Item # 6192
STEMALIGN Borehole Angle Device
Product description: This unit is a simple and inexpensive way to measure blast holes for better and safer blast results. With the use of a simple flashlight (included), the StemAlign can be used to measure the borehole inclination and also measure the borehole direction.
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Use of the Stemalign All measurements of the Stemalign are taken from a flashlight lowered into the borehole on a string or a tape measure. A baseline is set up using a string drawn tightly across the rims of the boreholes in a row. This would normally be parallel to the free face. | |
To Measure The Borehole Inclination (from the vertical) -
Hold the Stemalign vertically over the borehole with the level on the left side. -
Center the bubble and move so that you can see the light on the vertical cross-hair. -
Where the light intersects the vertical cross-hair is the inclination of the borehole. (The angle of the borehole from the vertical.) | |
| | To Measure the Borehole Direction -
Direction readings are taken relative to a baseline on the surface. This baseline would normally be a line between boreholes parallel to the free face. The direction readings are the angle (right or left) from the baseline. -
Holding the Stemalign telescope fashion, sight down the borehole directly at the flashlight. -
Rotate the Stemalign until the bubble level is at the bottom of the instrument and the bubble centered. -
Read the direction of the borehole by noting the image of the baseline in one of the sectors which are marked 0 to 30 degrees to the right or left. NOTE: The actual direction of the borehole is in line with the vertical cross-hair of the instrument. 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. If the collaring error is greater than a foot, a short straight edge should be placed parallel to the baseline across the top of the hole so that the direction can be read. |
