Problem: Have a frame made from 2.5 mm stainless steel sheet, with a small trough formed in it, 30 mm wide and 30 mm deep. At the bottom of this trough there are several holes 15 mm diameter. Need to make these holes 22 mm, but also offset them by 5 mm. Frame is fixed in place; work has to be done in situ, not in my workshop. - Can’t use a step bit as this wouldn’t move the centre by 5mm. - Difficult to use a hole saw as not easy to centre it given the hole is already 15mm wide - can’t clamp another piece of sheet metal underneath and drill a pilot hole into that, could drill some new holes through frame and bolt a strip of metal underneath to create new pilot hole in, but don’t really want two more holes for every hole I need to re-work. - Can’t use a Q-Max type punch as sheet material too thick. So currently thinking of using some kind of aggressive rotary file/reamer/de-burring bit to widen and re-position these holes. Could fit this into a cut-out tool (like a router, but set back from the workpiece so you can see what you are cutting into…). Can anyone recommend a particular bit? Can anyone suggest a better approach?