You need to take your wood back and get pieces with the exact dimensions you need. Trying to "make it work" with wood is a sure recipe for frustration and eventual failure. I've built many many racks and can tell you from personal experience that you'll be happier in the long run if you don't have to mickey mouse stuff together. It may be a bit of a pain in the butt to keep going back, but when you have a perfect rack that functions properly you'll be glad you did. Take your tape measure with you and measure each piece as it's cut. If the guy doing the cutting can't use the saw properly, ask for someone else to do the cutting.