You should also double-check the length of your all-thread rods. I'd dummy one up and try it out before cutting all of them. It needs to be just long enough to catch a couple of threads and snug down without punching out through the cap nut. The actual "cap" portion of cap nuts is fairly thin, and if the all-thread is even a bit too long it will punch through the end when you snug it up.
To minimize potential cupping, we decided to make the top by gluing two pieces of 1×6 together rather than using a solid board. Choose a straight piece of 1×6 with a sharp, clean edge. Cut the pieces long and trim the top to length after you glue the two parts together. For pro tips on gluing boards edge-to-edge, see “Edge Gluing Boards” . Justin and Jackson cut biscuit slots in the sides of the two 1x6s to help hold them in alignment while installing the clamps. Glue and clamp the two 1x6s. Then let the glue set up about 30 minutes before routing the edge (Photo 10).
Thickness planer. A thickness planer is used to fix surfaces of imperfect wood. If you are picking up less than perfect wood from the lumberyard, wood with some surface defects, a planer will let you fix that wood in the quickest time. A thickness planer pays for itself quick as it allows you to buy cheaper wood that doesn’t have perfect surfaces and fix it yourself. Be careful though. You loose wood during planing. So the remaining amount of wood still has to be worth the price you paid for it.