What type of frame do you have? I have the Little Gracie II frame from the Grace Company. The frame comes with black plastic tracks that fit into a groove on both sides of the frame. The carriage wheels roll on these. Here is a picture, but I don't think you will be able to see it very well, because the groove & the steel rod are pretty much the same color. There is a site or blog called Quilting Tizzy (I think it's
www.quiltingtizzy.com) and they talk about doing this & there are a couple pictures. If you feel the picture is not clear enough let me know & I will take a couple more. Debbie