Whiteside Machine Flush Trim UpCut Spiral Bits These spiral bits offer state-of-the-art results in fl ush trimming. Our 1/4" diameter tools are great for small inside corners. Try our 1/8” diameter for extremely sharp corners. The 1/8” bit uses a solid pilot. All others feature a double ball bearing guide. Available in your choice of Up Cut, Down Cut, or an Up/Down Combination.