V-Block Calculator

°

Zero your indicator on a known master pin, then measure your part. Input the indicator reading to find the actual part diameter.

Positive = Taller, Negative = Shorter
Actual Part Diameter
0.0000
in
Diameter Deviation: 0.0000 in
V-Block Multiplier Factor: --x

Calculate the theoretical height from the V-block vertex to the top and center of a given cylinder.

Vertex to Top (Ht)

0.0000

in
Vertex to Center (Hc)

0.0000

in
V-Block Geometry
The Multiplier Effect

When a cylinder's diameter changes, its height in a V-block changes by a multiplied amount because it sits deeper into the V. For a standard 90° V-Block, the indicator drop is 1.207x the actual change in diameter.

Formulas Used
H_center = (D/2) / sin(Angle/2)
H_top = H_center + (D/2)
Multiplier = 0.5 * (1 + 1/sin(Angle/2))
Checking for Lobing

Centerless ground parts often have 3, 5, or 7 lobes. Measuring them with a 2-point micrometer will show them as perfectly round. A 60° V-Block is the standard method for detecting 3-point lobing.