Yes, this will work on thicker grinds no problem. I used to straighten 4 inch diameter shafts using a similar method, but a MUCH bigger torch! BTW, the vise is unnecessary - you only need it to hold the steel. The heating and cooling does all the work. This is basically yielding the steel a tiny bit, which gives it a teensy bend. When the torch heats the steel it wants to expand but is held in place by the colder steel surrounding it, so it yields a smidge where it's weakest and when it's cooled it pulls back a tiny bit farther than it stretched.