This tool is handy when you want a reasonable tightening torque estimate but your manual does not provide a value. It uses T = K × D × F to compute an approximate torque.
1) Pick a system (metric or inch), then the bolt diameter.
2) Strength class: choose the closest matching grade/material. Higher yield strength generally means higher allowable preload and torque.
3) Friction factor K: this is the biggest real-world uncertainty. Lubrication, coatings, thread condition, and washers can change K a lot.
4) % of yield load: for non-critical bolts, conservative values (for example 60-70%) are often safer than pushing to the limit.
5) Thread type: affects the stress area (As) used in the estimate.
Practical notes:
- For critical joints (brakes, steering, suspension, engine internals, safety-related fasteners), use manufacturer procedures and applicable standards.
- Torque is not the same as preload; torque is just a proxy and depends heavily on K.
- When unsure, use a lower percentage and verify by inspection and re-torque checks if appropriate.
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