Abstract: A rotatable cutter may comprise a rotatable element, a stationary element, and a releasable interface. The releasable interface may be configured to substantially inhibit rotation of the rotatable element when the rotatable element and the stationary element are at least in partial contact. An earth-boring tool may include one or more rotatable elements.

Abstract: Rotatable elements for use with earth-boring tools include a movable element and a stationary element. The movable element and stationary element include an index positioning feature that is configured to rotate the movable element as the movable element moves between a first axial position and a second axial position.

Abstract: A cutting element assembly includes a rotatable cutting element, a sleeve having a cutter receiving aperture extending at least partially through the sleeve and configured to receive at least a portion of the rotatable cutting element within the cutter-receiving aperture, and a retention element rotatably coupling the rotatable cutting element to the sleeve. In some embodiments, the retention element includes a pin extending from a base portion of the sleeve and having at least one resilient portion having at least one protrusion radially extending outward. In additional embodiments, the retention element include a split ring or O-ring disposed within a groove of the rotatable cutting element. Earth-boring tools having rotating cutting elements are also disclosed.

Abstract: A cutting element assembly may include a support structure and a pin having a cylindrical exterior bearing surface. Retention elements may couple opposing ends of the pin to the support structure. The cutting element assembly also includes a rotatable cutting element including a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The rotatable cutting element may have an interior sidewall defining a longitudinally extending through hole. The pin may be positioned within the through hole of the rotatable cutting element and may be supported on the opposing ends thereof by the support structure. Methods include drilling a subterranean formation including engaging a formation with one or more of the rotatable cutting elements.

Abstract: A cutting element assembly includes a sleeve, a rotatable cutting element disposed within the sleeve, and a retention element. The sleeve and rotatable cutting element each have frustoconical surfaces. In some embodiments, a rotatable cutting element defines a first generally cylindrical surface, a second generally cylindrical surface, and an axial bearing surface opposite the end cutting surface and intersecting each of the first generally cylindrical surface and the second generally cylindrical surface. A bearing element may be disposed between an upper surface of a sleeve and a bearing surface of the rotatable cutting element. Earth-boring tools having rotating cutting elements are also disclosed.

Abstract: Rotatable cutting elements for earth-boring tools may include a substrate and a polycrystalline, superabrasive material secured to an end of the substrate. A sleeve may be sized and shaped to circumferentially surround at least a portion of the substrate. Rollers may be sized and shaped for positioning between, and making rolling contact with, the substrate and the sleeve, the rollers configured to rotate relative to the substrate and the sleeve and to enable the substrate to rotate relative to the sleeve. The rollers may be configured to bear at least radial forces acting on the substrate and the sleeve.

Abstract: An earth-boring tool comprising a bit-body, a blade, and a cutting element assembly. The cutting element assembly comprising a journal, a rotatable cutting element, and a retention element. The journal defines an upper cylindrical exterior surface, a first bearing surface that intersects the upper cylindrical exterior surface, and a first external groove in the upper cylindrical exterior surface. The rotatable cutting element comprises a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The substrate defines a second bearing surface, a longitudinally extending blind hole having a diameter larger than the diameter of the upper cylindrical exterior surface of the journal, and a second groove in the surface of the substrate defining the blind hole. The retention element is disposed at least partially in the first groove and partially within the second groove.

Abstract: A cutting element assembly may include a support structure and a pin having a cylindrical exterior bearing surface. Retention elements may couple opposing ends of the pin to the support structure. The cutting element assembly also includes a rotatable cutting element including a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The rotatable cutting element may have an interior sidewall defining a longitudinally extending through hole. The pin may be positioned within the through hole of the rotatable cutting element and may be supported on the opposing ends thereof by the support structure. Methods include drilling a subterranean formation including engaging a formation with one or more of the rotatable cutting elements.

Abstract: An earth-boring tool comprises a tool body and a cutting element assembly. The assembly comprises a cutting element including a table of polycrystalline hard material secured to a substrate. The table has a front cutting face and a central axis extending through a center of the front cutting face. The assembly also comprises a sleeve having a cavity formed therein and a central axis extending therethrough. A positioning feature and the cutting element may be disposed within the cavity. The positioning feature is configured to radially offset the central axis of the table from the central axis of the sleeve. The cutting element is rotatable about the central axis of the table within the cavity of the sleeve, and the cutting element and positioning feature are rotatable within the cavity of the sleeve such that the central axis of the table revolves about the central axis of the sleeve.

Abstract: An earth-boring tool includes a body and cutting elements rotatably mounted on the body. The earth-boring tool also includes a formation-engaging feature attached to the body and exposed at a face of the body. The formation-engaging feature may be configured to rotate about an axis of rotation responsive to frictional forces acting between the formation-engaging feature and a formation when the body moves relative to the formation. The axis of rotation of the formation-engaging feature may be oriented at an angle to an axis of rotation of the cutting elements. The formation-engaging feature may be operably coupled to the cutting elements such that rotation of the formation-engaging feature causes rotation of the cutting elements. Methods include drilling a subterranean formation including engaging a formation with the cutting elements and the formation-engaging features.

