RMA wrote:Matching machined tapers hold the bit it place. Similar to the Morse taper that hold most drill chucks in place
on a drill press.
whistlenut wrote:Actually the vibration helps hold then in place, too. Normally, there is a centering pilot bit that may be held in by a taper or a simple rubber o-ring, as Hilti does. Either way, they work great, last a long time and will be in your tool box for years.
Don't worry about them falling apart as you are coring, just keep enough water on the operation. By the way, Hitachi does a terrific job with there concrete hammers, drills, breakers. etc. Fair prices, very durable tools. Enjoy!