Maybe this will help.
[image: Screenshot - 6_22_2016 , 6_24_26 PM.png]
A circle with a radius of the ring.
[image: Screenshot - 6_22_2016 , 6_24_58 PM.png]
Extrude with Push/Pull to the required thickness.
[image: Screenshot - 6_22_2016 , 6_26_44 PM.png]
Use Offset first to delineate the radius of the post. Then draw a line for the flat.
[image: Screenshot - 6_22_2016 , 6_27_32 PM.png]
Push/Pull to get rid of the waste.
[image: Screenshot - 6_22_2016 , 6_27_56 PM.png]
Select the remainder of the offset edge and use Move/Copy to copy it to the opposite side. You could have used Offset on the other side as before but this is quick and easy, too.
[image: Screenshot - 6_22_2016 , 6_28_24 PM.png]
Push/Pull the inner faces on both sides to make the post.