1. What is GD&T True Position?

True Position is a geometric dimensioning and tolerancing (GD&T) location control used to specify how much a feature's location may deviate from its "true" position. It's one of the most important and frequently used GD&T controls.

2. How Does the Calculator Work?

The calculator uses the True Position formula:

Where:

• \( dev\_x \) — Deviation in X-axis (inches)
• \( dev\_y \) — Deviation in Y-axis (inches)

Explanation: The formula calculates the radial deviation from true position and doubles it to get the total position tolerance.

3. Importance of True Position Calculation

Details: Accurate position calculation is crucial for ensuring parts fit together properly in assemblies and function as intended. It's widely used in manufacturing and quality control.

4. Using the Calculator

Tips: Enter measured deviations in X and Y directions in inches. The calculator will determine the true position tolerance.

5. Frequently Asked Questions (FAQ)

Q1: Why multiply by 2 in the formula?
A: The multiplication by 2 converts the radial deviation to diameter deviation, which is the standard way to report true position.

Q2: What units should be used?
A: The calculator uses inches, but the same formula works with any consistent unit of measurement.

Q3: How is this different from concentricity?
A: True position controls the location of features relative to datums, while concentricity controls the median points of surfaces.

Q4: When is MMC modifier used with true position?
A: Maximum Material Condition (MMC) modifier is used when the position tolerance can increase as the feature size departs from MMC.

Q5: How does this relate to coordinate measuring machines (CMM)?
A: CMMs often measure deviations from nominal positions, which are then used in true position calculations like this one.