I have only made homemade peanut butter at work with commercial equipment, and still it took a long long time. I would be afraid that it would burn out home equipment before you could get it smooth. Maybe you could soak the nuts before processing? Don't know if it would work, but might be a fun experiment. Also the peanut butter I made went rancid very quickly.
Imp-loves peanut butter, but not peanut butter cookies