Machining
Measuring over pins
In short
Three-wire measurement and best wire; over-pin measurement of a male or female dovetail. Example with the default values: Over wires M = 10.4117 mm.
Calculation
Example calculated with the tool’s default values.
Inputs
- Part
- Thread (three wires)
- Profile
- ISO metric, UNC/UNF (60°)
- Thread
- M10
- Nominal Ø d
- 20 mm
- Pitch P
- 2.5 mm
Results
- Over wires M
- 10.4117 mm
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Other results of the example
- Wire Ø used
- 0.895 mm
- Best wire
- 0.8660 mmNearest Zeiss wire: 0.895 mm
- Basic pitch Ø
- 9.026 mm
- No lead-angle or measuring-force correction: fine for single-start threads; for calibration, EURAMET cg-10.
Step-by-step calculation
Basic pitch Ø
d2 = d − 0.649519 · P
10.000 − 0.649519 × 1.500 = 9.026 mm
Best wire
dD = P / (2 cos(α/2))
1.500 / (2 cos 30.0°) = 0.8660 mm
Measurement over wires
M = d2 + dD (1 + 1/sin(α/2)) − (P/2) cot(α/2)
9.026 + 0.895 × 3.0000 − 0.750 × 1.7321 = 10.4117 mm
M by wire size (d2 9,026)
| Wire (mm) | M (mm) |
|---|---|
| 0.620 | 9.5867 |
| 0.725 | 9.9017 |
| 0.895 | 10.4117 |
| 1.100 | 11.0267 |
Limits
Indicative results: they replace neither the applicable standards nor the job drawings and instructions. Check the values entered and the result before doing the work.
Sources
- Martin + Tschopp (BRW), Three-wire thread measurement method V1.1 : Pige idéale dD = P / (2 cos α/2) ; série de piges Zeiss (DIN 2269:1998 tableau B.2) ; EURAMET cg-10 (link)
- ISO 724 / ISO 228-1 / ISO 2904 : Ø sur flancs de base : d − 0,649519 P (60°), d − 0,640327 P (55°), d − 0,5 P (Tr 30°)
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