Degreasing starts with removing loose goo, and for that I like
to scrape with wood wedges. Then you can use any solvent you like,
like oil or kerosene on a rag, and get off any non-polymerized
greasy residues. A brush (parts cleaning brush from
auto store) helps, too. The gunky stuff, like boiled linseed oil,
comes off with paint remover or TSP. Or maybe steam
cleaning, if you can get the equipment.
I like to do a final wipe with waterless hand cleaner, myself,
because it's bio-friendly, and washes up with water.
Goo Gone, turpentine, and Formula 409 have their place.
For real clean, though, like for a plating shop, there are
ultrasonic cleaners and low-residue things like
methylene chloride in Freon (used to be 'Freon TMC')
that you can try.
Mostly, though, machine tools get re-greased more often