Setscrew Type Oldham Coupling
GBC6 Series Setscrew Oldham Coupling — aluminium alloy body, zero backlash, high torsional stiffness. Rated torque 0.7–80 N·m, max speed 9,000 rpm, radial misalignment up to 3.8 mm, angular tolerance 3°. 8 sizes (GBC6-16 to GBC6-70), metric and inch bores available. Stocked and shipped Australia-wide by GBC.
GBC6 Series Setscrew Type Oldham Coupling — Zero Backlash, High Torsional Stiffness for Precision Drive Applications
The GBC6 Series Setscrew Type Oldham Coupling is a compact, aluminium alloy three-piece flexible coupling engineered for precision servo, CNC, and encoder drive applications where zero backlash, high torsional stiffness, and the ability to accommodate both parallel and angular shaft misalignment are all required in a single assembly. With rated torque from 0.7 to 80 N·m, maximum speeds up to 9,000 rpm, and radial misalignment compensation up to 3.8 mm, the GBC6 series covers the majority of small-to-medium precision drive coupling requirements encountered in Australian automation, robotics, and motion control applications.
Core Product Parameters at a Glance
Key Features of the GBC6 Series Setscrew Oldham Coupling
Close-tolerance tongue-and-slot interface eliminates lost motion between input and output shafts, making the GBC6 suitable for closed-loop servo positioning and encoder feedback systems.
Static torsional stiffness from 29 to 1,600 N·m/rad across the size range. High stiffness minimises angular lag in servo applications and preserves dynamic positioning accuracy during acceleration and deceleration cycles.
Accommodates up to 3.8 mm radial offset and 3.0° angular misalignment, significantly greater than bellows or disc couplings of similar size, reducing installation precision requirements on motor mounts and bearing housings.
The polymer intermediate disc provides electrical isolation between the two coupled shafts, breaking stray current paths that would otherwise damage encoder bearings, servo motor windings, and adjacent electronic components.
Setscrew (grub screw) hub retention allows rapid installation with a standard hex key. No special tools required. Compact envelope and low mass minimise the reflected inertia seen by servo drives.
Aluminium alloy hubs with natural anodising or optional hard-coat surface treatment resist oxidation and mild chemical exposure, suitable for automation and food-adjacent environments without the weight penalty of stainless steel.
What Is an Oldham Coupling?
An Oldham coupling is a three-piece flexible mechanical coupling designed to transmit rotary motion between two parallel shafts that are laterally offset from one another. The assembly comprises two outer hubs — each bored and fixed to one of the rotating shafts — and a central intermediate disc (the slider) with perpendicular tongue slots on each face that engage corresponding tongues on each hub. As the assembly rotates, the intermediate disc slides within the hub slots to continuously compensate for any radial (parallel) offset between the two shaft centrelines, while transmitting torque with a constant 1:1 velocity ratio.
The engineering problem the Oldham coupling solves is intrinsic to real-world machinery: perfect shaft alignment is rarely achieved or maintained. Motor mount tolerances, thermal expansion, bearing wear, and cumulative assembly variation all introduce some degree of offset between connected shafts. A rigid coupling transmits this offset as a bending moment directly into shaft bearings and seals, accelerating wear and causing premature failure. An Oldham coupling intercepts that offset kinematically at the floating intermediate disc, keeping the lateral force path clean and bearing loads predictable.
What distinguishes the Oldham design from elastomeric couplings — such as jaw or spider-type units — is its essentially rigid torque path and zero-backlash characteristic. There is no elastic element to fatigue, creep, or change stiffness with temperature. The intermediate disc material handles the sliding compensation function without introducing torsional compliance or angular velocity variation. This makes the Oldham coupling the preferred choice wherever precise positioning, constant velocity ratio, and long service life under shaft misalignment are simultaneously required — all of which are standard requirements in Australian servo and automation applications.
How Does the GBC6 Setscrew Oldham Coupling Work?
Each aluminium alloy hub carries a single raised rectangular tongue machined to close tolerances on its face. The intermediate disc carries two perpendicular slots — one on each face — that accept these tongues as a precision sliding fit. When the drive hub rotates, its tongue pushes the disc linearly in one direction. The disc simultaneously slides in the perpendicular direction relative to the driven hub. The net output is pure torque transfer at a constant 1:1 velocity ratio. The centre of the intermediate disc describes a small circular orbit with a diameter equal to the radial offset between the two shaft axes — this is the kinematic compensation mechanism, and it operates continuously and passively throughout every revolution.
