Starrett is one company that produces micrometers -- tools used to measure dimensions from several centimeters to less than a millimeter. The object is placed on the anvil side of the micrometer, then the spindle side is closed until it touches the object. You then read the markings on the sleeve and thimble to find the size of your object. Although not a common maintenance procedure for micrometers, you may have to disassemble your Starrett micrometer for cleaning or calibration.
Lay the newspaper onto your work surface. This keeps your work area clean and prevents any dirt or dust on your work surface from getting into the micrometer.
Find the ratchet stop on your Starett micrometer. The ratchet stop is located at the end of the micrometer farthest from the "jaws" of the tool.
Remove the ratchet stop. The ratchet stop either twists off (you might need to hold the micrometer in a vice to twist the ratchet stop off) or a screw at the end needs to be removed to take off the ratchet stop. Set the ratchet stop aside.
Pull out the spindle from the sleeve and thimble. If it doesn't come out easily, check that the lock nut on the sleeve is unlocked. Set the spindle aside
Slide the thimble off, twist it loose if it doesn't slide straight off. Set the thimble aside.
Remove the screw holding the anvil onto the frame of the micrometer. Set the anvil aside. The frame and sleeve are one piece and do not come apart in Starrett micrometers.
Keep your work area clean to avoid getting dust and dirt in the disassembled micrometer.
Taking apart the micrometer could void any warranties on the tool.