Originally Posted by feline fanatic

Not only do you need special rulers, which are 1/4" thick, and a special foot, you need to make sure your machine has a ruler base. It is usually a plexiglass piece that snaps onto the neck of your machine head which gives you a rigid surface to place the ruler on. If you attempt to do ruler work without a ruler base you will not be able to hold the ruler flat for guiding the LA foot next to it. You also run the risk of damaging your LA or yourself.