I am in the process of building 2 new cross cut sleds. One has just one runner an will be to the right of the blade the other will be a full sled. The issue I have is I glued up 3 pieces of 3/4" plywood 4 inches tall for the back fence. I then routed a dado and installed a t track so I can use a stop block. When I mounted the first fence I went to test and noticed the wood rocked on the back fence. I grabbed my long straight edge and found out I have a small bow in both of the fences. Is there a way to fix the fence? Should I not use plywood for the fence and use something else. I thought once I have 3 piece of 3/4" laminated together I would have a nice straight and stable fence but now I have a bow. I did see a video where a guy used a section of angle iron to go the length of his fence to make sure it is straight. Any ideas?