Bolt Pattern Pitch Diameter Calculator

Algebraic fitted pitch circle from actual noncollinear planar bolt centers with radial residual, not nominal radius×2. Caller independently establishes units, regime, calibration and applicability; this does not establish design-code compliance, authenticity, operational safety, treatment efficacy or a validated forecast.

Description

A pitch circle can be fitted to measured planar bolt centers.

A pitch circle can be fitted to measured planar bolt centers.^[1]

Fit residuals describe geometric agreement without identifying the intended design or hole tolerances. Use Bolt Pattern Pitch Diameter Calculator to evaluate the supplied inputs under the specific model below.

When to use Bolt Pattern Pitch Diameter Calculator

Use Bolt Pattern Pitch Diameter Calculator to evaluate the supplied inputs under the specific model below. Establish the units, measurement scope and applicable model or recipe assumptions before entering values.

How to use Bolt Pattern Pitch Diameter Calculator and understand its results

Establish the units, measurement scope and applicable model or recipe assumptions before entering values.
Enter Observed bolt centers xy m using the field table and validation rules below, then run the tool.
Read Fitted pitch circle center m, Fitted pitch diameter m, Radial fit rmse m and interpret units, signs, ordering and placeholders as explained below.
If the tool reports an input error, correct that field and rerun. A successful false result, empty match list or unknown-evidence placeholder has the specific meaning described here; check the limitations before applying the result.

Input field	Meaning	Value type	Requirement
observedBoltCentersXyM	Observed bolt centers xy m	array of array	Required; constraints below

Supply 3 to 128 finite planar bolt centers in m with noncollinear geometry. Translate and scale the data, solve the algebraic least-squares circle equations and restore coordinates. Report fitted center, twice the radius and the RMS radial residual in m. The residual measures fit scatter; the tool does not verify equal bolt spacing, drawing tolerances or an exact pitch circle.

circle fit: x²+y² = 2cx×x+2cy×y+c; diameter = 2sqrt(c+cx²+cy²)

Field order, units and branch conditions follow the implementation explanation above.

Output field	Meaning	Value type
fittedPitchCircleCenterM	Fitted pitch circle center m	array of number
fittedPitchDiameterM	Fitted pitch diameter m	number
radialFitRmseM	Radial fit rmse m	number

json

{
  "input": {
    "observedBoltCentersXyM": [
      [
        1,
        0
      ],
      [
        0,
        1
      ],
      [
        -1,
        0
      ],
      [
        0,
        -1
      ]
    ]
  },
  "output": {
    "fittedPitchCircleCenterM": [
      0,
      0
    ],
    "fittedPitchDiameterM": 2,
    "radialFitRmseM": 0
  }
}

Limitations and assumptions

Fit residuals describe geometric agreement without identifying the intended design or hole tolerances. Apply the exact scope and assumptions described above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are stated above; extremely large inputs or outputs can also be rejected. These errors differ from successful results such as false, no matches or unknown evidence.

Alternative or Complementary methods

Use EDM Removal Rate Calculator for a related task: EDM removal can be normalized by spark-on time or total elapsed time.

Use Deep Drawing Blank Diameter Calculator for a related task: A deep-drawing blank estimate balances bottom, wall and trim areas.

References

Bolt Pattern Pitch Diameter Calculator — tool.io

Similar or alternative tools

EDM Removal Rate Calculator
EDM removal can be normalized by spark-on time or total elapsed time.
Deep Drawing Blank Diameter Calculator
A deep-drawing blank estimate balances bottom, wall and trim areas.