Home Uncategorized This is timely and good to know! I just bought my first one today! :-) How to Sharpen Your Rotary Cutter Blade. Fold a piece of foil a few times and slice away with your dull rotary cutter, pausing a few times to test it out on your fabric scraps till it starts slicing away your fabric too! You will end up with a like-new rotary cutter!