What should be the thumb rule of designer to choose precision level for various parts and dimensions

The thumb rule for a designer to choose the precision level for various parts and dimensions depends on several factors:

1. Functionality: The designer must first understand the functionality of the part. If the part is critical for the operation of the overall system, then a high level of precision is required.

2. Tolerance: The designer must also consider the tolerance levels of the part. If the part can tolerate a high level of variation, then a lower level of precision may be acceptable.

3. Cost: Higher precision levels often come with higher costs. The designer must balance the need for precision with the cost constraints of the project.

4. Manufacturing Process: The precision level may also depend on the manufacturing process. Some processes can achieve higher precision levels than others.

5. Material: The material of the part can also affect the precision level. Some materials can be machined or molded to a higher precision level than others.

6. Standards and Regulations: In some industries, there are standards and regulations that dictate the precision level of certain parts.

In conclusion, the thumb rule for choosing the precision level for various parts and dimensions is to consider the functionality, tolerance, cost, manufacturing process, material, and any applicable standards or regulations.