blender screw 2

add a vertex, add screw modifier, e + z to extrude vertex

increase iterations, and screw height in screw modifier

select the beginning 2 vertices, ctrl + r to loop cut

select middle vertex, g + y to move 

ctrl + r to loop cut between middle and top, middle and bottom vertex

select new vertex, g + y to move. select top vertex, g + z to close gap between threads.

add weld modifier. apply screw and weld modifier

shift + select all vertices from bottom to top

F3 -> merge at end

alt + select bottom edges, e to extrude, bisect to cut the bottom

alt + select bottom edges, e to extrude, s to scale down

select first 3 vertices on thread, g + g to move in

add a cylinder on top, add Boolean modifier for Philips cut 

reference:

https://www.youtube.com/watch?v=IIvSJYdcHn8