FARO CMM Guide: A Maintenance Checklist for Shop and Lab Measurement Equipment

I've been a quality engineer working with metrology equipment for six years. I've personally made (and documented) 14 significant measurement mistakes, totaling roughly $9,800 in wasted budget. This is the checklist I now run before every critical measurement session—especially with a FARO CMM, a tabletop centrifuge, an inductive sensor M12, and a Mitutoyo digital micrometer.

This article is the FARO CMM guide I wish I'd had in 2017: a practical, no-theory checklist for people who need reliable readings on the first try. It starts with the manual, then moves through calibration, environment, and the small details that usually cause failures.

The 7-point pre-measurement checklist

Step 1: Read the FARO guide (and pull out the other manuals too)

I know. Nobody wants to read the manual again. But here's what most people don't realize: the FARO guide for your specific CMM arm (or FARO Gage, if that's what you're using) contains troubleshooting steps that software errors don't explain. In 2019, I spent an afternoon chasing a FARO CMM arm that kept giving inconsistent readings. Turned out the manual had a section on loose interface cables after transport, and it fixed the problem in 30 seconds.

The same applies to the tabletop centrifuge and the inductive sensor M12. The manual tells you the centrifuge's maximum speed and the sensor's rated sensing distance. Put another way: if you're guessing those specs, you're not verifying anything—you're just hoping.

Step 2: Verify calibration status, not just the sticker

This sounds obvious, but “has a calibration certificate” and “is calibrated right now” are two different things. Here's something vendors won't tell you: a calibration certificate only documents the instrument's state at one moment in time. If the device was bumped during transport, the certificate is already stale.

For the FARO CMM, check the calibration date and the service interval. Most FARO CMM arms and laser trackers are on a 12-month cycle. If the last service was under a year ago, it's probably fine. (Should mention: the FARO guide will tell you what the re-verification interval is for your specific model.)

For the tabletop centrifuge, check the speed calibration log. Centrifuges can drift, especially after the rotor is removed and cleaned repeatedly. For the inductive sensor M12, test it against a known metal target—don't assume the LED proves it's detecting at the correct distance.

For formal verification, I use ISO 10360-2 for coordinate measuring machines and IEC 60947-5-2 for inductive proximity sensors. You don't need to memorize the standards, but they're useful when someone argues that a device “should be fine.”

Step 3: Check the environment, not just the instrument

A FARO CMM can read beautifully in the lab and then drift on the factory floor. Temperature changes, vibration, and direct sunlight affect the reading. What was best practice in 2020 may not apply in 2025—portable CMMs are more tolerant than they used to be—but the fundamentals haven't changed: let the instrument stabilize in the room before you measure.

I should add that the same idea applies to a FARO laser tracker: let it warm up and perform its internal compensation if the model requires it.

For the tabletop centrifuge, the environment check is placement. I once put one on a slightly uneven bench and thought, “it's only a quick spin.” The centrifuge vibrated through the whole run, and the pellet quality was inconsistent. (Ugh.)

For the inductive sensor M12 in a fixture, check the cable routing. If the cable runs next to a motor line or a power cable, electrical noise can cause false readings. I've caught 47 potential errors using this checklist in the past 18 months, and six of them were cable-routing problems.

Step 4: How to turn off Mitutoyo digital micrometer (and why you should care)

You'd think this is trivial, but it caused one of my more embarrassing moments.

Most Mitutoyo digital micrometers have a dedicated OFF button. Press it once, and the display turns off. Some models also have auto-off, so they'll shut down after about 20 minutes of inactivity. If the display is frozen and you need to force a shutdown, open the battery compartment and remove the SR44/LR44 battery for about 10 seconds. Reinsert it, and the micrometer should reset.

One thing I learned the hard way: don't change the battery while the micrometer is locked in a measuring stand with the spindle closed. The zero point can shift. Do the battery swap with the measuring faces apart, then close them on a gage block and re-zero if needed.

The FARO CMM shutdown procedure matters too. Don't unplug the controller while the software is still writing a log. Use the normal shutdown sequence. Looking back, I should have read the FARO guide on this earlier. At the time, I thought “it's just powering off a computer.” That one cost me a corrupted file and a redo of a $3,200 order.

Step 5: Use a known reference, not a lucky guess

Before you measure a critical part, verify the instrument against a reference artifact. This is the step I used to skip in my first year.

• FARO CMM arm: measure a calibrated length artifact or a ring gauge if one is available.
• Mitutoyo digital micrometer: close it on a gage block and compare the reading. If it doesn't match, adjust or zero it according to the manual.
• Tabletop centrifuge: verify the actual rotor speed with a non-contact tachometer. Set it to 3,000 RPM and see whether the display matches the real value.
• Inductive sensor M12: place a metal target at the rated sensing distance and confirm the output changes reliably.

In 2017, I skipped the reference check because I was in a hurry: “it was calibrated six months ago, it's the same as last time.” It wasn't. The parts measured 0.2 mm off, the customer caught it, and we ate the cost. That's when I learned that a recent calibration certificate doesn't guarantee today's measurement.

Step 6: Write down the result while you're still standing there

This is the step people skip most. I once checked a FARO CMM's zero point, got a good result, and then got distracted by the phone. Twenty minutes later, I couldn't remember whether I had actually done the check. I did it again, of course, but memory is not a measurement log.

Keep a physical log or a shared digital file. Personally, I prefer a physical log because it's harder to ignore. Record the date, the instrument, the reference used, and the result. If you're in a regulated environment, this log is your audit trail. If you're not, it still saves you from redoing work because you can't remember whether the micrometer was zeroed.

Step 7: Look for the things people ignore

Here are the mistakes I now look for proactively:

• FARO CMM probe condition: a slightly bent probe tip can cause errors that are hard to see during a quick check. If you're measuring tight tolerances, inspect the probe with a magnifier.
• Tabletop centrifuge imbalance: balance tubes by weight, not by eye. I skipped this once because it was a “quick spin.” The noise was unforgettable. So was the failed run.
• Inductive sensor M12 target material: these sensors detect metal, but sensing distance depends on the material. Steel is standard; aluminum behaves differently. Check the datasheet.
• Mitutoyo digital micrometer battery: if the display is dim or flickering, replace the battery before the batch, not in the middle of it. “I'll just finish this measurement first” is exactly what I said before a display died mid-reading.

What usually goes wrong

If I had to narrow it down, the most common thread isn't bad equipment. It's overconfidence in the “minor” steps.

I knew I should have verified the centrifuge speed with a tachometer, but I thought, “what are the odds?” The odds caught up with me when a whole batch of samples had to be redone. That was an $890 mistake plus a one-week delay.

If I could redo that decision, I'd add the reference check to the written checklist and treat it like a nonzero step. But given what I knew then—that the centrifuge had been “working fine” for months—my choice wasn't crazy. It was just wrong.

The industry is changing. FARO and Mitutoyo now offer more software-based checks and connectivity than they did five years ago. Many M12 inductive sensors now have IO-Link diagnostics, and some tabletop centrifuges have self-tests. But the fundamentals haven't changed: a measurement is only as trustworthy as the verification you did before you trusted it.

Print this checklist, adapt it to your lab, and add to it whenever you find a new failure mode. It's not glamorous, but it beats explaining why a FARO CMM, a tabletop centrifuge, and a $40 sensor all failed in the same week.