Vintage Starrett Depth Micrometer No. 440-A

Classic Starrett depth mic, ready to go back to work.

This is a vintage L.S. Starrett Co. No. 440-A depth micrometer, made in Athol, Massachusetts. It has a 2½” base and 1” of micrometer travel, with three interchangeable rods so you can reach deeper features while still reading over a 0–1” span on the barrel.

It’s been lightly cleaned, lubricated, and waxed in my shop and checked across the full 1” travel. Action is smooth and readings are consistent to the limit of my shop references.

Likely 1960s–1970s production based on the logo and markings (exact year unknown).

Features

• Starrett No. 440-A depth micrometer
• Head travel: 0–1” per setup
• Base: approx. 2½” wide for stable readings
• Rods: three interchangeable rods with rounded tips
• Swap rods to reach progressively deeper shoulders, slots, and counterbores while still measuring over a 0–1” range
• Graduations: 0.001” on sleeve and thimble
• Crisp knurled thimble and ratchet for controlled feel
• Hardened, ground steel measuring surfaces
• Marked: “The L.S. Starrett Co., Athol, Mass. U.S.A.”

Great for machinists, toolmakers, and anyone setting up mill or lathe work who prefers a depth mic over guessing with calipers.

Condition

Function

• Spindle runs smoothly through the full 1” of travel with no gritty spots.
• Rods seat solidly and thread in/out by hand.
• Reads consistently and repeatably across the range in shop checks.
• Not lab-calibrated; sold as a good, serviceable vintage tool for shop use.

Cosmetics

• Cleaned but not “restored shiny” – original industrial finish with honest shop patina.
• Light staining and minor marks from normal use, especially on the base and barrel.
• Knurling is still sharp and comfortable.
• Engraved markings and graduations are clear and legible.
• No ugly grinder rash or deep pitting that would affect use.

Service performed

• Wiped down with mineral spirits to remove old oil and grime.
• Lightly lubricated with mineral oil, plus a micro-dot of Hoppe’s on threaded parts.
• Thin coat of paste wax on exposed metal, buffed to a dry, low-sheen finish so it feels clean in the hand but has some protection for storage and shipping.

What’s Included

• Vintage Starrett No. 440-A depth micrometer head with 2½” base
• Three rods (one installed, two loose)
• No case, standards, or wrench included
• Printed care guide

What you see in the photos (minus the ruler and backdrop props) is what you get.

Approximate Specs

• Head travel: 0–1”
• Base length: ~2½”
• Rod diameter: ~⅛”
• Graduations: 0.001”
• Material: Hardened steel

Packaging & Shipping

I ship tools the way I like to receive them:

• Rods will be wrapped separately so they can’t bang against the base.
• Mic will be lightly closed, padded, and boxed with plenty of protection.
• Typically ships next business day.