Hello I'm finishing up my Grandfather clocks project. I have a question about wood movement and grain. I used 18" wide Curly Maple boards for the base. The grain is running horizontal. I'm making the back in 2 pieces. The bottom is running horizontal like the other 3 sides of the base. I did this thinking they would move in the same direction and hopefully not crack. Should I screw, nail or glue the back on?