I need to dig a 12 inch diameter hole for some 4x4 fence posts that I'm digging but I only have access to an 8-inch power auger. My experience drilling holes in wood tells me that if I try to drill a hole next to an existing hole my bit will slip and go all over the place in an unsafe way. My question here is if I only have access to an 8-inch auger whats my safest bet at getting a 12 inch wide hole?
What I was thinking was to go slow and dig three holes where the center of each hole is 4 inches apart from each other until I get to the depth that I need. Something like a venn diagram with 3 circles. Working my way down into the ground maybe 6 inches at a time. This sounds pretty tedious since I have many holes to dig so Anyone have any better ideas?
My question stems from this video: https://youtu.be/aQ24ykIBVOM?t=2m54s