I use fiberglass arrow shafts or 1/4 or 5/16 wood dowels for pushrods. In a 40 size plane you can use the 2/56 threaded rod. I tend to use 4/40 on the larger ones. Put a 90 degree bend in the end of the rod and put it through a hole in the dowel you drill.. Wrap it good with thread, not just once or twice, but wrap it good. I use either epoxy or Thick CA cover the entire threaded area. If I use Glass rods, I put the rod on the inside, with the 90 coming through a hole in the rod, grove a dowel that will fit inside the rod and hold the threaded rod in and glue it in well.