Boart Longyear

Where straight hole accuracy is required in hard, abrasive ground, blade bits are ideal, as they tend to resist gauge wear better than button bits. Generally, blade bits are not as productive and yield higher drilling costs than button bits. In addition, blade bits generally require more frequent sharpening than button bits because of the less wear resistant carbide grades on the face.

Cross Bits

- Easier to sharpen than X-bits, inset angles are equal on all four sides
- Bits 64mm and less are easier to sharpen than button bits of the same size
- In certain rock conditions, cross bits tend to produce a spiraled five sided hole (especially in diameters larger than 64mm)

"X" Bits

- X-bits tend to drill round holes in all rock conditions
- The steel support in the narrow parts of the X becomes inadequate in X-bits smaller than 64 mm because of the restricted circumference.