Engineering reference
A free set of engineering reference tools — ask each one a question and get the answer, cited to the governing standard. No ads, no sign-up. Twenty-three tools cover ISO 286 fits and limits, thread data, GD&T and weld symbols, materials and coatings, insert decoding, fastener seats, machine elements, ISO 2768 general tolerances, surface finish, tap drill sizing, keyways, and ASTM E140 hardness — alongside ten machining calculators for true position, tolerance stacks, bolt circles, triangles, and sine bars.
These tools run on the same standards engines behind ASdrawn’s AS9102 FAIR automation. The governing standard text remains authoritative for inspection decisions.
ISO 286-1 / -2
Fits & limits calculator
Hole/shaft limit deviations and the resulting clearance, transition, or interference fit — computed from ISO 286.
60° thread form
Tap drill calculator
Tap drill diameter for any thread and percent engagement, straight from the 60° thread-form formula.
ASTM E140
Hardness conversion
Approximate conversions between Rockwell C, Vickers, Brinell, and tensile strength using ASTM E140 methodology.
ISO 261 / 965 · ASME B1.1
Thread data & callout resolver
Limit dimensions, classes, and tap drills for metric, Unified, and pipe threads, plus a drawing-callout resolver.
DIN 6885-1 / ISO R773
Keyway & key sizes
Parallel key width and height, plus shaft and hub keyseat depths, by shaft diameter.
ISO 2768 / DIN 7168
General tolerances (ISO 2768)
The ± band for any untoleranced dimension by class and feature type, from ISO 2768 (and DIN 7168).
ISO 1302 / 4287
Surface finish (Ra)
The N1–N12 Ra grade series in µm and µin, achievable processes, and ISO 1302 lay symbols.
ASME Y14.5 · ISO 1101
GD&T symbols & modifiers
Geometric characteristic symbols with datum requirements, material-condition modifiers, and ASME↔ISO equivalents.
AMS / ASTM
Materials & coatings lookup
AMS and ASTM material specs with a superseded-spec resolver, plus common coating and plating callouts.
ISO 1832 / ISO 5608
Insert & holder decoder
Type CNMG 120408 and get every field decoded — insert shape, clearance, tolerance, size — plus ISO 5608 holders.
ASME B18.2.8 / B18.3
Counterbore, countersink & clearance
Counterbore, countersink, and clearance hole dimensions by fastener size, for socket head cap screws and more.
ASME B18.8.2 · AS568
Machine elements
Dowel pin sizes, AS568 O-ring groove dimensions, and shaft/housing bearing fit recommendations.
AWS A2.4 / ISO 2553
Weld symbol reference
Weld symbols with names and typical usage — fillet, groove, plug, spot — as they appear on fabrication drawings.
TP = 2·√(ΔX² + ΔY²)
True position calculator
Ø position from X/Y deviations — with MMC/LMC bonus tolerance and a pass/fail verdict against the frame.
Worst-case · RSS
Tolerance stack-up calculator
Worst-case and RSS totals over a chain of dimension contributions, with each contributor listed.
3-wire method
Thread measuring wires
Best wire size and measurement over wires for 60° threads by the 3-wire method.
x = R·cos θ, y = R·sin θ
Bolt circle calculator
X/Y coordinates for every hole in a bolt-circle pattern, from diameter, count, and start angle.
R = (c² + 4h²) / 8h
Chord, arc & radius calculator
Radius from a chord and height, circle through 3 points, arc length and included angle.
H = L·sin θ
Sine bar calculator
Gauge block stack height for an angle on a sine bar or plate — and the angle from a measured stack.
Law of sines / cosines
Triangle solver
Right and oblique triangles from any valid combination of sides and angles — SSS, SAS, ASA, SSA.
m = ρ·V
Stock weight calculator
Bar, tube, plate, and ring weight from dimensions and material density — metric and imperial.
SI ↔ inch
Machinist unit converter
Length, angle (DMS), temperature, pressure, torque, force, speed, mass, and roughness conversions.
deg / rad
Scientific calculator
Keyboard-first expression calculator with trig in degrees or radians.