I work as an aide at a middle school. We have a large blade manual paper cutter (not sure of brand). The blade is very dull. I have looked on line and have seen replacement blades for sale. I have sharpened scissors by cutting up some sandpaper. It seemed to work fine. My question - could I place a sheet of sandpaper on the paper cutter and make several cuts - would this sharpen or dull the large cutter blade? Schools are on tight budgets and I thought this might be a less expensive way than to buy a new blade? Any other suggestions? Thank you.