What do you mean by zero error of a screw gauge how is it accounted for

SuperStock/SuperStock/Getty Images The zero error of a micrometer screw gauge occurs when the flat end of the screw touches the stud or anvil, and the gauge reads other than zero. If there is an error, it results in a positive or negative calculation. However, well-calibrated micrometers that are in good condition measure close to zero; and, they do not introduce a noticeable error. Machinists test the accuracy of micrometers using gauge blocks or rods of a precise thickness. If they discover an error, they re-calibrate the device. They cancel zero error by causing the micrometer to read zero when its jaws close. Proper calibration requires careful attention and cleanliness of the instrument and standard. Most micrometers include a design that allows a pin spanner to turn the barrel in relation to the frame, and this adjusts the zero line. In commercial shops, contracts often dictate that the business calibrate micrometers annually. Even with this amount of caution, machinists should check for zero error using standards every two to three months. In most cases, such checks reveal no errors. Standard one-inch micrometers have readout divisions of 0.001 inch with an accuracy of 0.0001 inch. To ensure accuracy, both the gauge and material being measured must be kept at room temperature. Dirt, abuse and operator mistakes introduce the greatest amount of error into the use of micrometers.

Sometimes when a measurement is taken using a screw gauge, due to some mechanical error, when the studs A and B are brought to contact, the scale is either below or above the main scale. In that case, the screw gauge have a zero error.It can be accounted by the subtracting the zero error from the observed reading, which gives the actual reading of the screw gauge.

What is a zero error? The zero error of a measuring instrument is a result of a calibration error. For example, the speedometer dial in my car shows 10 mph even when the car is parked - the needle cannot go below that position. Many rulers have a bit of plastic (or wood) before the graduations start so if you measure from the end of the ruler the value that you see will always be too small by that amount. Zero error of a spring balance? zerro error in a spring balance affects the accuracy in the weight. To find zero error in spring balance, you have to first find the least count of the spring balance and then suspend it freely, if the outcome is +1, the zero error is +1 and if it is -1 ,the zero error is -1.