I've been through drilling 8" plugs by hand with a 12" bit. Naturally I start the first few inches of each end on the lathe.
I had a lot of misses till I went out and bought new drill bits. Now dead center every time. Oh I also lube 12" shaft with WD40.
I use 1/8" bits and back up several times to remove shavings.
Can't put alot of pressure on long bit or it will bend.
I found if I take my time they come out perfect.
