Upcut bits are the go to choice where having a clean bottom surface or getting maximum chip evacuation is most important. The up cut action of the bit pulls the chips up and out of the cut allowing for maximum chip evacuation. Because the chips are being pulled up this will result in a clean bottom edge of the cut

These Mortise heads are designed to screw down onto a Helix Mortise Arbor for easy transition from one cutting head to the next.