Stemlock Stemalign™ is an optical device that provides quick and precise measured angles and direction of blast holes.
Stemalign uses a powerful LED light to obtain the exact angle and direction. To use, start by lowering a flashlight tied to a string, or measuring tape, into the borehole. Next, set up a baseline by tightly drawing a string across the rims of a row of boreholes. Normally this baseline is parallel to the free face.
Borehole Inclination / Angle
Inclination readings are the angle from the vertical. To measure inclination:
- Hold Stemalign vertically over the borehole, with the level on the left side
- Center the bubble and move so that you can see the beam of light on the vertical cross hair
- Where the beam of light intersects the vertical cross hair is the inclination of the borehole
Direction readings are taken relative to the baseline set. The direction readings are the angle (right or left) from the baseline. To measure direction:
- Hold Stemalign telescope fashion, and sight down the borehole at the flashlight
- Rotate Stemalign until the bubble level is at the bottom of the display, and the bubble is centered.
- Find the string on one of the sectors which are marked 0 to 30 degrees located on the right or left of the viewing area
The actual direction of the borehole is aligned with the vertical cross hair on the display. The image of the baseline shows the angle of deviation of the hole. If the borehole was drilled correctly, the vertical cross hair would be perpendicular to the baseline.