Calculation For True Position

True Position Formula:

\[ TP = 2 \times \sqrt{(x_{dev}^2 + y_{dev}^2)} \]

True Position (TP):

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1. What is 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 calculated as twice the radial distance between the actual and ideal positions.

2. How Does the Calculator Work?

The calculator uses the True Position formula:

\[ TP = 2 \times \sqrt{(x_{dev}^2 + y_{dev}^2)} \]

Where:

\( TP \) — True Position (mm)
\( x_{dev} \) — Deviation in X-axis (mm)
\( y_{dev} \) — Deviation in Y-axis (mm)

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

3. Importance of True Position Calculation

Details: True Position is crucial in manufacturing for ensuring proper fit and function of assembled parts. It provides a cylindrical tolerance zone for hole centers, pins, and other features.

4. Using the Calculator

Tips: Enter the measured deviations in X and Y directions in millimeters. The calculator will compute the total True Position value.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between True Position and concentricity?
A: True Position controls the location of a feature relative to a datum reference frame, while concentricity controls the median points of a surface relative to a datum axis.

Q2: How is True Position measured in practice?
A: Typically measured using CMM (Coordinate Measuring Machine) or optical comparators that can accurately determine feature locations.

Q3: What does the "2" in the formula represent?
A: The multiplier of 2 converts the radial deviation into a diameter value, creating a cylindrical tolerance zone.

Q4: Can True Position be applied to features other than holes?
A: Yes, it can be applied to any feature where location is critical, including pins, slots, and surface points.

Q5: How does material condition modifier affect True Position?
A: Maximum Material Condition (MMC) or Least Material Condition (LMC) modifiers can allow additional tolerance as the feature departs from its material condition.