What final thickness is best for sinker redwood?
Often redwood can be left a little thicker than spruce, depending on its stiffness. With our 16 1/4 wide steel string guitars, we have made them as thick as 3mm or .118-.120 inch thick in the past with smaller bodied guitars being a few thousands thinner. The one I am working on now is quite stiff and so I took it down to .105 inch. The best way to decide on the proper thickness is to deflection test each top either by hand or the way we do it is to place a 16 inch long, 6 pound weight in the middle of the joined top that is suspended between two up-side-down aluminum angles the length of the guitar body apart and measure the deflection. Then you can thickness sand until you reach a certain point of deflection with a dial indicator. There is quite a range of stiffness within a certain species of trees and even within the same tree! If you measure each top and record the data, you will be able to determine the optimum thickness for each top, regardless of the species based on deflection
