How to Set Fence Posts in a Straight Line Part #4 Step 7 Align Posts with the String or Laser Center each post hole on the stake when digging it. Leave the string in position, and set each post so that its outside edge just touches the string when it's level. Alternatively, use a laser to double-check alignment when you're setting the posts. The laser should graze the outside edge of each post, meaning when the post is slightly tilted to the outside, it intercepts the beam. http://www.eurofence-