</font><font color="blue" class="small">( </font><font color="blueclass=small">( Is it easier and better to drill a hole for a fence post with a 9 inch or a 12 inch? )</font>
I suspect the following information would help in getting an answer from some of the fence builders on the forum.
What type of fence post, length, diameter, and how deep will they be in the ground?
What type of soil?
Are you going to tamp the posts in or pour concrete around them?
What type of fence material?
How far apart are the posts going to be?
Inquiring minds want to know.
Bill Tolle )</font>
In GA red clay I have been using 4" round posts for the main run, 6" round for the corners, and I space them 8' apart for wood fence & 10' apart for field fence. Most of my field fence is done with steel posts driven by hand drivers. On all the wood corner posts and brace posts I kick in a little soil and tamp it in with HD steel tamp rod at the bottom then add more soil and fill with concrete at the top, fast dry type that doesn't require mixing. Just pour in dry and add water. I still mix it a little right in the hole with my tamp rod and once it sets up(2 hours) you can hang the wire & gates same day.
It's been holding up really well.
Last week I had a very large white pine fall and landed on a corner post section and go right though a metal gate. The gate was smashed all the way to the ground and where it hit the corner post horizontal support it snapped the 4" PT brace. All vertical posts were fine. Not loose, no damage. I just hung a new gate and replaced the vertical support and spliced in a short pc of new wire. Those new wire crimp splice kits are the way to go, no twisting wire. Field fence has 10 horz. wires and 10 crimps is so much easier and cleaner than 10 twisted wire splices.
Good luck with your fence.