Machining reference · ISO, ASME and NBS sourced
Verified machining reference data
Every number traced to the standard it came from — formula shown, assumptions stated, dated. Inch and metric on the same row, built to print and laminate.
https://shopmath.org · data verified August 1, 2026
184
Thread sizes
397
Drill sizes
2,250
Verified values
8
Sourced datasets
All values verified August 1, 2026
Machining Reference Tables
One index per entity family. Every page under them carries the standard it came from, its formula and the date it was last checked.
- Screw Thread ReferenceUNC, UNF, UNEF, ISO metric and NPT sizes with tap drills, clearance holes and class limits.
- Drill Size ReferenceNumber, letter, fractional and metric drills — decimal equivalents and what each one taps.
- ISO 286 Fits & TolerancesPer-designation limits, fit pairs and the thirteen verified nominal sizes, in µm and mm.
- Sheet Metal Gauge ReferenceGauge thickness by material — steel, galvanised, aluminium and the 1893 U.S. Standard.
- AS568 O-Ring SizesAll 349 AS568 dash numbers with tolerances, metric equivalents and static gland depths.
- GD&T SymbolsThe fourteen geometric characteristics and eight modifiers — symbol, datum rule and zone shape.
Machining Reference Charts
The head-term tables: complete, server-rendered, and built to print.
- Tap Drill ChartEvery inch and metric thread in one interleaved table, with selectable thread engagement.
- Drill Size ChartNumber, letter, fractional and metric drills in one decimal-equivalent table, sorted by diameter.
- ISO 286 Tolerance ChartIT grades and fundamental deviations across every size band, with limits for each designation.
- Sheet Metal Gauge ChartGauge to thickness for steel, galvanised, aluminium and U.S. Standard — plus millimetres back to gauge.
- AS568 O-Ring Size ChartAll 349 AS568 dash numbers with inside diameter, cross-section and OD in inch and millimetre.
Machining Calculators
For the numbers a printed table cannot hold — any thread engagement, any fit diameter, any measured deviation. Each one shows the formula with your numbers in it.
- Tap Drill Size CalculatorAny of 150 inch and metric threads at any thread engagement from 50% to 100% — with the drill that actually fits and what it really leaves.
- Thread Engagement CalculatorThe reverse: you have a drill in your hand, or a hole already in the part. Find out what percent of thread it leaves before you run the tap.
- ISO 286 Limits & Fits CalculatorHole and shaft limits, clearance or interference, and the tolerance zones drawn to scale — any size from 1 to 500 mm, any letter and grade in the table.
- True Position CalculatorMeasured X/Y deviation to a diametral position value, with MMC or LMC bonus tolerance and the pass/fail against the feature control frame.
- Thread Tensile Stress Area CalculatorTensile stress area from the thread's own geometry, multiplied by the strength off your fastener's spec sheet — never by a number we could not verify.
Screw Thread Series
Most Looked-Up Thread Sizes
What Is In the Verified Database
Every dataset here has passed its validation harness against published tables. Rows without a link are verified data whose pages have not shipped yet — they are listed so the scope of this reference is never a guess.
| Dataset | Values | Standard | Method | Pages |
|---|---|---|---|---|
| Standard drill index — number, letter, fractional, metric | 397 | ANSI/ASME B94.11M; BS 328 | computed+compiled | live |
| ISO 286 IT grades, fundamental deviations and fits | 1,162 | ISO 286-1:2010, ISO 286-2:2010 | compiled | live |
| Sheet-metal gauge thicknesses — steel, galvanized, aluminium, US Standard | 136 | 15 U.S.C. 206; Manufacturers' Standard Gauge; Brown & Sharpe / AWG | computed | live |
| GD&T geometric characteristics and modifiers | 22 | ASME Y14.5 (cited, not reproduced); ISO 1101 | compiled | live |
| SAE AS568 o-ring sizes and gland design | 349 | SAE AS568; MIL-G-5514G (public domain, inactive for new design) | computed+compiled | live |
| ISO metric screw threads — M1.6 to M64, coarse and fine | 68 | ISO 68-1, ISO 261, ISO 262, ISO 965-1, ISO 898-1 | computed+compiled | live |
| NPT and NPTF taper pipe threads | 34 | ASME B1.20.1, ASME B1.20.3; public-domain primary FED-STD-H28/7A (1984) | computed+compiled | live |
| Unified inch screw threads — UNC, UNF, UNEF | 82 | ASME B1.1 (reference values based on the ASME B1.1 system; not a compliance claim) | computed | live |
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