I'm in the process of fencing off potions of my backyard to form a child safe play area. A few lessons learned:

1) Post pounders are A LOT easier to use then sledge hammers. More so on those tall narrow "U" and T" posts. About 20 lbs seems to be the magic number for a manual pounder. Hearing protection required.

2) If you're planting more then a few posts, get a powered post driver. You'll still need a manual pounder for places you can't get a vehicle, but you won't kill youself planting 600-700 posts per mile.
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