Engineering reference library
The tables we keep open on a second monitor. Written for people who scan real parts, argue about datums, and have to ship a STEP file on Friday.
GD&T Symbol Reference
All 14 geometric characteristics with tolerance zones, when to use them, how they're inspected from scan data, and the mistake each one invites.
Open referenceFits & Tolerances (ISO 286)
Interactive hole-basis fit calculator — H7/g6, H7/p6 and more — with IT grade tables and a guide to picking the right fit.
Open referenceMaterial Properties
Density, yield, tensile, modulus, hardness and machinability for 25 common engineering materials, with typical applications.
Open referenceClearance Holes & Key Sizes
ISO 273 clearance holes, reamer stock allowances, DIN 6885 parallel keys and standard edge-break conventions.
Open referenceScan-to-CAD Glossary
Forty terms every reverse engineer needs — from datum lock and drift to bonus tolerance and the golden tooth.
Open referencePrefer a calculator?
The reference tables above pair with our free tools — surface finish conversion, bolt torque, tap drills, gear geometry, sealing standards and more.
Browse all free tools