Engineering Resources
Reference tables and charts — the values you keep looking up, one page each. Free, no sign-up.
Tolerancing & GD&T
GD&T Symbol Reference
All 14 geometric controls, modifiers and datum symbols on one page.
Standard Fits Chart (ISO 286)
Clearance, transition and interference fits at common sizes.
ISO 2768 General Tolerances
Linear tolerance classes (fine/medium/coarse) by size range.
IT Tolerance Grades
ISO 286 standard tolerance (IT) values in µm by grade and size.
Fasteners & Joining
Tap & Clearance Drill Chart
Tap drill and clearance hole sizes with tensile areas — metric and UNC.
Bolt Torque Chart
Recommended torque for metric bolts by property class and size.
Bolt Grades & Strength
Proof and ultimate strength for metric classes and SAE grades.
Socket-Head Counterbore
Clearance, counterbore diameter and depth for socket-head cap screws.
O-Ring Sizes (AS568)
Standard AS568 O-ring ID and cross-section dashes.
Materials
Hardness Conversion Chart
Rockwell C, Brinell, Vickers and approximate tensile strength.
Coefficient of Friction
Static and kinetic friction for common material pairs.
Alloy Temper Designations
Aluminium T/H/O tempers and titanium conditions, decoded.
ISO Balance Quality Grades
ISO 21940 / 1940 G grades with typical rotors and permissible eccentricity.
Manufacturing
Surface Finish Chart
Ra to Rq, microinch and ISO N-grade, with typical processes.
Drill Size Chart
Number, letter and fractional drills with decimal inch and mm.
Sheet-Metal Gauge Chart
Steel, aluminium and stainless gauge to thickness (mm & inch).
Snap-Fit Design Data
Permissible strain rules, friction coefficients and the tapered-beam K factor table.
Plastic Part Design Ratios
Rib, boss, draft, screw-boss, hinge and weld-joint numbers, all as ratios to the nominal wall.
Fluids & Thermal
Pipe Schedule (NPS)
Nominal pipe size: OD and Sch 40/80 wall thickness.
Saturated Steam Table
Pressure, enthalpy, latent heat, specific volume and entropy along the saturation line.
Convection Correlations
Nusselt-number correlations for forced and natural convection, with valid ranges.
Gas Properties
R, cp, cv and k for common gases, derived so cp − cv = R holds exactly.
Fuel Properties
Heating values, stoichiometric air/fuel ratio, max CO₂ and CO₂ per kg burnt.
Electrical
AWG Wire Chart
Wire gauge diameter, area, copper resistance and ampacity.
E-Series Resistor Values
Standard E6/E12/E24 preferred values and their tolerances.
Capacitor Dielectrics
C0G/X7R/Y5V characteristics and standard capacitance values.
LED Forward Voltages
Typical Vf by LED colour and wavelength, with drive current.
IP Rating Chart
IEC 60529 ingress protection — solids and liquids digits explained.
SMD Package Sizes
Imperial and metric chip codes with dimensions and power rating.
Logic Level Thresholds
VIH/VIL/VOH/VOL for TTL, LVTTL, CMOS and low-voltage families.
Thermocouple Types
Type K/J/T/E/N/S/R/B ranges, sensitivity and conductor materials.
Aerospace
Marine
Plate Panel Coefficients
Deflection and stress coefficients for a rectangular panel under pressure, both edge conditions.
Pressure & Head Conversion
kPa, bar, psi and metres of sea or fresh water, on one card.
Reference
Reference aids, not a substitute for engineering judgment.