Which are the commonly available grades of 'V' blocks?

Explanation:

‘V’ blocks:

• ‘V’ blocks are devices used for marking and setting up work on machines.
• The included angle of the V is 90° in all cases.
• ‘V’ blocks are finished with high accuracy in respect of dimension, flatness, and squareness.

Grades and materials:

• ‘V’ blocks are available in Grade ‘A’ and Grade ‘B’.

Grade A:

• A grade ‘V’ blocks are more accurate and are available only up to 100 mm in length.
• These are made of high-quality steel.

Grade B:

• B grade ‘V’ blocks are not as accurate as A grade ‘V’ blocks and these are useful for general machine shop work.
• These ‘V’ blocks are available up to 300 mm in length.
• Grade B ‘V’ blocks are made of closely-grained cast iron.

Designation:

• ‘V’ blocks are designated by the nominal size (length), the minimum and maximum diameters of the workpiece capable of being clamped, and the grade and the number of the corresponding B.I.S. standard.
• In the case of matched pairs, it should be indicated by the letter ‘M’.
• For ‘V’ blocks with clamps, it should be indicated as ‘with clamps’.

Example:

• A 50 mm long (nominal size) ‘V’ block capable of clamping workpieces between 5 to 40 mm in diameter and Grade A will be designated as - ‘V’ block 50/5/5-40 A (B.I.S. 2949).
• In the case of a matched pair, it will be designated as ‘V’ block M50/5-40 A (B.I.S. 2949).
• For ‘V’ blocks supplied with clamps, the designation will be ‘V’ block with clamp 50/5-40 A (B.I.S.2949).