O-ring squeeze: 20–30% static

Compress an O-ring 20–30% of its cross-section for static seals, only 10–20% for dynamic.

Why it works

Too little squeeze leaks; too much accelerates compression set and, in dynamic service, friction and wear.

Do it exactly

Estimate with the rule, then check it against the calculator that models it properly.

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More in Mechanical

• The bolt-torque shortcutTightening torque ≈ 0.2 × preload × bolt diameter (dry steel).
• Torque mostly fights frictionRoughly 90% of tightening torque is lost to friction; only ~10% actually stretches the bolt.
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• Depth beats width, cubedDouble a beam’s depth and its deflection drops 8-fold. Double its width and it only halves.

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