Every bit in this category is designed exclusively for use on Castle machines. The geometry of these bits creates clean, strong, and perfectly aligned pocket hole joints, with the specific angle of the cuts significantly reducing misalignment during assembly. Castle machine bits are widely used in cabinet making, bookcase construction, face frame assembly, and other joinery applications where joint strength and precision matter. These bits are not interchangeable with other machines or applications and must be matched to your specific Castle machine model.