Diamond Drillers: Understanding the Importance of Bit Weight

As a diamond driller, you're likely no stranger to the importance of choosing the right equipment for your project. One crucial aspect that can make or break your drilling success is bit weight. In this column, we'll delve into the world of diamond drillers and explore the key factors that affect bit weight.

When it comes to cutting metal, carbide inserts are a common sight in machine shops. Similarly, when working with rock formations, PDC bits have become increasingly popular due to their ability to withstand pressures up to 25 kilopounds per square inch (KSI). Tricones, on the other hand, work by crushing the rock through tooth or button force.

However, achieving optimal performance from these bits requires a significant amount of weight. For instance, when using a 12¼-inch button tricone bit in medium-hard formations, you may need to apply up to 36,000 to 72,000 pounds of bit weight for it to function as designed. TCI button bits can require even more, with some reaching weights of 6,000 pounds per bit inch.

Tooth bits, on the other hand, typically require less weight, ranging from 1,000 to 4,000 pounds per inch of bit diameter. Tricone bits, however, are a different story altogether, as their recommended weight can vary greatly depending on size and formation type.

This is where diamond drillers with DTH hammers gain an advantage. Unlike traditional tricone bits, which rely on crushing the rock through tooth or button force, hammer bits cut by pulverizing the rock through strikes of the piston against the top of the hammer bit. This approach eliminates the need for excessive weight, making it ideal for certain formations.

For example, a 6-inch hammer bit would typically require only 3,000 pounds of bit weight. In some cases, you may even see total bit weights ranging from 6,500 to 7,700 pounds, with some operators using a 'rule of thumb' of 500 pounds per inch of bit diameter.

In one notable instance, Todd Taylor with Infinity Tool Mfg shared his experiences working on 12¼-inch holes that were over 1,100 feet deep. He was using a tricone bit and 15-foot stabilizer in conjunction with 4½-inch drill pipe. When asked about the hole size, depth, and drill string makeup, he emphasized the importance of choosing the right equipment for each specific project.

By understanding the intricacies of bit weight, diamond drillers can ensure they're selecting the optimal tools for their project's unique needs. Whether you're working with PDC bits, tricone bits, or DTH hammer bits, a solid grasp of bit weight will help you achieve your drilling goals with greater ease and efficiency.

Diamond drillers