade, and one poster said that any cheap hole saw should work well enough for a single lock installation job.
Well, I can attest to the fact that a cheap hole saw works just fine. I just installed a deadbolt in a steel clad door using a Harbor Freight carbon-steel hole saw set, 18 pieces for $9.99. That's what I call cheap! It seemed like the 2 1/8 saw cut though the steel easier than it cut through the foam core. Seriously.
I bought the kit last year just to have it on hand in case we needed it when I was helping my son install an exhaust fan. We never used it, but I figured for $10, why bother returning it? It'll probably come in handy some day. Well, tonight was the night. It cut a nice neat hole through the door although the mandrel bit was too short to reach all the way through the door. I just switched to a regular bit to punch through, then went back to the hole saw.
I don't know how many steel door locks the hole saw would work for, but it did just fine for the one lock I needed to install.