An inside micrometer is a precision measuring instrument which measures with an accuracy of 0.01mm. An inside micrometer is used to measure the diameter of holes. To measure the distance between internal parallel surfaces like slots
PARTS OF INSIDE MICROMETER
The following are the parts of an inside micrometer
Micrometer head: – It consists a sleeve, a thimble, an anvil and locking screw for extension rods
Extension rod :– This is fitted in the hole provided in the barrel of the micrometer head. It provides another measuring surface. It is available in different sizes.
Locking Screw :– It is used to lock the extension rods.
Handle :– It is fitted in the threaded hole provided in the
Micrometer head :-. It is used to hold the micrometer assembly while measuring deep bores.
Spacing collar :- It is added to the extension rod for additional length. It is available in different sizes.
The range of inside micrometer
Using the different sizes of extension rods and spacing collars the following ranges of measurement can be taken
25-50mm, 50-200mm, 50-300mm, 200-500mm,200- 1000mm.
Inside micrometer Ranges of extension rod for (50 – 200mm) Inside micrometer Checking parallelism of surfaces of deep bores
An extended handle can be used while measuring deep bores. for checking the parallelism of surfaces of
the bore.
Find out the readings at 2 or 3 places i.e. one reading at. the top, another reading at the middle and the third reading the bottom of the bore. If all the three readings are the same, then the surfaces of the bore are parallel. Any variation in the readings shows an error in the bore
