I second the wrist thing. I had to cut six 2" holes in an 1/8" plate for my new LED lights and managed to bend the pilot bit while wrenching my hand nicely. The problem was the pilot bit breaking through and the saw bit suddenly catching, as another user here mentioned. Definitely better to drill the pilot hole separately.
If wanting a square hole by using a sabre or sawzall drill an appropriate size hole per blade size at each corner to help starting and turning, use coolant and/or a slow speed, heat kills saw blades. A circular saw with carbide teeth or a plain steel blade reversed (friction saw) will do the job nicely also, ear protection is mandatory, noise is unbelievable.
If wanting a square hole by using a sabre or sawzall drill an appropriate size hole per blade size at each corner to help starting and turning, use coolant and/or a slow speed, heat kills saw blades. A circular saw with carbide teeth or a plain steel blade reversed (friction saw) will do the job nicely also, ear protection is mandatory, noise is unbelievable.
Square holes I use a cut off wheel on an angle grinder and finish with jig saw or sawzall.
been there done that?once? for over twenty years now?
you will kill a cordless with anything over 1 inch.
a 1/2 inch drill is definitely the one to use.
the handle screws into the drill on either side and on some brands the top.
put the handle in the side of the drill where you can let the framing or wall hold the handle for when the hole saw grabs/not an if and put your free hand work the drill.
when the hole saw breaks through the metal regardless of thickness it will start binding because it is finding purchase/resistance in one spot because that is where your hands pressure was or you were leaning in out or whatever but when it starts grabbing you just start rocking it around the opening you are cutting and if it wants to hang up towards the end the you put the drill in reverse and finish the cut.
alot of the older 1/2 inch drills didnt have a reverse so check your.
for 26/20 guage metal a standard skill saw with the blade turned backwards will make good square cuts.
for hole saws for steel i have had the most longevity out of carbide tipped bits and working in commercial construction i love the milwaukee stuff that aint cheap but i dont pay for it.
Lennox gold is good .
have fun
3/4" plate is a different beast from the 12 gauge channel that makes up a bus floor. A bi-metal hole saw should be sufficient. Using fire on galvanized metal is going to make a toxic cloud I wouldn't want to see inside a bus, personally.
If I am not the one operating the angle grinder it can cut some very precise holes.
I had a gent, Brian, helping me with the sheet metal on the back of my bus. We needed to cut the "bulkhead" in the back from 12 gauge steel. We already had the break on the bottom of the piece so the curved top needed to be spot on.
I was freeking amazed when we set the piece in place. It looked like it was laser cut to fit.
The tool is important but the skill of the operator is the key.