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An optical comparator (often called just a comparator in context) or profile projector is a device that applies the principles of optics to the inspection of manufactured parts. In a comparator, the magnified silhouette of a part is projected upon the screen, and the dimensions and geometry of the part are measured against prescribed limits.
The part being checked must pass through the first gap and must stop at the second gap in order to be within specification. The two gaps accurately reflect the top and bottom of the tolerance range. Bore micrometer, typically a three-anvil head on a micrometer base used to accurately measure inside diameters.
The aim of a measurement is to measure the surface on which the dial gauge or spirit level is placed horizontally. For example, to measure the angle of a wedge, the wedge is placed on a horizontal table. The sine bar is placed over the inclined surface of the wedge.
Assembly drawings show how different parts go together, identify those parts by number, and have a parts list, often referred to as a bill of materials. [16] In a technical service manual, this type of drawing may be referred to as an exploded view drawing or diagram. These parts may be used in engineering.
In general, any particular instrument will operate over a small portion of this total range because of the different techniques used to measure different portions of the spectrum. Below optical frequencies (that is, at microwave and radio frequencies), the spectrum analyzer is a closely related electronic device. Spectrometers are used in many ...
Inside small jaws: used to measure the internal diameter of an object (like a hollow cylinder or pipe). Depth probe, or depth rod: used to measure depths of an object (like a small beaker) or a hole. Main scale (metric): marked every millimeter and helps to measure length correct up to 1 mm. Main scale (imperial): marked in inches and fractions.
Every inline series-connected ammeter, including a multimeter in a current range, has a certain resistance. Most multimeters inherently measure voltage, and pass a current to be measured through a shunt resistance, measuring the voltage developed across it. The voltage drop is known as the burden voltage, specified in volts per ampere.
Engineering fits are generally used as part of geometric dimensioning and tolerancing when a part or assembly is designed. In engineering terms, the "fit" is the clearance between two mating parts, and the size of this clearance determines whether the parts can, at one end of the spectrum, move or rotate independently from each other or, at the other end, are temporarily or permanently joined.