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THE MACHINEBLUE BOOKResearch · Market · Ownership
DATING A MACHINE

Serial Number and Year-of-Manufacture Lookup Guide

The Machine Blue Book · Published November 2026

Compiled by Bronto, our AI research assistant, from the sources listed below; checked against them and reviewed by our editor before publication. How we make these pages.

Answer: To date a machine tool, find its serial number, then match it against the builder's records or a published serial list. Where the number sits depends on the brand: US Bridgeports carry it on the knee, South Bend lathes on the bed. This guide shows where to look and links the best public tables, brand by brand.

Why does the year of manufacture matter?

The year tells you which design generation you are looking at, which manuals and parts apply, and whether a listing's claims are plausible. A seller's stated year is a claim; the serial number is evidence. Dating by serial lets you check one against the other before you inspect.

Two cautions apply to every table below:

Our short film The Case of the Missing Serial Number walks through the same problem.

How do I date a Bridgeport mill?

Where to look: The Lathes.co.uk Bridgeport serial page states that "The machine Serial Number on US-manufactured examples is stamped into front of the knee casting--not the head." On machines made in the UK by Adcock & Shipley, the same page says "the number should be on a plate inside the column door." [1]

The table: Lathes.co.uk publishes a Bridgeport serial list headed 1938 to 2002 [1]. We link it rather than reproduce it.

Watch for: The page notes that special and modified machines "used a different sequence (and some of these may have been converted back into ordinary types)." [1] The main Bridgeport page adds that on Adcock and Shipley machines badged as Bridgeport, the last four digits of the serial represent the date of manufacture, and that special Model C heads made for Hardinge horizontal millers carry serials beginning with "H." [2] Because heads are often swapped, date the knee, not the head.

How do I date a South Bend lathe?

Where to look: Lathes.co.uk states the serial number is "stamped at the tailstock-end of the bed." [3]

The method: Rather than a lookup table, the Lathes.co.uk page gives an estimating formula: raise the serial number to the power 0.0059 and multiply by 1812. Its worked example, serial 84243, gives about 1937.4 against an actual date of 1938, and the page states "The error appears to be only plus or minus one year or so." [3]

Watch for: On many older lathes, especially those built before the early 1920s, numbers stamped on other parts are "sometimes, but not necessarily, the last three digits of the serial number." [3] The same page says South Bend kept detailed production records that "can quote an exact dispatch date for almost every machine ever made." [3]

How do I date a Hardinge lathe?

The table: Lathes.co.uk's Hardinge page publishes a short list of "Surviving Serial Number records" for the HLV-H (US production) by year, plus a separate HLV list described as "UK production - the only data ever discovered." [4] The HLV-H list has gaps the compiler marks with question marks. Use the link rather than a copy.

Where to look: The page does not state where Hardinge stamps its serials. Check the operator's manual for your model, or contact Hardinge.

How do I date a Monarch lathe?

What is published: Lathes.co.uk's Monarch pages do not include a serial-to-year table. They give dating clues instead: the 10EE was introduced in 1939; early machines made until a change-over that lasted through 1944 and into 1945 are called "old height" models and can be told apart by the round feeds-and-threading selector on the gearbox face; and the first two 10EEs carried serials EE-6156 and EE-6207/8 [5]. For the 10" EC, the page records that the first was sold in 1965 (SN-46637) and the last in 1975 (SN-51301) [6].

Records: The 10EE page states that "the factory has records of every one made." [5] If you need an exact date, that is the source to pursue.

Where to look: The Monarch pages we retrieved do not state where the serial is stamped.

How do I date a Clausing 5900 series lathe?

The table: Lathes.co.uk has a Clausing 5900 Series serial page. It starts with the "First machine: 500200," ends at "512889 (last example built)," and covers a separate 5930 series starting at 530200 [7].

Watch for: The compiler cautions that "it is not know if these represent production numbers at the start or end of the year." [7] (The quotation is reproduced as published.) The page does not state where the serial is located.

How do I date an Atlas 10-inch lathe?

There is no serial table. Lathes.co.uk states that none of the 10-inch lathes "carried date stamps" and that "the only way of discovering when a machine was built is to examine the roller bearings in the headstock," each of which "carries an engraved date marking" if original. Because "front and rear bearings may be some months, or even a year or two apart," the result is approximate [8]. Replaced bearings defeat the method entirely.

What about Haas and other CNC machines?

For modern CNC builders, the builder itself is the authoritative source. The serial number ties to a build record that lists the original options, control software and ship date, which matters more than the year alone.

We tried to cite Haas's own reference documents for this guide, including its machine version identification pages, but haascnc.com refused automated access on November 9, 2026. Until we can cite Haas directly, we publish no Haas serial or year decoding. Contact a Haas Factory Outlet or Haas service with the serial number shown on the machine.

For any CNC machine, ask the seller for a photo of the serial plate and of the control's system or version screen, then ask the builder's service department to confirm the build date and original configuration for that serial. Our machine identity and options guide lists what else to collect.

FAQ

Can I date a machine from a photo of the plate alone? You can make a good estimate for brands with published lists. For a firm date, the builder's records are the only authoritative source.

What if the plate is missing? Look for a stamped number on the casting where the builder put it (the knee on US Bridgeports, the tailstock end of the bed on South Bends). If none exists, date the machine by design features, using the brand's history pages, and treat the result as approximate.

Why do you link tables instead of printing them? The tables are other people's research. Linking keeps them current and credits the compilers.

Is a mismatched head and knee a problem? It is not a defect by itself, but it means the machine's history is mixed. Date and inspect each major component on its own.

Sources

Corrections welcome: research@themachinebluebook.com