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.
</table
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.
|
