Dig around the stake to center the hole. Unless you have very soft soil, you'll work way too hard digging with just a clamshell digger. Loosen the soil and carve away at the sides with the tile spade.

Among the first post-hole-digger-haters were the old dyed-in-the-wool cowboys who believed any work not carried out on the back of a horse was a sin, an embarrassment and beneath their dignity.