The pilot bit — also called a drill head or steering head — is the first piece of tooling that enters the ground. It creates the pilot bore that the reamer will later enlarge. Choosing the right pilot bit for your soil conditions is critical: the wrong bit can cause steering problems, excessive wear, or a stuck drill string. This guide covers the most common pilot bit types used with Vermeer and Ditch Witch rigs.

How a Pilot Bit Works

The pilot bit is mounted to the front of the transmitter housing (also called the sonde housing). It steers the drill string by using the angled face (called the steer face) to redirect the bore path when the drill string is pushed without rotation. When the drill string rotates, the bit drills straight ahead. This combination of push-without-rotation and rotation-while-pushing is what allows the operator to steer the bore.

Transmitter Housings: The Foundation of Your Drill Head

Before selecting a bit, you need the right housing. The housing holds the locating transmitter (sonde) and connects the drill string to the bit. Melfred Borzall’s SD Housing is one of the most popular in the industry, featuring:

• FastBack® Ready — allows direct pullback without removing the drill head
• Dual SuperNozzles — for maximum fluid delivery to the bit face
• Pit Bull™ Pins — machined dowel pins that secure the blade to the steer face, reducing the risk of losing a blade downhole
• Tri-Con™ Ready — compatible with Melfred Borzall’s newest threadless connection system
• Compatible with Subsite®, DigiTrak™, and Underground Magnetics™ transmitters

Melfred Borzall Universal SD Housings are available in three sizes for different rig classes:

Rig Thrust Class	Housing Diameter	Rear Thread	Front Thread
25,000 – 40,000 lbs	3.5″	2.375″ IF	2.375″ Reg
50,000 – 80,000 lbs	4.25″	2.875″ IF	2.875″ Reg
80,000 – 150,000 lbs	4.75″	3.5″ IF	3.5″ Reg

Pilot Bit Types by Ground Condition

1. Eagle Claw® Bits — Sand, Clay, and Mixed Soil

The Eagle Claw is Melfred Borzall’s most popular pilot bit for soft to medium ground conditions. It features aggressive carbide teeth on the steer face and a swept-back blade design that provides excellent steering response. Available in 3.5″, 4.25″, and 5″ cut diameters. Compatible with Vermeer 5-bolt, Vermeer 6-bolt, and Ditch Witch 5-bolt and 6-bolt housing patterns.

2. Iron Fist® Bits — Cobble, Gravel, and Hard Ground

The Iron Fist is designed for harder ground conditions including cobble, gravel, and hard clay. It uses carbide inserts (similar to tricone bit technology) on the steer face for maximum penetration in abrasive soils. Available in 4.25″ and 5″ cut diameters with Tri-Con™ connection option.

3. Directional Blades — Soft Soil and Clay

Bolt-on directional blades are used in soft, uniform soil conditions such as sandy loam and soft clay. They provide fast penetration rates and are easy to replace in the field. The blade bolts directly to the housing steer face using the Pit Bull™ pin system to prevent loss downhole.

4. The Tri-Con™ System — Faster Bit Changes

Melfred Borzall’s newest innovation is the Tri-Con™ System — a patent-pending threadless connection that uses a rounded triangular shape to transfer rotary torque without the stress concentrations of splined connections. Benefits include:

• Faster bit swaps — no breakout wrench needed
• Ability to ream and pullback directly from the transmitter housing
• Standard API connection for quick-connect systems
• Eliminates the need for starter rods and adapters in some applications
• Designed for up to 30,000-pound class rigs

Quick Reference: Bit Selection by Ground Condition

Ground Condition	Recommended Bit	Notes
Soft clay / sandy loam	Directional blade	Fast penetration, easy field replacement
Medium clay / mixed soil	Eagle Claw®	Best all-around bit for most conditions
Sand / loose gravel	Eagle Claw® or Iron Fist®	Iron Fist for abrasive sand
Cobble / hard clay	Iron Fist®	Carbide inserts for hard ground
Rock	Dual rock drill head (Vermeer) or AT system (Ditch Witch)	Requires specialized rig and tooling