Abstract: A collet adapter includes a spindle adapter body configured to removably mount to a non-collet-ready spindle of a machine (e.g., a lathe or machining center). The spindle adapter body has a collet seat configured to mate with a collet. The adapter also includes an adapter collar configured to removably mount to the spindle adapter. When the collar is mounted to the adapter body, it facilitates secure attachment of a device with a spindle mount to the machine via an enlarged mounting shoulder of the collar. The collar can be removed to provide improved radial access to a work piece being held by the spindle adapter body and a non-step collet.