# Achieving Joint Constant with Metric Bolts

## How can we specify a coarse thread metric bolt to provide a joint constant of approximately 0.2?

What factors do we need to consider when selecting the thread pitch and diameter of the bolt?

## Specifying a Coarse Thread Metric Bolt for Joint Constant

To achieve a joint constant of approximately 0.2 for clamping two 20-mm steel plates together, we need to consider the thread pitch and diameter of the bolt.

The joint constant (C) is a measure of the clamping force generated by the bolt and nut assembly. It is calculated as the product of the thread pitch (p) and the effective diameter (d) of the bolt. The formula for C is:

**C = p * d**

To achieve a desired joint constant of 0.2, we can rearrange the formula to solve for the required thread pitch (p):

**p = C / d**

Given the desired joint constant (C = 0.2) and assuming the effective diameter (d) of the bolt is 20 mm (same as the steel plates), we can calculate the required thread pitch:

**p = 0.2 / 20 mm = 0.01 mm**

Therefore, to achieve a joint constant of approximately 0.2, you would need a coarse thread metric bolt with a thread pitch of approximately 0.01 mm. Please note that the available standard thread pitches for coarse thread metric bolts may not precisely match this value. In practice, you may need to select the closest available thread pitch that meets your requirements.