Optical Tooling and Alignment

Support of On-site Corrective Machining Industry Turbines Compressors Gears presse	Power Generation, Multi-Component Rotating Equipment Fossil Generating Facilities Hydro-Electric Plants Nuclear Power Generatio	Machine Tool Evaluation Evaluation of Existing Machinery Precise Setting of New Machine Tools Evaluation & Alignment of Jigs & Fixture
Marine-Precise Alignment without a Gravity Reference of Foundations, Engine Bases, Gear Reducers, etc. Barges Dredges Tug Boats Drilling Platforms Ship Propeller Shaft	Aircraft & Aerospace Frames Fixtures Coordinate Control of Contour Surface	Aluminum, Steel, & Copper Mills Extruders Roll Alignment Rotating Equipment Gears Presse
	Petro-Chemical Compressor Trains Pumps Gearboxes Turbines (Steam and Gas	Paper Mills Roll Alignment Line Shaft and Bearing Alignment Drive System Analysi

What Are the Basics of Optical Tooling?

In the erection of industrial equipment or in the alignment of precision systems, four basic questions must be answered in order to insure proper equipment operation. These four fundamental questions are: Is it straight?...Is it flat?...Is it plumb?...Is it square?

A number of techniques have been developed to make these measurements; however, many of them result in inaccuracies so great that the efficient and precise operation of the equipment involved is seriously endangered. The science of optical metrology and alignment makes it possible to achieve the highest degree of accuracy in answering these four important question. It is no longer necessary to extrapolate readings, or to make constant adjustments and calculations. In optical alignment, direct precision measurements are made rapidly and consistently.

Is it straight?

In aligning several points, a tight wire is often used as a reference line. This technique has numerous drawbacks resulting in considerable inaccuracy. First of all, wire has weight, which causes it to sag; over long distances this sag can become considerable. In addition, wire vibrates, can bend or kink, and when stretched in the area to be measured, equipment cannot be moved around for fear of disturbing the wire reference line.

In optical alignment technique, the line of sight of an alignment telescope is used as a reference line, instead of the tight wire. The invisible line of sight reference has no weight, cannot sag, kink, or be disturbed, nor is it a safety hazard. It constitutes a precise, unvarying reference, determining straightness to within thousandths of an inch.

Is it flat?

In order to determine flatness for leveling operations, a shop level and a straightedge may be employed; however, over large horizontal areas, the shop level must be moved from part to part. Consequently, one can only tell the degree of flatness of each individual surface upon which the level is place. Whether the whole area to be covered is flat is still in doubt. Obviously, flatness over a considerable area must be assured in the erection of large machinery such as paper processing equipment. Shop level techniques simply do not offer the degree of precision required.

Optical alignment methods overcome these disadvantages and assure levelness to within a few thousandths of an inch, regardless of how large an area is to be covered. This high degree of levelness is accomplished by sweeping the telescope back and forth from right to left, so that the line of sight mentioned above becomes an invisible, horizontal plane of sight, giving a precise horizontal reference plane.

Is it plumb?

A plumb bob may be used to establish a single vertical reference line. Of course, as vertical distances increase, the plumb bob system becomes cumbersome and inaccurate. For one thing, it takes a long time for the plumb bob to steady itself. Also, it can easily be swayed by vibration, air currents, and other disturbances which are bound to be encountered.

In the optical alignment method, a jig transit or precise electronic theodolite is used to erect 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 within .001". and even very large vertical areas can be made perfectly plumb.

Is it square?

Perfect squareness implies that one plane forms a 90° angle with another intersecting plane. When a steel square is used to test for this condition, the results can be very misleading. Such measurements rely upon the trueness of the steel square, which can vary from square to square with time. In addition, steel squares have a definite limit in their physical dimensions and consequently the testing of very large surface becomes inaccurate, slow and cumbersome. Optical alignment overcomes all these disadvantages and offers a quick and precise method for determining squareness.

One method is to use two telescopes, each creating its own line of sight reference. One telescope carries a precision mounted mirror on its axle; the second telescope is aimed at the mirror, so that its line of sight is reflected back on itself. Once this condition has been achieved, the two lines of sight are precisely at right angles, and the squareness of the two planes can be established with a great degree of precision.