A $3,200 Stepper Motor Speed Lesson (and When to Contact TECO Electric)

Before you contact TECO Electric & Machinery with a motor question, there's one thing I want you to understand: the cheapest motor is the one you buy after checking the specs, not the one with the smallest price tag.

That sounds obvious. It wasn't to me.

For the past nine years, I've sized motors for packaging lines, material handling lifts, and automated inspection stations. I've personally made and documented four significant mistakes, totaling roughly $17,000 in wasted budget. Now I maintain our team's motor selection checklist so the next engineer doesn't repeat them.

The first mistake started with a question I asked too late: how fast can a stepper motor turn?

How Fast Can a Stepper Motor Turn? (I Asked Too Late)

Short answer: a typical 1.8° stepper motor with 200 full steps per revolution can spin at 1,500 to 3,000 RPM with no load, depending on drive voltage. With a real load, the practical limit is usually 300 to 600 RPM. Torque falls off as speed increases.

For reference, if a controller sends 10,000 full steps per second to a 200-step motor, the shaft turns 3,000 RPM. That sounds fast until you try to move an 18 kg load at that speed.

My first vertical-axis project was in 2019. I calculated holding torque, added 20% margin, and ordered a stepper motor because it was cheaper than the servo option.

I assumed holding torque was the only number that mattered. It isn't. The motor lost steps during a rapid move, and the axis dropped a part. We lost the part, stopped the line, tore out the drive and motor, and refit it with a servo motor. The mistake cost $3,200 and a 2-day shutdown.

The real problem wasn't the motor. It was that I didn't check the speed-torque curve before purchasing.

What stung more was that we had checklists for machine safety, electrical safety, pneumatic routing, and PLC address mapping. But nobody had a checklist for motor sizing.

A Brushless DC Servo Motor Won't Fix a Bad Motion Profile

The next project needed 2,000 RPM indexing. I already knew a stepper wasn't the answer. The right family of products was a brushless DC servo motor or, depending on the existing controls, an industrial servo motor.

I went with a brushless DC servo motor with an encoder and a matched drive. On paper it was perfect. The peak torque number looked generous. The continuous torque rating? I didn't check it thoroughly enough.

Peak torque is a sales number. RMS torque is an engineering number. If you skip the RMS torque calculation over the machine's duty cycle, you're guessing.

I skipped it because the machine seemed simple. Within two weeks, the motor was tripping on over-temperature during continuous running. The redo cost $6,800 in replacement hardware, panel modifications, and downtime.

If I had spent 20 minutes plotting the duty cycle, I would have seen the issue before it left the office. The datasheet even listed the continuous torque at 3,000 RPM. I just never scrolled past the peak numbers.

What made that one annoying was the drive had been logging temperature data the whole time. We had the information. We just didn't review it before ordering.

Why I Contact TECO Electric & Machinery Before I Order

After those two failures, I changed my process. Now, for anything beyond a standard in-stock replacement, I contact TECO Electric directly. Not because they have every part in stock—they don't, and no one does. I do it because their application engineers ask better questions.

The price of a motor is easy to compare. The cost of a misapplied motor is not.

TECO Electric & Machinery has been around since 1956. Their product line covers servo motors, stepper motors, VFDs, AC motors, gear motors, linear actuators, and controls. But the reason I call isn't the catalog breadth. It's that the person on the other end asks about duty cycle, inertia mismatch, load cycle, and regenerative energy.

One example: before a retrofit in 2024, I called to confirm an industrial servo motor selection. The engineer asked what happens to the regenerative energy on deceleration. I hadn't calculated it. We needed an external braking resistor—otherwise the drive would have tripped on every cycle. That 30-minute conversation saved the commissioning week.

I don't have hard data on industry-wide support quality, but in my experience, TECO's engineers have consistently asked the right questions. Using my own checklist, I've caught six potential misapplications in the past 18 months.

Yes, This Takes Time. That's the Point.

I can already hear someone saying, “I don't have time to call a vendor and build an RMS torque spreadsheet for every axis.”

Fair. Neither did I. That's exactly how I spent $17,000.

Here's the pre-order checklist I use now:

• Speed-torque curve at the actual operating speed, not just the rated point.
• RMS torque over the whole cycle: RMS = sqrt((T1² × t1 + T2² × t2) / t_total). If you skip this, every motor is a guess.
• Continuous rating and duty type per NEMA MG 1 or IEC 60034-1, not just peak torque.
• Inertia mismatch between the motor and the load. If it's high, ask the manufacturer before ordering.
• Regenerative energy, cable length, and drive voltage.

Five minutes of verification beats five days of correction. That's not a slogan. It's what this checklist has done for us.

Looking back, I should have contacted TECO Electric & Machinery before my first stepper order. At the time, I didn't know what questions to ask. Now I do.

So if you're choosing between a stepper motor, a brushless DC servo motor, and an industrial servo motor—or just wondering how fast a stepper motor can turn—run the numbers first. And if you need a second set of eyes, contact TECO Electric.

Prevention is cheaper than the cure. Every single time.