Holes and threads
- Tap drill chart: the drill for UNC and UNF threads from #0 to 1-1/2 in and metric threads from M1.6 to M30, the thread percentage it leaves and close and free clearance drills. A 1/4-20 tap takes a #7 drill.
- Drill bit size chart: fractional, number, letter and metric drills with decimal inch and mm, #80 to 1 in.
- Thread pitch chart: UNC, UNF and UNEF threads per inch from #0 to 2 in, and ISO metric coarse and fine pitches from M1 to M36.
Fasteners and seals
- Metric bolt size chart: pitch, hex wrench size (ISO and DIN), socket head key size and ISO 273 clearance holes, M3 to M30.
- O-ring size chart: the 349 standard AS568 sizes from -001 to -475, with actual ID, cross-section and tolerances in inches and mm.
Cutting
- Speeds and feeds calculator: RPM and feed rate from surface speed, flutes and chip load, with starting drilling speeds for HSS and carbide by material.
Where the numbers come from
Inch thread series come from ASME B1.1 as published in NBS Handbook H28, and metric pitches from ISO 261 and ISO 262. Metric bolt dimensions come from ISO 4014, 4017, 4762 and 273, read from the identical Indian Standard adoptions that law.resource.org publishes. Number and letter drill decimals come from Kennametal's decimal equivalency chart, and O-ring sizes from the Parker O-Ring Handbook. Each table lists at least two independent published charts it was checked against, with every difference found. The methodology page explains the checks.