Easson2D Help Center

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简体中文

Position ​

Overview ​

Position tolerance evaluates the deviation of a point, circle center, or spatial center from its theoretical position. In Easson2D, the system first determines the theoretical position, then calculates the distance between the actual and theoretical positions, and outputs the result as a diameter tolerance zone value.

Steps ​

Step 1: Click the Function Button ​

Click Position in the Tolerance menu to open the geometric tolerance dialog.

Step 2: Select the Measured Element ​

In the Vision Area or Geometry Area, select a point, circle, or arc element as the measured element.

Step 3: Configure Reference ​

  • If a true theoretical position is known, enter the coordinate values directly in the dialog
  • If a datum element is required, check Datum Element and click to select the datum element

Step 4: Create Label (Optional) ​

To create a label, check Create Label before confirming. Left-click in the Vision Area or Geometry Area to place the label at the desired position.

Calculation Principles ​

The system first determines the theoretical position, then calculates the distance between the actual and theoretical positions, and outputs the result as a diameter tolerance zone value (result × 2).

Position diagram

Formula ​

2D:

d = √[(x₁ - x₂)² + (y₁ - y₂)²]
Position = 2 × d

3D:

d = √[(x₁ - x₂)² + (y₁ - y₂)² + (z₁ - z₂)²]
Position = 2 × d

Example Calculation (2D, with datum) ​

Given:

  • Actual center A = (10.012, 5.009)
  • Datum center B = (0.000, 0.000)
  • Theoretical offset = (10.000, 5.000)
  • Theoretical center T = B + offset = (10.000, 5.000)

Step 1: Determine the theoretical center

Theoretical center T = (10.000, 5.000).

Step 2: Calculate the distance from actual to theoretical center

d = √[(10.012 - 10.000)² + (5.009 - 5.000)²]
d = √[(0.012)² + (0.009)²]
d = √(0.000144 + 0.000081)
d = √0.000225 = 0.015 mm

Step 3: Output as diameter tolerance zone

Position = 2 × d = 2 × 0.015 = 0.030 mm.

Note: The result is multiplied by 2 because the system outputs the diameter of the tolerance zone, not the radius.

Notes ​

  • The measured element can be a point, circle, or arc
  • True position coordinates are optional — enter them when the ideal coordinates of the measured element are known
  • The datum element is also optional — use it only when required by the tolerance specification
  • Labels can be placed flexibly as needed