I was asked to do a bowl coring demo at Galloway Woodturners. I have made a pdf file of the presentation so that it can be downloaded.
If you want to see more about coring then these links will get you to some of the turners mentioned in the presentation:
Brendan Stemp - bowlsaver max 3
Reed Gray (robohippy) - McNaughton
For a very thorough overview of coring and coring systems then this link to an AAW (you don't have to be American to join!) article is well worth a read:
If you have the urge to splurge some cash then these are the dealers in the UK:
McNaughton - Toolpost
Woodcut - Axminster