When outside micrometer has a negative error, correct reading can be taken by adding the negative error in the actual reading.
21) An outside micrometer has a negative error. The correct reading can be taken by
Adding the negative error in the actual reading
Related ISRO Technician-B Turner Question Paper - 2015 (Set - 1) with Answer Key
The zero reading (minimum range) of the outside micrometer while measuring with a 50 to 75 mm micrometer is 50 mm.
Nut & bolt
Make surface flat so that bolt head can take proper seat on the surface
Spot facing is a machining operation for producing a flat seat for bolt head, washer or nut at the opening of a drilled hole. The tool is called a spot facer or a spot facing tool.
Spot facing is similar to counter-boring, except that it is shallower. Tools that are used for counter-boring can be used for spot facing as well.
The drill chucks are held on the machine spindle by means of an arbor fitted on the drill chuck.