True Position Calculator GD&T

True Position Formula:

\[ TP = 2 \times \sqrt{(X_{actual} - X_{nominal})^2 + (Y_{actual} - Y_{nominal})^2} \]

Actual X Coordinate:

inches

Actual Y Coordinate:

inches

Nominal X Coordinate:

inches

Nominal Y Coordinate:

inches

Position Tolerance Diameter:

inches

Calculated True Position:

Within Tolerance ( inches):

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1. What is True Position in GD&T?

True Position is a Geometric Dimensioning and Tolerancing (GD&T) location control that defines how much a feature's location can vary from its "true" position. It's specified as a diameter within which the axis or center plane of a feature must lie.

2. How Does the Calculator Work?

The calculator uses the True Position formula:

\[ TP = 2 \times \sqrt{(X_{actual} - X_{nominal})^2 + (Y_{actual} - Y_{nominal})^2} \]

Where:

\( X_{actual}, Y_{actual} \) — Measured coordinates of the feature
\( X_{nominal}, Y_{nominal} \) — Theoretical exact position coordinates
\( TP \) — Diameter of the tolerance zone (calculated position deviation)

Explanation: The formula calculates the radial deviation from nominal position and doubles it to get the diameter of the position tolerance zone.

3. Importance of True Position Calculation

Details: True Position is critical in manufacturing for ensuring proper fit and function of assembled parts. It's widely used in automotive, aerospace, and precision engineering industries.

4. Using the Calculator

Tips: Enter actual measured coordinates, nominal design coordinates, and the specified position tolerance diameter. All values must be in the same units (typically inches or millimeters).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between True Position and concentricity?
A: True Position controls location relative to datums, while concentricity controls median points relative to an axis.

Q2: Can True Position be applied to holes only?
A: No, it can be applied to any feature including pins, slots, or other features that require precise location control.

Q3: How is True Position measured in practice?
A: Typically measured with CMMs (Coordinate Measuring Machines) or specialized gauges that can measure feature locations precisely.

Q4: What does MMC/LMC modifier mean in True Position?
A: MMC (Maximum Material Condition) or LMC (Least Material Condition) modifiers allow the position tolerance to increase as the feature size deviates from MMC/LMC.

Q5: How does True Position relate to datum references?
A: True Position is always relative to specified datums that establish the coordinate system for measurement.