FARO Arm Measuring Tool vs. CMM Machines: A Buyer's Comparison (and a Pipette Calibration Lesson)

Why I'm Comparing These at All

I'm the office administrator for a 150-person manufacturing company. That title makes it sound like I order pens and manage the breakroom. I do those things, but I also handle purchasing for our metrology and lab equipment—roughly $350k a year across 12 vendors, including calibration services.

When I took over purchasing in 2020, our metrology lab had one traditional CMM machine, and we were renting portable measurement equipment far too often. In 2024, I ran a formal evaluation of whether to buy a FARO arm measuring tool, add another fixed CMM, or just keep renting. I went back and forth between the fixed and the portable for about two weeks. The fixed CMM felt like the 'safe' choice; the FARO arm felt like the flexible one. Ultimately, we ended up with both—but not in the way you'd expect.

How I Compared the Two

I evaluated four dimensions: spec-sheet accuracy, portability, cost of ownership, and calibration/service. I also looked at hiring and training, because that's often where the real cost hides. Each section below shows the FARO option vs. the traditional fixed CMM.

I'll say up front: I'm not a metrology engineer. I'm a buyer who's had to justify every dollar to the operations budget. If you need a textbook metrology comparison, go to the standards documents. If you need a practical one, read on.

Accuracy: The Fixed CMM Wins (On Paper)

On the first dimension, the fixed CMM wins, and I'll tell you why. A traditional bridge-style CMM sits in a temperature-controlled room on a granite base. It gives you better volumetric accuracy than a portable arm measuring tool. The FARO arm in our lab has a published accuracy around ±0.025 mm, which is fine for most of our parts, but the old CMM's spec is tighter. If we're qualifying a tight bore tolerance, we still use the CMM.

But here's the catch: those accuracy specs only apply within a limited measuring volume. If a part is two meters long, it won't physically fit on the CMM table. A FARO arm can measure it right next to production. The real mistake is fixating on the spec sheet and forgetting the question: can I actually get the part to the instrument? That mismatch is why we kept the CMM and bought the FARO arm.

Portability and Flexibility: No Contest

This is where the portable systems shine. The FARO arm measuring tool travels. You can carry one out to the assembly floor, mount it for a quick surface check, or pack it in a flight case and ship it. The laser tracker is even more capable for large-scale jobs—think aerospace jigs, turbine frames, or process equipment.

We don't own a laser tracker. Instead, we hire contractors for the seasonal FARO laser tracker jobs that show up in Q3 every year, when a big customer asks us to verify tooling before a production run. The contractor sends a technician with a tracker, and we book time on our schedule. (Note to self: reserve them earlier this year—the good ones book out six weeks.) No fixed CMM could do that. If we'd only bought another stationary CMM, we would still be renting.

Cost of Ownership: Not the Price Tag, the Total Spend

Honestly, I'm not sure whether the prices I'm about to share are typical or a quirk of our region. My best guess is they're representative, but verify current quotes. Based on vendor quotes we received in early 2025, a basic FARO arm runs roughly $40k–$70k depending on working volume and options. A fixed CMM with similar repeatability starts around $75k and can pass $150k once you add installation, vibration isolation, and a climate-controlled room. The FARO arm doesn't need that room.

But here's what I didn't account for the first time: support contracts. Looking back, I should have pushed for a better service plan. When we bought the arm, I negotiated the hardware price but skipped the extended warranty because it seemed expensive. Six months later, the arm spent three weeks at service for a probe bracket repair. The repair invoice was four times the contract price I'd declined. That one hurt.

Calibration and Service: A Shared Weakness (Including Pipettes)

Calibration is where I have opinions. I've seen both a CMM and a pipette fail an audit because nobody had a proper schedule.

We didn't have a formal calibration process for the CMM at first. I found out during a customer audit in 2023, when the auditor asked for the latest certificate and I realized it had expired. Cost us a frantic night and an after-hours repair. The third time I had to chase a calibration vendor, I finally created a spreadsheet that flags everything six weeks out. I should have done that years ago.

The same thing applies to pipette calibration in our lab. We have a rack of Eppendorf pipettes, and they're just as easy to ignore as a CMM. I'll admit: I've never fully understood why pipette calibration schedules seem so inconsistent across labs. My best guess is that it comes down to balancing usage-based wear against downtime cost. But we had to define a policy for ourselves. Based on ISO 8655 guidance and the manufacturer's service kit recommendations, we now verify the pipettes every 6 to 12 months depending on how heavily they're used. It's not as hard as people think.

And for new temps, I schedule a short hands-on session that covers how to use an Eppendorf pipette correctly. Yes, trained lab people find it obvious, but the pre-wetting step is forgotten more often than you'd think. Bad technique turns a calibrated pipette into an incorrect volume dispenser. (I really should add a visual checklist on the bench—our last temp thanked me for the verbal one.)

Skills and Hiring: Fixed CMM or FARO Arm?

The skills part almost pushed us to skip the FARO arm. It's easy to imagine 'portable = easy,' but it isn't. You still need people who understand alignment, coordinate systems, and part datums. We hired a temporary metrology technician in 2024, and I had to untangle a week's worth of bad measurement results caused by a misaligned arm base. (Note to self: always require initial setup verification from the tech.)

What about the seasonal FARO laser tracker jobs? That's a niche skill. It is genuinely hard to hire someone who can run a laser tracker for three weeks and then go back to normal QC. We decided not to staff for that. Instead, we use a qualified contractor and send our internal guy to watch—that's how we'll eventually build the skill in-house. The traditional fixed CMM, by comparison, has a deeper labor pool; you can find CMM operators more easily. But programming a CMM well is arguably a longer skill ramp.

Conclusion: Which Should You Choose?

If your world is small, precision-machined parts in a temperature-stable room, a decent fixed CMM machine is the workhorse. Don't let anyone convince you it's obsolete. It isn't.

If you regularly measure large parts, work on the shop floor, or need to take measurements to the part instead of the part to the instrument, a FARO arm measuring tool is very likely the better buy. And if you're looking at multi-meter scale jobs, a laser tracker is a specialist tool. Don't buy one unless the work is steady and you have a trained operator; otherwise, renting or contracting those seasonal FARO laser tracker jobs makes financial sense.

And for the lab side: your Eppendorf pipettes need a calibration schedule, and your staff needs practical training on how to use an Eppendorf pipette. Calibration is not a one-time event. Neither is training. The most expensive measurement error I've managed didn't come from a bad instrument—it came from a process gap and an instrument that hadn't been checked.