Home > Nema 34 Closed Loop Stepper Motor

86mm Series (NEMA 34) — Closed Loop Stepper Motor

General Specifications

Item	Specifications
Step Angle Accuracy	±5%
Resistance Accuracy	±10%
Inductance Accuracy	±20%
Encoder	1000-line incremental
Temperature Rise	80°C Max.
Ambient Temperature	-20°C ~ +50°C
Insulation Resistance	100MΩ Min. 500VDC
Dielectric Strength	500V AC 1 minute
Allowable Radial Load	0.02mm Max. (450g load)
Allowable Thrust Load	0.08mm Max. (450g load)

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Model	Step Angle (°)	Length (mm)	Voltage (V)	Current (A/phase)	Holding Torque (N・m)	Encoder (line)	Rotor Inertia (g・cm²)	Leads	Weight (kg)
86BYG250-65-CL	1.8	65	1.85	4.4	3	1000	600	4+ENC	1.4
86BYG250-80-CL	1.8	80	2.43	6	5	1000	1000	4+ENC	2
86BYG250-98-CL	1.8	98	3	6	7	1000	1500	4+ENC	2.8
86BYG250-118-CL	1.8	118	2.7	6	8.5	1000	2700	4+ENC	3.8
86BYG250-128-CL	1.8	128	3	6	10	1000	3200	4+ENC
86BYG250-118-CL	1.8	150	3.6	6	12.5	1000	4000	4+ENC

*These are representative models. We can manufacture products according to customer's requirements.

FAQs

What is a closed loop NEMA 34 stepper motor?

A closed loop NEMA 34 stepper motor is an 86mm hybrid stepper with an encoder fitted to the rear shaft. The encoder reports rotor position to a closed loop stepper driver, which corrects following error in real time — so this high-torque frame never loses steps, even under the heavy, swinging loads it usually drives. It runs at a 1.8° step angle (200 steps per revolution).

How is a closed loop NEMA 34 different from an open loop one?

An open-loop NEMA 34 follows step pulses with no feedback and can lose position if overloaded — a real risk on a heavy axis. A closed loop NEMA 34 adds a 1000-line encoder and a closed loop driver, so the system always knows true position and corrects for it. The payoff is no lost steps, lower heating, and a position-error alarm — valuable on a large machine where a stalled axis is costly.

What is the holding torque, step angle, and encoder of your closed loop NEMA 34?

Our closed loop 86BYG250 range runs a 1.8° step angle with a 1000-line incremental encoder. Holding torque runs from about 2.3 N·m on the 67mm body up to 12 N·m on the 118mm body, with rated current 4.0–6.0 A/phase. Full specs are in the table and the downloadable datasheet.

What driver and voltage does a closed loop NEMA 34 need?

A closed loop NEMA 34 needs a closed loop stepper driver that reads the encoder and closes the position loop. Rated current is 4.0–6.0 A/phase, so a high-current driver is needed, and a higher bus voltage (48–80VDC) is recommended on this large frame to hold torque at speed. We supply a matched closed loop driver set up for the motor.

Closed loop stepper or servo for a heavy axis — which should I choose?

On a heavy axis, a closed loop stepper gives no-lost-step reliability with very strong low-speed torque, at lower cost than a servo — a good fit for heavy CNC that runs at moderate speed. A servo wins when the axis must move fast with high dynamic response. See our servo-motors range for that option.

Can you customize the shaft, winding, and lead wires?

Yes. Shaft diameter and length, keyed or dual shaft, lead length and connector, encoder line count, and winding voltage/current are all made to your drawing. A mounting bracket and a planetary or worm gearbox are also available.

Closed Loop NEMA 34 Stepper Motor: Encoder Feedback for Heavy Axes

The closed loop NEMA 34 stepper motor is an 86mm hybrid stepper with an encoder on the rear shaft. The encoder feeds rotor position back to a closed loop stepper driver, which corrects following error in real time — so this high-torque frame never loses a step, even under the heavy, variable loads it usually drives. It keeps the 1.8° step angle and strong low-speed torque of a standard NEMA 34, but adds feedback reliability at a fraction of a servo's cost. A NEMA 34 closed loop stepper motor delivers holding torque from about 2.3 N·m to 12 N·m depending on body length.

Key Specifications at a Glance

Parameter	Specification
Frame Size	86 × 86 mm
Step Angle	1.8° (200 steps/rev)
Type	Closed loop (encoder feedback)
Encoder	1000-line incremental
Holding Torque	2.3–12 N·m
Rated Current	4.0–6.0 A/phase
Body Length	67–118 mm (varies by model)
Shaft	14mm standard

Why Choose Closed Loop on a NEMA 34

On a large, high-torque frame, the cost of a lost step is high — a stalled heavy axis can scrap a part or crash a machine. Closed loop removes that risk while keeping the stepper's strengths:

No lost steps — the encoder catches and corrects following error under heavy load swings.
Lower heating — current is regulated to the load, not held at full value, so a big motor runs much cooler.
Position alarm — the driver flags a fault if error exceeds a limit, important on unattended heavy machines.
Lower cost than a servo — feedback reliability and high torque without servo-level price.

The trade-off versus a servo is top speed and dynamic response; for fast heavy axes, a servo is the better fit.

Typical Applications

The closed loop NEMA 34 suits heavy positioning that can't tolerate a missed step:

Heavy CNC routers and mills — large axes where a lost step ruins the workpiece.
Plasma and laser cutters — big-format gantries needing guaranteed position.
Lathe and machining — feed axes under heavy, varying cutting load.
Heavy automation — large conveyors, lifts, and indexing tables.
Material handling — winders and feeders where position must hold.

With a gearbox the same frame drives an extreme-torque, low-speed axis with feedback intact.

Closed Loop vs Open Loop NEMA 34: Which One Do You Need?

Both are 86mm frames with the same base motor. The difference is feedback:

	Closed Loop NEMA 34	Open Loop NEMA 34
Feedback	1000-line encoder	None
Lost steps	Corrected	Possible under overload
Heating	Lower (regulated current)	Higher (full current)
Cost	Higher	Lower

Pick closed loop when a missed step on a heavy axis is unacceptable or the machine runs unattended. Pick the open-loop NEMA 34 stepper motor when cost leads and the load is steady. Both are 86mm, so they share mounting. For fast heavy axes, consider an AC servo motor.

Customization Options

Cymotorix closed loop NEMA 34 stepper motors can be customized for OEM integration. As a closed loop NEMA 34 stepper motor manufacturer and supplier, we produce them to your specification. Common modifications include:

Shaft diameter and length adjustment (standard shaft is 14mm)
D-cut, flat, or keyed shaft for direct coupling
Encoder line count to suit your resolution needs
Custom lead wire length and connector type
Winding parameters modified to match your driver voltage and current
Dual-shaft output for a second load
Mounting bracket for machine integration
Planetary or worm gearbox integration for higher output torque at low speed

How to Drive a Closed Loop NEMA 34 Stepper Motor

A closed loop NEMA 34 runs on a closed loop stepper driver, which reads the 1000-line encoder and closes the position loop, correcting following error and raising an alarm if error exceeds a set limit. It accepts step/direction pulses like an open-loop system, so it drops into existing controls. Rated current is around 4.0 to 6.0 A/phase, so a high-current driver is needed. We supply a matched closed loop driver set up for the motor if you want the pair tested together.

Recommended supply voltage is 48–80VDC. This large frame has high winding inductance, so a high bus voltage holds torque at speed. Because the driver regulates current to the load, a closed loop motor runs cooler than the same motor driven open-loop at full current.