Industrial Tolerances over History

(Created 15 December 2009)
(Revised April 2024)

Era/Item

Tolerances

Reference

1712 – Newcomen Steam Engine Pistons

“They had to be finished to the right size by hand. The achievable tolerance was said to be 'the thickness of a man’s little finger' ” – ½ inches (12,700 microns)

Engineering Timeline (LINK)

1911 – Colt M1911 .45 ACP Slide

0.015 to 0.005 (381 to 127 microns)

M1911 Drawings (LINK)

2020 – F-35 Titanium Tail Fin Parts

0.00118 inches (30 microns)

Fabricating Metalworking (LINK)

1918 – Liberty Engine
1940s – Ford Motor Co. Std. Tolerance

1/1000 inch (0.001) (25.4 microns)

Automotive Industries, Volume 39 (LINK)

Willow Run, Randy Hotton & Michael W.R. Davis; page 97.

1942 – Packard Merlin Supercharger

0.0001 inch (2.54 microns)

Hemmings Motor News (LINK)

1988 – A320 Airliner in Length

12.7mm (0.5± in) over 123 ft (37.49m)

Tolerances in A/C Mfg (LINK)

1989 – B-2 Spirit in Width

2± mm over 172 ft (52.4m)

Tolerances in A/C Mfg (LINK)

2010 – 5-Axis CNC Mill

2± microns

Micron-Tolerance Machining Means Never Looking Back (LINK)