Abstract: An earth-boring tool is comprised of a body, blade, and cutting element assembly. The sleeve of the cutting element assembly has an interior surface that defines a cavity. A rotatable cutting element fits within the cavity secured by a threaded end cap. The rotatable cutting element is comprised of a polycrystalline hard material bonded to a supporting substrate. The polycrystalline hard material has an end cutting surface on a first end and the supporting substrate has a back surface on a second end opposite the first end. An annular ring has an upper surface in contact with the back surface of the supporting substrate and a lower surface in contact with the upper surface of the end cap. There is a spring in a void defined by an inner surface of the annular ring, the back surface of the supporting substrate, and the upper surface of the end cap.

Abstract: Rotatable cutting element assemblies includes a sleeve, a centering element positioned at least partially within the sleeve, a biasing element configured to apply a force against the centering element, and a rotatable cutting element coupled to the centering element and configured to rotate relative to the sleeve. Earth-boring tools include a tool body and at least one rotatable cutting element assembly coupled to the tool body. The at least one rotatable cutting element assembly includes a sleeve fixedly coupled to the tool body, a centering element positioned at least partially within the sleeve, a rotatable cutting element coupled to the centering element, and a biasing element configured to apply a force against the centering element. Methods of forming an earth-boring tool include positioning a centering element within a sleeve, fixedly coupling the sleeve to a tool body, and coupling a rotatable cutting element to the centering element.

Abstract: A cutting element assembly includes a sleeve, a rotatable cutting element disposed within the sleeve, and a retention element. The sleeve and rotatable cutting element each have frustoconical surfaces. In some embodiments, a rotatable cutting element defines a first generally cylindrical surface, a second generally cylindrical surface, and an axial bearing surface opposite the end cutting surface and intersecting each of the first generally cylindrical surface and the second generally cylindrical surface. A bearing element may be disposed between an upper surface of a sleeve and a bearing surface of the rotatable cutting element. Earth-boring tools having rotating cutting elements are also disclosed.

Abstract: A cutting element assembly includes a rotatable cutting element, a sleeve having a cutter receiving aperture extending at least partially through the sleeve and configured to receive at least a portion of the rotatable cutting element within the cutter-receiving aperture, and a retention element rotatably coupling the rotatable cutting element to the sleeve. In some embodiments, the retention element includes a pin extending from a base portion of the sleeve and having at least one resilient portion having at least one protrusion radially extending outward. In additional embodiments, the retention element include a split ring or O-ring disposed within a groove of the rotatable cutting element. Earth-boring tools having rotating cutting elements are also disclosed.

Abstract: A rotatable cutter may comprise a rotatable element, a stationary element, and a releasable interface. The releasable interface may be configured to substantially inhibit rotation of the rotatable element when the rotatable element and the stationary element are at least in partial contact. An earth-boring tool may include one or more rotatable elements.

Abstract: Earth-boring tools may include a body including blades projecting therefrom, an axis of rotation, and cutting elements secured to the blades. A profile of the cutting elements intersecting outermost points of cutting faces of the cutting elements as viewed projected rotationally onto a plane may be parabolic from immediately proximate the axis of rotation to a nose point at which a slope of the profile is such that an angle between the profile and a plane perpendicular to the axis of rotation is about 0°. In other embodiments, a first section of the profile may extend at a first slope, and a second section of the profile may extend at a second, different slope. In still other embodiments, a tangent line to the profile may be oriented at an angle of at least 15° at a location proximate to the axis of rotation.

Abstract: Rotatable elements for use with earth-boring tools include a movable element and a stationary element. The movable element and stationary element include an index positioning feature that is configured to rotate the movable element as the movable element moves between a first axial position and a second axial position.

Abstract: An earth-boring tool comprising a bit-body, a blade, and a cutting element assembly. The cutting element assembly comprising a journal, a rotatable cutting element, and a retention element. The journal defines an upper cylindrical exterior surface, a first bearing surface that intersects the upper cylindrical exterior surface, and a first external groove in the upper cylindrical exterior surface. The rotatable cutting element comprises a table of polycrystalline hard material having an end cutting surface and a supporting substrate. The substrate defines a second bearing surface, a longitudinally extending blind hole having a diameter larger than the diameter of the upper cylindrical exterior surface of the journal, and a second groove in the surface of the substrate defining the blind hole. The retention element is disposed at least partially in the first groove and partially within the second groove.

Abstract: Rotatable cutting elements for earth-boring tools may include a substrate and a polycrystalline, superabrasive material secured to an end of the substrate. A sleeve may be sized and shaped to circumferentially surround at least a portion of the substrate. Rollers may be sized and shaped for positioning between, and making rolling contact with, the substrate and the sleeve, the rollers configured to rotate relative to the substrate and the sleeve and to enable the substrate to rotate relative to the sleeve. The rollers may be configured to bear at least radial forces acting on the substrate and the sleeve.

Abstract: A cutter assembly, which may include a rotatable cutting element disposable within a pocket of an earth-boring tool, a sleeve configured to receive the rotatable cutting element, and at least one retention mechanism configured to secure the rotatable cutting element within the sleeve. The rotatable cutting element may include a substrate, a table, which may be comprised of a superhard, polycrystalline material disposed on a first end of the substrate, and a recess extending into a second, opposite end of the substrate. The sleeve may comprise at least one radial bearing surface, a backing support sized, shaped, and positioned to extend into the recess of the rotatable cutting element, and at least one axial thrust-bearing surface located on the backing support and positioned to contact the substrate within the recess.