| 摘要 |
Apparatus and methods are provided which are particularly useful in determining the location for producing aligned holes or hangers in consecuti ve support members such as joists from which pipe, conduit, wire, duct, and the like, will be supported, with the minimum amount of measuring or errors in measurements. The present invention includes an instrument that houses a sma ll diameter light beam projector, e.g., a laser light beam projector, that is provided with the ability to adjust the direction of beam projection from the instrument relative to its housing. The instrument is adapted to fit through a pre-bore d hole or a hanging support so as to direct the laser light beam into the desired direction to locate additional bored holes or hangers. The projected beam position is checked and if there is error, the projector is adjusted within the instrument housi ng to properly place the beam center at the desired location with respect to secon d joist. In the case of a through hole, the second hole is drilled and the beam passe s through the second hole to the third joist. The beam now accurately identifies the location for the third hole to be drilled and the procedure continues through the joists to the desired termination of the conduit.
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