Sources & Licences

ISO 286 Fits: implemented from Parker Greene’s open-source isofits 1.0 (MIT), validated against ShopMath’s independently cross-checked ISO 286 dataset; ISO 286-1/286-2 is the engineering basis. Release scope: 3–400 mm; s/t/u zones excluded.

GD&T Reference. Original Machinist Companion explanations, diagrams, and first-principles calculations are validated primarily against public NIST GD&T educational publications and ASME public Y14.5 scope/overview material. The copyrighted ASME Y14.5 standard itself is not embedded, reproduced, or used as an app data table.

NBS Handbook H28 — Screw-Thread Standards for Federal Services. U.S. National Bureau of Standards. Primary public technical basis for Unified screw-thread geometry, Unified tap-drill guidance, pipe-thread reference work, and the three-wire measurement method where applicable. Unified Cut Tap Drills: 1969 edition, Part I, Appendix A3 (Table A3.1). NPT Tap Drills: 1957 edition, Part II, Table 7.2 (taper thread, without reamer); where H28 and most published charts disagree, the chart uses the drill most charts use. Three-Wire Acme, Stub Acme and Buttress: 1957 edition, Part III, Sections XII, XIII and XIV (pitch-diameter limits) and Appendix 13 (three-wire methods, including multi-start threads).

Metric cut-tap drills. Derived from the ISO metric thread diameter/pitch relationships and validated against the published drill/tap charts of Purdue University Mechanical Engineering and Walla Walla University.

Drill sizes. Fractional drill diameters are exact mathematical fractions and metric conversions use 25.4 mm per inch. Number and letter drill diameters are checked against public Lawrence Berkeley National Laboratory and other published conversion tables.

ISO 965 metric thread tolerance system. Engineering basis for external metric 6g/6h pitch-diameter limits used by Three-Wire. Current ISO 965-6 covers both 6g and 6h. The app retains published whole-micrometre product-limit values and validates representative sizes against independent thread/gage references.

ThreadBuddy. MIT-licensed clean-room thread calculator. Used as an independent implementation/validation source for inch and metric thread calculations. Its ISO 965 position allowance is useful as a cross-check, but its documented lack of tolerance-band modelling means it is not used as the source of the 6g/6h band width.

Open-source gear references. The Gears & Indexing tools use independently implemented involute spur-gear mathematics cross-checked against FreeCAD Gear Workbench / documentation (GPL-3.0-or-later / CC BY 3.0), BOSL2 (BSD-2-Clause), OpenSCAD MCAD involute gears (LGPL-2.1), Carlos Fernandes' Gear-Calculation project (MIT), and Cogwright (GPL-3.0) for over-pins inspection cross-checks. Tooth depth follows ANSI B6.1, ANSI B6.7, ASA B6.1-1932 (14½° full depth) and ISO 53; standard modules follow ISO 54. The production tools do not copy proprietary gear tables.

tq-threads. MIT-licensed clean-room implementation. Approved candidate for exact listed metric pitch presets, ISO 273 clearance-hole values, ISO 4762 socket-head fastener envelope data, and ISO 10642 countersunk-head envelope data. Approximate/fallback and FDM-specific values are excluded.

bd_warehouse. Apache License 2.0. The inch loose-fit clearance-hole values on the Countersink / Counterbore page are implemented from this project's clearance-hole dataset (pinned commit), with drill designations converted through this site's own drill table; the same dataset independently corroborates the close and normal inch clearance values through 7/16 in. Other columns were reviewed and not adopted. The metric DIN 6885-1 key sizes and keyway depths on the Keyways page (shafts 6–50 mm) come from its shaft-key dataset (pinned commit). Apache attribution is retained in the project notices.

U.S. Army TC 9-524 — Fundamentals of Machine Tools (1996). Approved for public release; distribution is unlimited. Appendix A, Table 8-5 (square and flat keys for shafts 1/2 to 2 in) and Table 8-4 (Woodruff keys No. 204 to No. 1011) are the source of the inch key sizes and Woodruff keyseat depths on the Keyways page. The check dimensions, cutter feeds and hub keyways are calculated from those sizes with the standard ANSI B17.1 / B17.2 relationships, shown in the page's Method & sources. Key sizes outside the open sources' range are not offered until an open source covers them.