For the GBC6 series, radial misalignment compensation ranges from 1.0 mm on the GBC6-16 up to 3.8 mm on the GBC6-63 and GBC6-70 sizes. Angular misalignment tolerance is 3.0° across all eight sizes — a notably high angular tolerance for a zero-backlash coupling, and a feature that significantly reduces the installation precision requirements on motor mounts and gearbox flanges. Maximum operating speeds range from 9,000 rpm (GBC6-16) down to 2,300 rpm (GBC6-70), reflecting the increasing centrifugal loads on the disc orbit as coupling diameter grows.
In servo positioning systems, encoders, and CNC auxiliary drives, the zero-backlash characteristic of the GBC6 is critical. Any elastic windup or lost motion in the torque path appears directly as a positioning error in closed-loop control — a backlash of even 0.1° in a 1:1 drive translates to a measurable position offset at the tool or process point. The GBC6's rigid tongue-and-slot torque path maintains a fixed angular relationship between motor shaft and load shaft, preserving the accuracy of the position feedback loop. The low rotational inertia of the aluminium alloy assembly — as low as 3.0 x 10^-7 kg·m² on the GBC6-16 — also minimises reflected inertia at the servo drive, enabling faster current and velocity loop response times.
Specifications & Material Options
All published dimensional and performance data for the GBC6 series are listed in the tables below. Note that moment of inertia and mass figures are based on the maximum shaft bore for each size. Use this data for initial coupling selection and servo drive inertia calculations; our team can confirm suitability for your specific duty cycle and control architecture.
GBC6 — [Outside Diameter] — [d1 Bore][d2 Bore]
Example: GBC6-25-0810 = GBC6 Series, 25 mm outside diameter, d1 bore 8 mm, d2 bore 10 mm.
The outside diameter determines the frame size. Specify the d1 and d2 bore diameters to match your drive and driven shaft sizes.
GBC6 Series — Dimensions (mm)
| Model | Bore d1, d2 (mm) | OD (mm) | L (mm) | F (mm) | L1 (mm) | M (Setscrew) | Wrench Torque (N·m) |
|---|---|---|---|---|---|---|---|
| GBC6-16 | 4, 5, 6 | 16 | 18 | 3.5 | 7 | M3 | 0.7 |
| GBC6-20 | 6, 6.35, 8 | 20 | 23 | 4.5 | 9 | M4 | 1.7 |
| GBC6-25 | 6.35, 8, 9.525, 10 | 25 | 28 | 5.5 | 11 | M5 | 4.0 |
| GBC6-32 | 8, 9, 9.525, 10, 11, 12, 14 | 32 | 33 | 6.5 | 13 | M6 | 7.0 |
| GBC6-40 | 12, 14, 15, 16 | 40 | 35 | 7.0 | 14 | M6 | 7.0 |
| GBC6-50 | 14, 15, 16, 18, 19, 20 | 50 | 38 | 8.5 | 17 | M8 | 15 |
| GBC6-63 | 16, 18, 19, 20, 24, 25 | 63 | 47 | 10.5 | 21 | M10 | 30 |
| GBC6-70 | 24, 25, 28, 30, 32, 35 | 70 | 59 | 12.5 | 26 | M10 | 32 |
GBC6 Series — Technical Specifications
Note: Moment of inertia and mass figures are based on the maximum shaft bore for each size.
| Model | Rated Torque (N·m) | Max Torque (N·m) | Max Speed (rpm) | Moment of Inertia (kg·m²) | Static Torsional Stiffness (N·m/rad) | Radial Misalignment (mm) | Angular Misalignment (°) | Mass (g) |
|---|---|---|---|---|---|---|---|---|
| GBC6-16 | 0.7 | 1.4 | 9,000 | 3.0 x 10⁻⁷ | 29 | 1.0 | 3.0 | 6 |
| GBC6-20 | 1.6 | 3.2 | 7,400 | 9.0 x 10⁻⁷ | 58 | 1.4 | 3.0 | 14 |
| GBC6-25 | 3.0 | 6 | 5,800 | 2.8 x 10⁻⁶ | 125 | 1.9 | 3.0 | 24 |
| GBC6-32 | 5.5 | 11 | 4,700 | 8.9 x 10⁻⁵ | 260 | 2.4 | 3.0 | 46 |
| GBC6-40 | 9.0 | 18 | 3,600 | 2.1 x 10⁻⁴ | 505 | 2.8 | 3.0 | 80 |
| GBC6-50 | 19.0 | 38 | 3,000 | 6.0 x 10⁻⁵ | 780 | 3.3 | 3.0 | 144 |
| GBC6-63 | 33 | 66 | 2,400 | 2.1 x 10⁻⁴ | 1,200 | 3.8 | 3.0 | 318 |
| GBC6-70 | 80 | 160 | 2,300 | 1.7 x 10⁻⁴ | 1,600 | 3.8 | 3.0 | 456 |
Material Options
The GBC6 series is supplied with aluminium alloy hubs as standard. Aluminium delivers an excellent strength-to-weight ratio, keeping coupling inertia to a minimum — essential for high-speed servo and encoder applications where reflected inertia directly affects drive tuning. Anodising provides corrosion resistance and surface hardness suitable for most industrial environments.
