A mechanical punch time clock has two things that need to agree on the time: the rotating stamp mechanism that actually prints the time on the time card, and the clock face that employees see when they walk up to punch. These are mechanically independent — you can have one showing the right time while the other is off by an hour. Setting them correctly, and in the right sequence, is the whole job.

This post covers the process for a Lathem mechanical time clock, which follows the same general layout as most mechanical punch clocks from the past several decades.

Getting inside the mechanism

The outer housing has a key-locked cover. Open it with the key — the cover typically slides off once unlocked. Inside you’ll find the clock mechanism, the stamp drum, and the drive motor.

The stamp drum is mounted on a pivot. There’s a locking tab that you press down to release it, which allows the drum to swing outward and then fold flat so you can work on the back of the mechanism. The drum can be a bit unstable in the open position if the clock is wall-mounted — it’ll try to fall back closed. If you’re doing this with the clock off the wall and lying on its back, that’s more stable for adjustment. You can also prop the drum open with something while you work.

The actual time and day settings are on the opposite face of the drum from the stamp surface — the back side. Getting a clear look requires either a light and a small mirror, or just learning by feel.

Setting the day

The day indicator is a small wheel on the mechanism. It advances by spinning in one direction only — there’s a ratchet that prevents it from going backward. Spin it forward until you reach the correct day. The day progression is usually Sunday through Saturday; count carefully if you’re coming from a day that’s several positions away.

Setting the time: hours and minutes independently

The time setting works differently from most clocks. Rather than a single knob that moves both hands together, the Lathem mechanism lets you set hours and minutes independently. There’s a release button — press it to disengage the gear train, which makes the wheels easier to turn. With the release held down, turn the hour wheel until it shows the correct hour, then turn the minute wheel to the correct minute.

Using a small tool (a pencil, a flathead screwdriver, anything that fits) can be easier than using a fingertip, especially if the mechanism is stiff. The wheels are small and the positions can be hard to read clearly.

Verifying the punch time

After setting, close the mechanism back up and punch a test time card. The stamp should print the time you just set. If it’s off, you can open it back up and make a small correction — the mechanism is accessible enough for quick fine-tuning.

The ink ribbon in the stamp mechanism affects print quality. A new ribbon produces a dark, clear impression. A ribbon that’s been in service for a while will produce lighter output. The Lathem on this unit needs a new ribbon, but the punch mechanism is still functioning correctly — you can read the printed time, even if it’s not as dark as it should be.

Setting the display dial

After verifying the punch mechanism is correct, there’s a second adjustment to make: the visible time dial on the front of the clock housing. This is the clock face that employees look at when they walk up.

This wheel is on the exterior of the housing, usually on the side. It also only turns in one direction. Advance it to match the time that the punch mechanism is now stamping. The point is that what the clock shows externally should agree with what it stamps on the card.

These two settings are independent on purpose. Some managers deliberately set the visible dial a few minutes ahead to encourage employees to punch in slightly early. Some set the punch time to give a brief grace period while keeping the visible display on the dot. You can set them to agree, or offset them — that’s a management decision, not a mechanical constraint.

What comes with this unit

This clock comes with a box of blank time cards — close to 500, minus a few used for testing. The standard Lathem card size fits most mechanical punch clocks of this era and is still in production from multiple suppliers. A mounting template and hardware are attached to the back for wall installation.

Lathem and the mechanical time clock business

Lathem has been making time clocks since 1919 — one of the few US manufacturers that survived both the shift from mechanical to electronic timekeeping and later to software-based time and attendance systems. Mechanical punch clocks like this one were the standard for most of the twentieth century, primarily in manufacturing environments where employees weren’t at a fixed workstation with a computer.

The appeal of the mechanical punch clock is its simplicity and tamper-resistance. The time is stamped directly by a mechanical clock mechanism. There’s no software to manipulate, no battery that dies, no app to log into. A working Lathem mechanical clock runs for decades with periodic ribbon and card maintenance.

For small operations — a shop, a warehouse, a construction office — that don’t need the reporting features of modern digital systems, a mechanical punch clock is still a practical tool. They’re not manufactured new at this scale anymore, but the used market has plenty of working units and the supplies (ribbons, time cards) remain available.

References and further reading

• Lathem Time — company website — current product line and support resources, including documentation for older mechanical models
• Time clock — Wikipedia — history of the mechanical punch clock from Bundy Manufacturing through the modern era
• Lathem mechanical clock ribbons — Office supply vendors — compatible ribbon types and where to source them
• Fair Labor Standards Act timekeeping requirements — US DOL — the federal requirements that punch clock records help satisfy