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ORIGINAL EDUCATIONAL EXAMPLE / NOT A CLIENT PROJECT

Will the assembly retain its gap?

A positive nominal gap is a starting point. This example checks whether the gap stays within an agreed range when every component reaches its dimensional limit.

The review brief

Two components sit inside a 50 mm envelope. For this illustrative exercise, the required final gap is 0.20–0.80 mm.

  • Envelope: 50.00 ± 0.10 mm
  • Component A: 30.00 ± 0.05 mm
  • Component B: 19.50 ± 0.05 mm
  • Functional loop: gap = envelope − A − B
Rigid parts, one dimension and one consistent unit system. Coatings, deformation, thermal growth and assembly effects are excluded from this example.
CALCULATION NOTE / 001Worked example

A small gap. A clear answer.

One envelope. Two components. Worst-case fit.

Envelope · 50.00 ± 0.10 mmA30.00 ± 0.05B19.50 ± 0.05Illustration only · not to scale
Minimum gap0.30 mm
Maximum gap0.70 mm

g = Envelope − A − B
g min = 49.90 − 30.05 − 19.55 = 0.30 mm

Check your own tolerance chain →

Check both extremes.

Smallest gap: 0.30 mm

49.90 − 30.05 − 19.55 = 0.30 mm.

The smallest envelope meets the largest components. The result is 0.10 mm above the assumed lower acceptance limit.

Largest gap: 0.70 mm

50.10 − 29.95 − 19.45 = 0.70 mm.

The largest envelope meets the smallest components. The result is 0.10 mm below the assumed upper acceptance limit.

Conclusion for this example: The 0.30–0.70 mm worst-case range falls within the assumed 0.20–0.80 mm requirement. This establishes dimensional fit only under the stated assumptions. It does not establish seal performance or equipment qualification.