Raise Bore pilot holes Civil Construction


Raise Bore pilot holes

Raise bore drilling is a specialized drilling application for creating a vertical or horizontal, circular excavation between two levels. It is most commonly utilized for the development of shafts from the surface to underground.

The Raise bore process begins with drilling a pilot hole (small diameter drill hole) from base level to the target level. Once the pilot hole is achieved to plan, the raise bore machine mechanically reams from the lower level to either the surface or another underground level, utilising a large diameter reamer and excavating the hole to the desired width. 

Raise Bore pilot holes Civil Construction


Factoring in the geological structure of the drill site and the proximity of existing infrastructure, the consequences of missing the target can be disastrous. So a high level of strict planning goes into all raise boring programs, with an extremely low tolerance for error. Therefore, due to the fact that every drill hole deviates, the key challenge with raise boring is drilling the pilot hole on target.

In addition, raise boring rigs are compact in height, the pilot holes are often vertical, and always drilled with short rods that have variable inner diameters. These factors all pose as further challenges when conducting downhole navigational surveys to measure the deviation.


Conducting precise downhole navigation surveys is essential for periodically monitoring the deviation of the pilot hole to ensure that it is on target, and additionally to verify the pilot holes definitive position once it is completed. 

The solution is utilizing downhole navigation survey equipment that is compatible with raise boring rig sizes and rod types, which is the DeviGyro RG40 Standard. With innovative, variable running gear configurations and centralizer options, raise boring operators have the functionality they need to conduct high accuracy, efficient surveys. 


  • Quick set up time 
  • User-friendly, intuitive operating software   
  • High speed, continuous surveying (up to 100m/min)   
  • Adjustable and adaptable centralizer options to fit a variety of diameters and shapes 
  • Seamless data transfer between site and office 
  • Repeatable precision at any angle 
  • Not affected by magnetics 

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Frequently asked questions

How long is the DeviGyro RG40 Standard when fully assembled?

Compact (without extension bars) 1.5m. Extended (with extension bars) 2.2m.

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Is the DeviGyro RG40 Standard North Seeking?

No, the DeviGyro is not north seeking. It is a high precision, continuous rate gyro using north seeking principles and proprietary algorithms to determine the drill hole path from a known direction. Most continuous north seeking gyros operate in the same way. They determine a start direction and then measure the “rate“ of change from the initial reference.

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