If you are building a lawn swing of any type you will need a structure that will be able to handle the back and forth motion without shifting, tipping, or becoming unsafe in any way.
This is an ideal lawn swing support for the lawn or porch swing plan that we featured in the past.
This is a simple plan that uses 4″ x 4″ posts along with some large bolts and flat steel. All of the material is available from your local Home Depot or Lowe’s and you should be able to build this structure in a few hours.
Full swing support woodworking plan
Good luck and swing safely.