Abstract: A hybrid bit includes fixed blades and wheel support structures. The wheel support structure includes a wheel inserted into a slot between a leading support and a trailing support. One or more shims fill a gap between a flange and the leading supports. An elongated seal between the wheel and the supports is provided to seal the wheel support.

Abstract: This invention provides an improved cutting element for downhole cutting tools including a support element and a beveled shearing element disposed on the support element and a drill bit including the cutting element; a cutting element including a support element and a shearing element disposed on the support element, wherein the shearing element includes TSP, a sharpened cutting edge, and at least one blended edge that forms part of an interface with the support element and a drill bit including the cutting element. Cutting inserts including an insert body and the shearing elements disclosed above are provided. Also provided are methods for forming the cutting elements and drill bit inserts and a method for drilling mixed earth formations using the improved downhole cutting tools of the present invention.