3D Drill Pattern Design · Dolmen

ISO nothing loaded —

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Burden m Across the face, row to row.

Spacing m Along the face, hole to hole.

Face bearing ° from N The direction the free face looks. Rows run at right angles to it.

Pattern A staggered pattern offsets alternate rows by half a spacing.

Standoff m No collar closer than this to the boundary.

Floor RL m Design grade. Overridden where a floor surface is loaded.

Dip ° from horizontal 90 is vertical. A rig reads dip from horizontal, and so does this.

Hole azimuth ° from N Which way the hole leans. Usually the face bearing.

Subdrill m Along the hole, below grade.

Diameter mm

Stemming m

Explosive density g/cc

Max hole length m A hole longer than this is refused rather than drawn.