| 摘要 |
An improved self centering guide pipe axis laser guide is based on the use of three parallel links spaced 120 degrees apart which are engaged to be expanded or contracted. When expanded the links contact the inside diameter of the pipe which accordingly establishes the center axis of the pipe. The links are actuated for expansion or contraction by mounting a spring base spider element in association with a spider lever element on a smooth pipe housing, wherein the movement of the spring base spider element and the spider lever element is controlled by thumbscrews on each of the elements, the smooth pipe housing containing within, the power supply and laser module, and a removable switch assembly at the rear enabling easy access to the batteries. The laser guide can readily be withdrawn from the pipe by attaching a tether line to the front end and levels for determining the slope are mounted in slots in both the front and rear spider elements. The axis laser guide can also be cradled on top of the pipe for making alignment measurements when access to the interior of the pipe is obstructed.
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