I need some help in correcting a problem with a finished opening for a bifold door. The top of the door fits fine but the bottom of the door needs about 3/4" cut off. I want to use a table saw to cut this angle but I'm not quite sure how to do it. Basically I want my door to be 30" at the top and 29.25" at the bottom, with a smooth transition in between. I am certainly no expert with the table saw...probably considered a nivice still, so the simplest explanation would be great. Thanks.