Grinder! Good idea!
Discussion
It’s about the simplest option to cut that 1/8” steel plate. I been tempted to get that Bauer 5 3/8” metal circular saw and almost bought it for this but managed to hold on to my money lol
I recommend a heavy duty 120V 7" grinder with a cutting wheel if the 4" grinder won't cut it.
This one will do 5” wheels, and has covered everything I’ve needed so far. We did have a parking lot job once where we had to modify the handicap ramps, which were concrete. Boss man went and got a big 7” corded with a 7” diamond cup wheel for that one. That thing would wear you out lol
I had to cut through 1/2" steel sandwiched with 1/2x cast aluminum. It was a mess, took about 20 straight hours.