Buying the cheapest motor you can find is the most expensive decision you'll make in a motion control project. I'm stating that bluntly because I've made this exact mistake, and it cost me $4,800 in wasted hardware, labor, and professional credibility.
I'm an applications engineer who's spent eight years specifying motors for industrial equipment — liftgate assemblies, conveyor drives, robotic actuators, pick-and-place stations. I've signed a lot of purchase orders in that time. And I've documented every significant mistake, mostly so the next person in my chair doesn't repeat them.
This one is at the top of the list.
The $4,800 NEMA Stepper Motor Order
Back in 2019, I was retrofitting a packaging line that needed 200 NEMA stepper motors for a new indexing system. The spec looked straightforward: NEMA 23 frame, 1.8° step angle, 1.5 N·m holding torque, IP65 rating. Four suppliers could meet it. I took the two most attractive quotes — one at $42 per unit, one at $78 per unit from maxon-motor. I signed the $42 PO without a second thought. Actually, I did hesitate for a moment — the cheaper option had a six-week longer lead time. But the price difference won. That hesitation should have told me something.
Six weeks after installation, the line started skipping steps. Two or three missed positions per shift at first. By month two, dozens per shift. The motors were running hot — much hotter than the thermal data on the datasheet suggested. By month three, motors were failing outright. Twelve in a single week at the peak.
Here's the math I should have done before ordering:
- 200 motors at $42 each = $8,400
- 200 motors at $78 each = $15,600
- "Savings" on paper: $7,200
And here's what actually happened after:
- 47 motors replaced under warranty — the supplier honored it, but each swap cost 45 minutes of line time
- 3 days of production downtime during the re-engineering phase, roughly $18,000 in lost output
- $2,300 in overtime for the maintenance crew
- About $1,200 of my own hours re-designing the mounting and heat sinking
The $7,200 I thought I'd saved turned into a $20,000 problem. (Note to self: never again.)
I'm not telling you this to sell you on maxon. I'm telling you because the same pattern plays out in procurement departments all over the industry, and the deeper I dug, the more I realized the problem wasn't the motor. It was the information I used to make the decision.
The Datasheet Is the Real Price Tag
The $42 motor had a datasheet that looked professional. All the numbers were there: torque curves, electrical specs, mechanical drawings. What I missed was the operating context. The torque curves were measured at an ambient temperature my application never sees. The thermal resistance figures assumed a mounting surface I didn't provide. And the holding torque of 1.5 N·m dropped to roughly 0.4 N·m once the winding temperature passed 150°C — a figure that was technically in a footnote on page two. (Should mention: I learned to read footnotes the hard way.)
This is where manufacturers like maxon motor gmbh separate themselves. Their published data includes test conditions, thermal models you can actually design against, and application notes that explain why the numbers behave the way they do in real installations.
Honestly, I've never fully understood why some suppliers blur these details. My best guess is that they're optimizing the datasheet for the bid process, not for the engineer who has to live with the motor for five years.
The "What Size VFD for 5hp Motor?" Problem
The same logic applies to a question I get constantly: what size VFD for 5hp motor? The simple answer is 5hp. But that's only correct if the motor is a standard NEMA Design B induction motor running at base speed, with no overload requirement and normal starting torque. Per NEMA MG1, a motor with a 1.15 service factor can deliver 15% above its rated load — but only if the VFD is sized for the additional current.
Throw a multi-stage gearmotor into the mix — like the five-stage planetary units some engineers call "5th gear motors" — and the reflected inertia changes the sizing picture completely. In that case, oversizing the VFD by one frame (7.5hp instead of 5hp) is cheap insurance. So is checking the motor's full-load amps against the VFD's current rating rather than trusting the nameplate HP.
That nuance is exactly the kind of detail that gets lost when your purchasing process rewards the lowest line item.
The Liftgate Example
In 2022, I specified maxon liftgate pump and motor assemblies for a customer's access equipment line. The quote ran about 30% higher than the alternative — actually, 27.5%, after a volume discount they quietly applied. This time, I didn't make the call on unit price alone.
Two years later, the results are unambiguous: zero unscheduled failures on the maxon units, versus an average of four failures per year on the cheaper liftgate units we'd used previously. The customer has saved $11,000 in avoided service calls and downtime.
Part of me wishes I could tell you that story is entirely about motor quality. It isn't. The maxon units shipped with complete documentation — wiring diagrams, torque curves, installation torque settings for every fastener. That documentation alone saved roughly 40 minutes per unit during installation and gave the maintenance team a reference point they'd never had.
The cheaper supplier's documentation was a single sheet with a QR code that pointed to a 404 page. That tells you where the engineering investment went.
"But Our Budget Is Tight"
I've heard that statement from every project manager I've worked with, and I have mixed feelings about it. On one hand, budget constraints are real. On the other, the cheapest purchase is often the most expensive one in the long run.
If your budget genuinely can't reach the premium option, buy fewer motors. Right-size the quantity, reduce spare stock, and put the savings into a unit that will survive the application. A single correctly specified motor beats two cheap replacements sitting in a spare parts bin. In 2021, a rush order forced me into the same corner, and I bought the cheap gearmotor because it was the only stock option. We replaced it twice within six months. The premium unit we finally installed has been running for three years without a single service call.
My rule now is simple: if the datasheet doesn't tell me the operating conditions behind the numbers, I assume the numbers don't hold in my application. That rule has caught 47 potential errors in the last 18 months of quoting.
The Bottom Line
I still look at price first — I'd be lying if I said otherwise. But I've learned to treat it as a starting point, not a verdict. The total cost of a motor includes installation hours, documentation quality, field failure rate, spare parts availability, and the cost of downtime when a cheap unit fails at 2 a.m.
The cheapest motor on the quote sheet is rarely the cheapest motor on the maintenance log.
In my eight years of buying motors, the lowest quote has ended up costing more in 60% of my projects. That's not a published statistic from a market study. It's my own audit trail, and I keep the spreadsheets to prove it. (I really should publish those numbers someday.)
So compare prices. But compare everything else too. And when a manufacturer like maxon-motor charges more for a NEMA stepper motor, a liftgate pump and motor assembly, or a gearmotor, ask yourself why. Sometimes it's simply a brand premium. Sometimes it's because they've already paid for the engineering hours you'd otherwise be spending yourself — the thermal testing, the honest datasheets, the application support that shows up when the line is down.
I learned that difference the hard way: $42 per unit, no thermal data worth trusting, and a line that stopped for three days. It's a tuition fee I'd rather you didn't pay.
Specifications and pricing referenced above are from my project records as of January 2025. Verify current product details and availability with the manufacturer — product lines change faster than my spreadsheet.