Lightweight and electrically insulating. The standard intermediate disc material for most GBC6 applications. Provides the electrical isolation between drive and driven shafts that protects encoder bearings and servo electronics from stray currents. Self-lubricating properties minimise wear at the tongue-slot interfaces. Suited to the majority of servo and automation operating conditions within the rated temperature range.
Higher rigidity and improved dimensional stability under sustained load compared to nylon. Specified for applications where maximum torsional stiffness is required or where the intermediate disc will be subjected to heavier cyclic loading. Lower moisture absorption than nylon ensures consistent tongue-slot clearance in humid environments. Available on request for GBC6-32 and larger sizes.
Available on request for food processing, pharmaceutical, and marine applications where aluminium alloy is not suitable due to corrosive washdown environments or regulatory requirements. Grade 304 and 316 options available. Stainless steel hubs increase coupling mass and inertia versus aluminium equivalents; confirm servo drive inertia ratio before specifying stainless in high-dynamic applications.
Need a higher torque coupling for your drive application? Browse the complete GBC coupling range, including the WH Type and SL Type Oldham series covering torque requirements from light servo drives through to 63,000 N·m heavy industrial applications.
Industry Applications in Australia
The GBC6 Series Setscrew Oldham Coupling is specified across a broad range of Australian precision motion and automation industries. The combination of zero backlash, high torsional stiffness, generous misalignment tolerance, and compact aluminium alloy construction makes it a default consideration in any servo or CNC coupling selection process.
The GBC6-16 and GBC6-20 sizes are standard choices for direct servo motor shaft to lead screw or linear actuator connections in Australian machine tool, electronics assembly, and industrial robotics applications. Zero backlash preserves positioning accuracy under direction reversal, and low inertia allows servo drives to be tuned to tighter bandwidth.
Spindle encoder coupling and axis servo motor connections on CNC routers, plasma cutters, and machining centres used throughout Australian manufacturing benefit from the GBC6's constant velocity ratio and electrical insulation, which protects encoder electronics from stray currents generated by cutting operations.
Connecting rotary encoders, resolvers, and tachometers to machine shafts is one of the most common GBC6 applications in Australia. The coupling must accommodate minor shaft misalignment without transmitting radial loads into the encoder's delicate bearing, and must not introduce any angular velocity variation that would appear as noise in the feedback signal — both requirements the GBC6 meets by design.
High-speed packaging lines operate servo axes at rates up to 9,000 rpm with frequent directional changes. The GBC6's setscrew fixation allows rapid coupling changes during format changeovers, and its zero-backlash characteristic ensures consistent label placement and fill volume accuracy across all production speeds.
GBC6-16 and GBC6-20 couplings are widely used in Australian-built and imported FDM and SLA 3D printer motion systems where stepper motor shaft to leadscrew connections demand zero backlash, electrical isolation, and accommodation of the minor misalignment common in extruded aluminium frame machines.
Precision pipetting systems, automated laboratory analysers, and medical imaging positioning drives in Australian healthcare and research environments specify the GBC6 series for its compact dimensions, repeatable zero-backlash performance, and electrical isolation properties that protect sensitive electronic measurement systems from electromagnetic interference transmitted through the drive train.
GBC6 Setscrew Oldham Coupling vs Other Coupling Types
The table below compares the GBC6 Series Setscrew Oldham Coupling against three coupling types frequently evaluated alongside it in Australian precision drive and automation procurement.
| Parameter | GBC6 Oldham (Setscrew) | Jaw Coupling | Bellows Coupling | Disc Coupling |
|---|---|---|---|---|
| Parallel Offset Compensation | Excellent (up to 3.8 mm) | Limited (0.1–0.5 mm) | Low (0.1–0.3 mm) | Very Low (<0.1 mm) |
| Angular Misalignment Tolerance | 3.0° (all sizes) | Moderate (1°–2°) | Good (1°–3°) | Low (0.5°–1°) |
| Backlash | Zero | Low–Moderate | Near Zero | Near Zero |
| Electrical Insulation | Yes (polymer disc) | Yes (spider) | No | No |
| Torsional Stiffness | High (29–1,600 N·m/rad) | Low–Moderate (spider material) | Very High | Very High |
| Max Speed | Up to 9,000 rpm | Up to 6,000 rpm | Up to 10,000+ rpm | Up to 10,000+ rpm |
| Installation | Simple — hex key setscrew | