Toolchest · Datasheet

Accumath Toolchest — Fasteners & Threads Dataset: Notes

File: accumath-fasteners-threads.csv Compiled: 2026-10-20 Row counts: 202 total — thread_inch 49, thread_metric 51, bolt_grade 14, torque 88.

Basis of the data (legal)

Every value in this dataset is a published fact taken from an openly published chart or catalog table, with the source named in the source column of each row. Thread dimensions, strength values, and torque figures are facts, not creative expression; they are recorded here as published, with attribution. No table was copied from an ASME, ISO, or SAE standards document itself — all values come from open manufacturer/industry republications of that factual data (Fastenal, Portland Bolt, Specvise, CML Supply, and similar published charts). Where a value could not be verified on an opened page, the cell was left out — nothing in this file is estimated, interpolated, or computed from a formula to fill a gap.

Column conventions

One CSV holds four sections, distinguished by the table column. Units are per section:

• thread_inch: all diameters and pitch in inches. pitch is the thread pitch = 1/TPI (definitional). minor_dia is the internal (nut) basic minor diameter. Diameters are basic dimensions as published by the source chart, rounded to 0.001 in (one row excepted, see Gaps).
• thread_metric: all dimensions in millimetres. minor_dia is the internal basic minor diameter (ISO 724, D1). series_or_grade is coarse or fine.
• bolt_grade: strengths in the unit given by strength_unit (psi for SAE/ASTM rows, MPa for ISO rows). Values are specification minimums as published.
• torque: torque_unit is ft-lb for inch rows and N-m for metric rows. ASTM A325/A490 rows carry the published range (e.g. 100-117) instead of a single value — see the torque section below.

Section 1 — thread_inch (49 rows: 25 UNC + 24 UNF)

• Geometry (major, pitch, minor diameters; TPI): Yijin Solution UNC/UNF thread size chart, which republishes the ASME B1.1 basic dimensions. Spot-checked against the Echo Engineering UNC/UNF chart and the Specvise inch thread chart; values agree to chart rounding (e.g. 1-8 UNC minor 0.865 vs basic 0.8647).
• Tap drills: Specvise inch tap drill chart (recommended drills for approximately 75% thread engagement) for #0 through 1-1/2 in where published there; CML Supply machinist tap drill chart (ANSI standard vee-thread) for the larger fractional sizes. Tap drills are published drill selections only — no tap drill in this file was computed from a formula. Published charts occasionally disagree by one drill size (e.g. #2-56 UNC: #50 vs #51); in those cases the Specvise 75%-thread chart was followed, as named in the row.
• There is no #0 UNC — the UNC series starts at #1-64. #0 appears only as #0-80 UNF. UNEF (extra fine) threads are not included.

Section 2 — thread_metric (51 rows: 25 coarse + 26 fine, M3–M64)

• Geometry: Metric & Multistandard Components Corp. table of basic dimensions per ISO/R 724 (major, pitch, and internal minor diameters). Coarse sizes are the preferred ISO series M3–M64; fine rows give the commonly designated fine pitch for each size (two for M10 and M12, which are both in wide use). Cross-checked against the Echo Supply metric thread chart where the two overlap (e.g. M10x1.5 minor dia 8.376 mm in both).
• Tap drills: Specvise metric tap drill chart (M3–M30 coarse; common fine pitches to M16), Speakman tap drill chart (coarse M33–M64; fine M18–M30), BS 3643 tap drill guide (small fine pitches; fine M33–M64). All are published drill selections; none was computed as diameter-minus-pitch by the compiler. (Note: some published charts do list the bare d−P figure, e.g. 6.75 mm for M8, where drill-selection charts list the standard 6.8 mm drill — the drill-selection value is what is recorded here.)

Section 3 — bolt_grade (14 rows)

• SAE J429 Grades 2, 5, 8 and ASTM A325, A490, A354 BD: Fastenal Technical Reference Guide, fastener grade/specification chart (values as published there). A325 and A490 are now maintained under ASTM F3125 (as Grades A325 and A490); the property values are unchanged and are listed under both names in the designation column.
• ISO property classes 8.8, 10.9, 12.9: ISO 898-1 property class data as published in open grade charts (Prince Fastener ISO 898-1 chart). Class 8.8 has two rows because its proof/yield/tensile values step up above 16 mm diameter; hardness is the single published HRC range for the class.
• ASTM A490 tensile strength is a 150,000 psi minimum with a 173,000 psi maximum in the specification; the minimum is recorded.
• Hardness is recorded exactly as published (core_hardness), in the scale the source uses (Rockwell B, Rockwell C, or HRC).

