Micrometer is one of the precision instrument and it used to measure the thickness of a piece. There are four types of micrometer which are inside micrometer, outside micrometer, depth micrometer and screwthread micrometer.
There are certain procedures must be followed prior using the micrometer. Firstly, check the calibration tag and make sure tools calibrated. If it is not calibrated, send to standard room. There are several infos shown on the sticker which are serial number, part number, next due date, approval name and stamp. Check all these infos and make sure it is the latest date. Next, make sure the tool clean. Check for any defect such as corrosion and pitting on micrometer. After that, spin the ratchet screw to move the spindle close to the anvil. Check the scale to make sure there is no zero error. It is when the number zero '0' coincide. Then, check the smoothness of the movement of the spindle.
While using the micrometer, make sure the surface of the piece that is going to be measured is clean. Place the piece in an appropriate position. Next, move the spindle until it touches the surface perfectly and then 'click' appear two times. After that, lock the nut and remove the piece from micrometer. After all the above procedures are done, take measurement and make sure eye level coincide with the scale to avoid parallex error. If you find difficulty in reading, request for magnifying glass from the store man.
After using micrometer, clean it. Remember to slightly oil the micrometer and turn the thimble so that the spindle close to the anvil. However, avoid the spindle from contacting the anvil to prevent galvanic corrosion. Next, keep it in the box and store in place with controlled humidity & temperature & not exposed to heat and avoid dropping tool at all time.