Slip gauges - requirements

Slip Gauge

Slip gauges were first developed by Johnson, and sometimes also called as ‘Johnson Gauge

Blocks’.Slip gauges are the universally accepted ‘standard of length’ in industries. These are the

simplest possible means of measuring linear dimensions very accurately.

Need of Slip Gauges:

For tool-room and other precision work, the ordinary methods of measurement are not always

accurate. Micrometer and vernier caliper can be used to check tolerance fine within 0.002 to

0.02 mm, but for fine tolerance they are not effective. Thus there is a need of instrument which

can measure fine tolerance limit.

Grades of Accuracy of Slip Gauges:

Slip gauges are made in five grades of accuracy. Calibration grade, grade 00, grade 0, grade I,

and grade II, in the decreasing order of accuracy.

The means to do so are ‘slip gauges’. They can be used to measure tolerances in the range of

0.001 to 0.0005 mm very accurately.

Grade 0, grade I, grade II are used for general workshop purpose and are known as working

gauge blocks, whereas, calibration grade (master gauge blocks) and grade 00 (Inspection gauge

blocks) are used only for checking other types of blocks.

(i) Calibration Grade:

This is special grade and is used for experimental work, research work and for measurement and

inspection of other gauges (grades).

(ii) Grade 00:

This is also termed as inspection gauge block. This is used for highest precision work such as

measuring Grade I and II.

(iii) Grade 0:

This is used for tool room or machine shop inspection.

(iv) Grade I:

This is used for more precise work such as setting up sine bars, checking gap gauges,

measurement of components, tools etc.

(v) Grade II:

This is used in workshop for rough checks, for ordinary inspection work, for setting up machine

tools, and for measurement where production tolerances are relatively wide.

Uses of Slip Gauges:

Slip gauges are important means of measurement in industries and laboratories.

Their uses are:

1. They universally accepted as a “Standard of length”.

2. They used for direct precise measurement where accuracy of work piece being measure is

high.They used with high-magnification comparators, to establish the size of the gauge

blocks.

3. They are used for checking the accuracy of measuring instruments.

4. They are used to setting up a comparator to specific dimension.

5. They are used to check a batch of components quickly and accurately.

Taper Measurement by Using Slip Gauage

1. By using sine bar.

2. By using Dial Indicator.