Section 4 — torque (88 rows) — READ THIS BEFORE USING

Torque values are recommendations, not physical constants. A torque number is only a recipe for reaching a target bolt tension (clamp load) under an assumed friction condition. The same bolt, at the same torque, will produce different tension with different thread condition, plating, lubrication, surface finish, and reuse history. For any joint where loosening or failure matters, the torque–tension relationship must be established on the actual parts — that is Fastenal's own printed caution on its torque charts, and it applies to every row in this section.

• Basis: All values target a clamp load of 75% of proof load, computed by the publishers from T = K·D·F with K = 0.20 — plain finish, dry (no lubricant, no plating effect). Inch rows: Portland Bolt bolt torque chart, "Plain" column. Metric rows: Fastenal Technical Reference Guide, metric torque-tension table (N-m edition), K = 0.20 column.
• Dry vs. lubricated — the values assume the stated (dry) condition. Lubrication changes everything: with oil, moly, or wax on the threads, the friction factor drops (Fastenal publishes K = 0.15 for lubricated fasteners), so the same torque produces roughly one-third more tension — enough to yield or snap a bolt that the dry torque was safe for. Never apply a dry torque value to a lubricated fastener, and never apply a lubricated value to a dry one. If the joint is lubricated, use a lubricated-condition chart (the publishers' K = 0.15 columns run about 25% below the dry torque for the same tension).
• Friction scatter: Even with condition controlled, torque-controlled tightening typically scatters the achieved clamp load by about ±25% (industry rule of thumb; the spread comes from friction variation, which consumes roughly 90% of applied torque — only about 10% of the torque stretches the bolt). Treat every value in this section as the centre of a wide band, not a precise setting.
• A325 / A490 rows are ranges, because Portland Bolt publishes minimum–maximum torque ranges for those structural grades rather than single values; the range is recorded as published. Portland Bolt's chart is based on the original ASTM A325 specification (the grade now lives in ASTM F3125); values are unchanged.
• Grade 2 note: Portland Bolt notes its Grade 2 torque calculations cover bolts 1/4–3/4 in diameter and up to 6 in long; the chart's published values for larger Grade 2 sizes are recorded as printed. Note the Grade 2 torque at 7/8 in (166 ft-lb) is lower than at 3/4 in (173 ft-lb) — that is correct as published, because Grade 2 material strength drops above 3/4 in diameter (see the two Grade 2 rows in the bolt_grade section).
• Metric edition note: Fastenal's guide also circulates in an ft-lb edition whose metric clamp loads differ slightly (a different proof-load basis), giving values up to ~3.5% lower than the N-m edition for some sizes. This dataset uses the N-m edition consistently for all metric torque rows, so the section is internally consistent; do not mix editions.
• Not covered: stainless steel, brass, aluminium, socket-head cap screws, prevailing-torque locknuts, hot-dip galvanized (Portland Bolt publishes a separate, higher-K column for HDG), and lubricated/waxed conditions are all outside this section's dry plain-finish basis.

Gaps and exclusions

• 1-12 UNF row: the geometry chart's 1 in UNF row is internally inconsistent (TPI printed as 14 while its pitch diameter matches 12 TPI, and a minor diameter matching neither). The row is recorded as 1-12 UNF with pitch diameter from that chart and the minor diameter (0.9098 in) from the Echo Engineering UNC/UNF chart, as named in the row's source.
• M60 fine: the ISO/R 724 table lists an M60x1.5 fine pitch, but no published tap drill for it was found on an opened chart, so the row is omitted rather than computed.
• Metric secondary sizes (M7, M9, M11, …) and additional fine pitches beyond the commonly designated one per size exist in ISO 261/724 but are not included; the dataset covers the preferred coarse series and the standard fine pitch for each size.
• Inch sizes above 2 in, and UNF above 1-1/2 in, are outside the requested range (published charts continue to 4 in).
• Bolt grades outside the requested list (SAE Grade 1, ASTM A307, A449, F3125 A325M/A490M metric structural grades, ISO classes below 8.8) are not included.