tag:blogger.com,1999:blog-251143672011-04-21T21:30:50.936-07:00Chris Gonserhttp://www.blogger.com/profile/07042775573468818639noreply@blogger.comBlogger11100tag:blogger.com,1999:blog-25114367.post-1143793285833322532006-03-31T00:20:00.000-08:002006-03-31T00:21:25.836-08:00Is it straight?<br /><br />... What is the straightest reference line created by an optical tooling instrument? The line of sight! Each optical tooling instrument is specially crafted to maintain a straight line of sight within extremely close tolerances. To measure the alignment of several points that are supposed to be on a straight line over a distance, the line of sight itself is used as a reference line. This invisible line is straight as an arrow, has no weight, cannot sag, become fouled, or be disturbed. It constitutes a precise, unvarying reference, determining straightness to within thousandths of an inch.<br /><br />Is it level?<br /><br />. . . If you need to level equipment that is only a few feet long to tolerances of 0.001" to 0.003", it may not be a big deal – but what if that equipment is 25’ or 50’ long and equally wide, or has components at different elevations which all need to be level? Then what? Optical alignment methods overcome the disadvantages of other methods and assure an object is level to within a few thousandths of an inch, even when the area in question is large. This is accomplished by sweeping a level line of sight back and forth which creates a precise horizontal reference plane. This plane can also be used to determine if something is flat – and although we sometimes use the terms interchangeably, "flat" is definitely different than "level".<br /><br />Is it plumb?<br /><br />... This is similar to the question "Is it level?", but this time we are concerned with relationship to a vertical line or plane. Again, the biggest problems are presented when you’re talking about something big. What are the choices - a plumb bob? A machinist’s level? These and similar tools may be used to establish a single vertical reference line, but most have significant drawbacks when dealing with large or awkward objects. Even when they can be used to establish a vertical plane, they cannot determine a particular azimuth orientation of that plane. In the optical alignment method, sweeping a transit’s telescope is used to efficiently define a vertical reference plane. The degree of parallelism between this vertical plane of sight and any other surface can then be determined by measuring the offset between the two planes. As a result, measurements can be made to within 0.001", and even very large vertical areas can be made perfectly plumb.<br /><br />Is it square?<br /><br />... Squareness implies that one plane forms a 90° angle with another intersecting plane. Again, using tools such as steel squares have significant limitations unless the scope of work is small. Also, if the two surfaces in question do not even meet to form something close to a corner, then there are real problems. However, Optical Tooling has several methods of solving this type of problem. OT transits are built specifically to give you the ability to evaluate squareness of the line of sight of two transits.<div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/25114367-114379328583332253?l=geodetic-survey-optics-supply-repair.blogspot.com' alt='' /></div>Chris Gonserhttp://www.blogger.com/profile/07042775573468818639noreply@blogger.com0