GOST 23360-78 — Parallel key connections: key and keyway dimensions, limits and fits. Soviet (now interstate) state standard; its official text is freely published, and Russian law excludes official documents from copyright. Table 2 is the source of the metric key sizes, keyway depths and depth tolerances on the Keyways page for shafts over 50 to 500 mm. The standard corresponds to ISO R773 and has the same sizes as DIN 6885-1; every band from 6 to 500 mm was checked against the ISO R773 / BS 4235-1 table and agrees.

Federal Specification OO-K-220B — Key, Machine (1989). U.S. General Services Administration / Department of the Army; approved for public release, distribution unlimited. Its tolerance table for square machine keys (+0.001/−0.000 in on width and height, 1/16 to 1 in) is the key stock tolerance shown on the Keyways page.

1927 American Standard square and flat stock keys; S.A.E. Woodruff key standard. In the U.S. public domain. The key sizes for shafts 1/2 to 6 in and the Woodruff key and keyseat dimensions (the key's width, diameter, height and height above the shaft, and the keyseat's width and depth, each with its limits) extend the Keyways page.

MIL-G-5514F / G — Gland Design; Packings, Hydraulic, General Requirements For (1969 / 1993). U.S. Department of Defense specification; revision G is approved for public release, distribution unlimited. Table I (O-ring gland dimensions for the MS28775 dash numbers, the AS568 sizes), the surface finishes in 3.2.5, the static-only sizes in 3.5.3 and Figure 3 (suggested face seal gland dimensions) are the source of the inch grooves on the O-Rings page.

GOST 9833-73 — Rubber O-rings for hydraulic and pneumatic equipment: design and dimensions. Soviet (now interstate) state standard; its official text is freely published, and Russian law excludes official documents from copyright. Its ring size tables, the recommended radial and face seats in its appendix, and the appendix's tolerance tables (Table 1, the bore and shaft fits by working pressure; Table 1a, the groove tolerances) are the source of the metric rings, grooves and limits on the O-Rings page. Sizes the standard marks "not recommended" are not offered.

MachineCalcs — Cutting Speed Chart (SFM by Material). CC BY 4.0. https://machinecalcs.com/cutting-speed-chart. Baseline single-point turning cutting speeds for HSS and uncoated carbide.

OpenOregon — Manufacturing Processes 4-5, Unit 2: Speeds, Feeds, and Tapping. Author LamNgeun Virasak. CC BY 4.0. https://openoregon.pressbooks.pub/manufacturingprocesses45/chapter/unit-two-cutting-speed/. General milling cutting-speed table and educational feed-per-tooth guidance.

Wikipedia — Cutting force (machining). CC BY-SA 4.0. https://en.wikipedia.org/wiki/Cutting_force_(machining). Source for the specific-cutting-force (Kienzle model) constants used to estimate cutting force, spindle power, and tool deflection. The article's table is itself compiled from published Sandvik Coromant technical-manual values, not original Wikipedia research. Because this source carries a ShareAlike term, distributing an adapted form of this data may carry its own licence-compatibility obligations; this is noted here for the pending legal review rather than resolved by this page.

Coverage. 15 of 29 selectable materials use the cited Kienzle constants above. 9 materials (brass, copper, bronze, and several nickel/cobalt alloys) use uncited screening-estimate force data pending a citable source, and are flagged in the app as an estimate rather than a cited value. 2 non-metal materials are excluded from the force/deflection model entirely, since polymer and composite cutting mechanics don't fit metal-cutting force theory.

Basic geometry calculators, fractional drill dimensions, RPM/SFM/feed conversions, and other first-principles calculations are generated by Machinist Companion rather than copied from tabular publications.

Release status: the numerical datasets intentionally exposed by the production application are limited to scopes that passed the project’s provenance review. Sources are app-authored, public/government, independently compiled factual data, or open-source/permissively reusable material with required notices retained.

Controlled scope: where a source or engineering method supports only part of a standard or size range, Machinist Companion limits the tool to that supported scope rather than silently extrapolating unsupported values.

Standards references: copyrighted standards may be cited as engineering authority or validation context without embedding or redistributing the standards themselves. Where a tool follows a standard, the dimensional and tolerance values it specifies are used as engineering facts, presented in Machinist Companion's own form.

Engineering accuracy: licensing clearance and engineering validation are separate checks. A reusable source is not automatically treated as authoritative, and calculated or converted values remain subject to the limitations shown in the relevant tool.