Metric 60° Thread Geometry & Stress-Area Worksheet
Evaluate an explicitly defined symmetric 60° metric-thread model from nominal diameter d and pitch P. The worksheet does not choose an ISO diameter–pitch combination,derive manufacturing limits or certify a tolerance class.
Enter the controlled thread definition
Kopírovat d a P from the applicable drawing,product standard or licensed thread standard. Both inputs are millimetres. A designation alone is not evidence of tolerance limits.
Fundamental triangle H
Basic pitch diameter d₂=D₂
Basic-profile minor line d₁=D₁
Stress-model diameter dₛ
Nominal stress-area screen Aₛ*
Circle area at dₛ,A₃*
Exact model used by the code
| Výstup | Equation | Meaning and boundary |
|---|---|---|
| fundamental triangle | H=√3·P/2 | Height of the complete 60° fundamental triangle;not actual thread height. |
| basic pitch diameter | d₂=D₂=d−3H/4 | Basic-profile reference value with no allowance or tolerance. |
| basic-profile minor line | d₁=D₁=d−5H/4 | Reference profile line only;external and internal design/limit profiles differ. |
| stress-model diameter | dₛ=d₁−H/6=d−17H/12 | A separately named calculation diameter;the former page misleadingly labelled this as the bolt’s actual minor diameter d₃. |
| nominal stress-area screen | Aₛ*=π[(d₂+dₛ)/2]²/4 | Common nominal fastener stress-area arithmetic;not a strength,proof-load,strip or fatigue result. |
| circle at stress diameter | A₃*=πdₛ²/4 | Geometric circle only;not a tolerance-minimum net section. |
All variables are in millimetres and areas are in mm². The code evaluates the equations directly with Math.sqrt(3) a Math.PI;it does not use rounded decimal coefficients internally.
Standard scope and source status
ISO261:1998,Edition2,remains published and was confirmed in2024. Its general plan defines ISO general-purpose metric thread combinations;the public card states that basic dimensions are in ISO724 and tolerances are in ISO965-1.
ISO724:2023,Edition3,is the current published basic-dimensions standard. It applies to metric fastening screw threads and refers to design profiles in ISO68-1:2023,Edition2. The former page did not identify these current editions and presented formula outputs as if they were usable tolerance dimensions.
Manufacturing limits require an applicable tolerance class and current licensed data. ISO965-1:2026,Edition5,now supplies tolerance-system principles;selected published limit tables are covered by ISO965-6:2025. This worksheet intentionally does not reproduce their closed tables. Exact table rows,clauses and permissible diameter–pitch combinations remain NEEDS_LICENSED_SOURCE.
ISO898-1:2013,Edition5 with Cor1:2013,was confirmed in2025 and is marked to be revised. Its public scope is restricted to specified carbon/alloy-steel bolts,screws and studs,thread ranges,temperature and tolerance standards. The public card does not expose the exact stress-area clause;therefore this page labels the calculation non-normative and does not claim ISO898-1 conformity. As a published numerical cross-check,a fastener manufacturer’s coarse-thread table reports M12 nominal stress area84.3mm²,matching this worksheet after rounding.
What was corrected
The former tool called H “thread height”,called the stress-calculation diameter d₃ the bolt minor diameter,and displayed basic values as “all key dimensions” without any tolerance class. It also supplied a partial hard-coded diameter/pitch list under a “full reference table” label and silently defaulted to M12.
The replacement starts blank,requires the controlled d/P source,removes presets,the incomplete ISO table,URL state and local history,and rejects partial or nonphysical values. It separates basic-profile geometry from stress-area arithmetic and removes claims that fine pitch universally resists vibration loosening or guarantees greater load capacity.
Use and interpretation
- Verify the exact diameter–pitch combination and designation in the governing drawing or licensed standard.
- For manufacture or inspection,use the specified tolerance class and current limit/gauging standards—not the basic values shown here.
- For bolt strength,use the applicable product/material standard,actual stress-area table,property class,temperature and failure mode. Larger nominal area alone does not establish joint capacity.
- For vibration,self-loosening and preload,assess the complete joint,clamp length,preload,friction,transverse motion and locking method;pitch alone is not a universal pass/fail criterion.
