Customized version of http://www.thingiverse.com/thing:193647

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=193647

Using the following options:

head_diameter = 12
type = washer
texture = exclude
thread_outer_diameter = 8
nut_type = normal
resolution = 0.5
thread_step = 2
facets = 6
slot_width = 1
countersink = 2
slot_depth = 2
nut_thread_outer_diameter = 9
wing_ratio = 1
nut_diameter = 12
head_height = 5
drive_type = socket
thickness = 2.25
thread_length = 25
nut_resolution = 0.5
head_type = hex
inner_diameter = 8.3
nut_thread_step = 2
nut_step_shape_degrees = 45
step_shape_degrees = 45
non_thread_diameter = 0
non_thread_length = 0
nut_height = 6
outer_diameter = 14
drive_diameter = 5