Subdrilling to optimal levels!


Subdrilling is the process of drilling below the desired floor in blasting in order to form a smooth floor at correct level. If your subdrill is not low enough the floor may be uneven, or leave a large toe. If your subdrill is to large then you lose valuable time and money with extra drilling and extra loading. Here at Academy Blasting we believe in optimizing your blast design to achieve the best results for the lowest price!


If you look at the picture above you can see that subdrill causes tension in the bottom of a hole. When the subdrill is to short this area of maximum tension will be located higher up, and not break to the bottom of the floor. In order to break a smooth, correct floor we must find the perfect subdrill depth. This can be done by using a ratio of the burden.

Subdrill Equation

Subdrill (feet) = 0.3 x Burden (feet)

Subdrill (meters) = 0.3 x Burden (meters)

This short video by Anthony Konya will demonstrate how to quickly calculate a subdrill to try on your next blast.

Academy Blasting

Here at Academy Blasting we bring the science of blasting down to a practical level that is easy to understand and implement on your site. These implementation have been shown to reduce vibration levels, increase fragmentation, and save companies thousands of dollars per blast! We do this by guiding students and professionals through the world of blasting through our proven step by step methods. We will have your blasts looking and feeling great in no time

Are you interested in learning more about Academy Blasting? Just fill out the form on the Support page and let us know what your interested in!