A dial gauge is a measuring instrument used in various industries to measure accuracy. It has a spring-loaded mandrel attached to a clock face dial, and the spindle movement displays the distance measurement. It is used in manufacturing, engineering, science, laboratories, automotive repair shops, and woodworking. The sizing specifications vary widely, and most modern models have digital readouts. It is essential to mount the instrument on a base to increase accuracy. When purchasing, customers should consider the intended usage, whether there are accessories available, and the differentiation of dial test indicators.
A dial gauge, also sometimes called a watch pointer, dial indicator, probe pointer, or comparator, is a measuring instrument used in many industries where accuracy is needed, such as manufacturing, engineering, and science. The indicator is a spring-loaded mandrel, or plunger, attached to a clock face dial. As the spindle moves in and out of the gauge, a needle on the dial displays the distance measurement, which in turn reveals the depth of the depression. Using this tool is normally pretty straightforward. An operator lifts the indicator spindle with a lever, slides the object he wishes to measure under it, and lowers the spindle. If the part deviates from the reference, the gauge dial records the deviation. On some gauges with a larger range, a smaller face within the larger tracks follows each spin.
primary uses
These types of tools are used in a wide variety of industries. In manufacturing, professionals typically use them when setting up the machine to center the stock and determine the accuracy of the lathe or mill alignment. Production machinists also use gauges to monitor the depth of holes, grooves and protrusions. Many quality control engineers use them to check for variation in tolerance of machined parts.
Indicators are also important in laboratories for recording and measuring small movements, both of mechanisms and particles. In automotive repair shops, they help mechanics fit new rotors into disc brakes, where the tolerance can be as low as 0.0019″ (0.05mm). In home woodworking situations, craftsmen can use them to set up lathes and saws and monitor hole depths. In essence, this tool can be very useful whenever a person needs an accurate reading or calibration, regardless of the setting.
Sizing specifications
Sizing specifications for this tool can vary widely. Gauges typically range from 0.250 inch to 2 inch (6.35 mm to 50.8 mm) and provide measurements in 0.001 inch (0.0254 mm) increments. Some specialty tools measure in the range of about 0.015 inch (about 0.25 mm) while others go up to 12.0 inch (about 30.5 cm). Graduation marks on the dial can range from 0.00005 inch to 0.001 inch (approximately 0.001 mm to 0.01 mm) in typical gauges.
Most modern models have digital readouts rather than the more traditional clock face reading. Among other things, digital technology makes it easier to switch from imperial to metric measurements. Some also have the ability to transfer measurement data to a computer or wirelessly store the data in the cloud or other remote database.
Importance of secure mounting
In most cases these instruments are not accurate unless mounted on a base. The typical gauge mount is a magnetic base mount that has an arm, or arms, to hold the measuring apparatus in a variety of positions. Sometimes engineers design unique stands to support tools for special jobs.
Having the indicator attached to a rigid base or stand helps the user in two ways. First, the meter is more accurate without user interference. Another benefit of a base is that it provides the mandrel with a major part or reference point against which to measure the item. Usually a train driver establishes a reference point by turning the large dial hand to zero before measuring a depth.
Purchase considerations
There are a couple of things customers should consider when purchasing these tools, but much of the decision will be driven by intended usage. Because coolants, oil, water, and other contaminants can ruin the tool, most machinists buy waterproof and dustproof gauges. Better gauges have jeweled movements, which typically offer a better lifespan even though they may cost more up front. A buyer should also usually think about whether there are meter accessories available, such as mounts, additional contact points, and replacement parts, and if so, how easy they are to obtain.
Differentiation of dial test indicators
A similar tool known as a dial test indicator is often similar to and can sometimes be used in place of the more standard dial indicator, but is usually more accurate and has more nuanced uses as well. Typically, test indicators have a smaller measuring range and are more accurate. Instead of having a chuck, they have a lever arm with a ball point that moves up and down. In many situations, a test comparator can perform measurements that a comparator cannot. Most serious machinists have and use both tools.
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