When you start grinding cranks, one of the tools you should place where you can grab it quickly is a GOOD flashlight. And if you are anywhere near as old as I am, get a eye doctor's prescription for a pair of glasses that have the correct focal length for the distance between where your eye is (while standing in front of the Storm), and where the stone is touching the crank. You have to use the flashlight (and good glasses) to see how close the side of the stone is to the side of the crank to avoid banging into the cheek (or whatever) and causing the stone to "ring". If you experience a crash like this, you will most likely have to go to the next undersize to fix the mess.
Another lesson that you probably have no concept about, is to believe the Arnold gauge, and to continue grinding to the Arnold gauge's zero mark, without stopping and miking at a thou or so before your finished size. I can see a person wanting to double check before final size, but that is a mistake in this case. The Arnold gauge accumulates a film of sludge on the indicator's surfaces, and will give a slightly undersize journal, but will repeat time after time, If you stop to check before final size, you disturb the sludge, and it "game over" for the Arnold gauge giving a good accurate reading. Do remember to grind about .0003" large, because that is about how much sludge will be under the Arnold gauge thimbles. Otherwise, when you get through grinding to the Arnold gauge's zero, and when you wipe the finished journal off to mike it, you will be undersize by about .0003"
You should be getting the feeling by now, that crank grinding is an art and not a science, at least for us guys that do not have the super deluxe grinders. We can still produce good work though, so go for it.
As a credential, our shop's raggy old Storm and Van Norman grinders, did the crank for our own fuel dragster, which went out and became the World's fastest Chevy powered dragster in 1961-2-3, some where in there, I can't remember exactly when, but it was a 327" small block, stroked 1/4" and running 40% nitromethane and a stock GMC 671 blower, First Chevy to go 180 MPH in the quarter mile. We were famous for two weeks before someone else went faster. My, isn't fame fleeting?