Description
Residual circular blank clearance after supplied frame effective diameter, planar decentration and radial allowance.
Optical calculations distinguish lens power in diopters, prism notation, angular axes, geometric distances, and visual-acuity reporting scales. Sign conventions and length units are especially important when a formula combines power with decentration or vertex distance. A supplied model term is separate from a validated visual test or prescription.
Residual circular blank clearance after supplied frame effective diameter, planar decentration and radial allowance.
When to use this tool
Use Spectacle Frame Effective Diameter Clearance when you need this explicit optical, chart, frame, axis, or reference conversion with compatible supplied units.
How to use the tool and how it works
- Enter blankDiameter, effectiveDiameter, horizontalOffset, verticalOffset, radialAllowance. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read requiredDiameter, residualClearance, fits. Inspect fits before interpreting the associated values.
For nonnegative blankDiameter, effectiveDiameter, and radialAllowance return requiredDiameter=effectiveDiameter+2*hypot(horizontalOffset,verticalOffset)+2*radialAllowance, residualClearance=blankDiameter-requiredDiameter, and fits on nonnegative clearance.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| blankDiameter | Blank Diameter | Required. Finite number; minimum 0. |
| effectiveDiameter | Effective Diameter | Required. Finite number; minimum 0. |
| horizontalOffset | Horizontal Offset | Required. Finite number. |
| verticalOffset | Vertical Offset | Required. Finite number. |
| radialAllowance | Additional radial length allowance, counted twice in the diameter. | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| requiredDiameter | Required Diameter | Required. Finite number. |
| residualClearance | Residual Clearance | Required. Finite number. |
| fits | Fits | Required. Boolean. |
{
"input": {
"blankDiameter": 70,
"effectiveDiameter": 50,
"horizontalOffset": 3,
"verticalOffset": 4,
"radialAllowance": 1
},
"output": {
"requiredDiameter": 62,
"residualClearance": 8,
"fits": true
}
}Limitations and assumptions
- Lengths need one unit. The conservative circular budget does not trace actual lens shape, verify centration or edging tolerances, or establish safe spectacle manufacture and clinical fit.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the appropriate complete optical or measurement model when a scalar term is insufficient. Verify power, axis, length, notation, and reference conventions before applying the result within a broader assessment.
References
Similar or alternative tools
- Spectacle Asymmetric Frame Decentration Pair
Explicit planar model decentration and conservative circular-blank budget, without selecting spectacle fitting measurements.
- Oral Surgery Phantom Screw Clearance Gap
For nonnegative holeDiameter, screwDiameter, and eccentricity return radialClearance=(hole-screw)/2, minimumGap=radialClearance-eccentricity, and fits when holeDiameter-screwDiameter>=2*eccentricity.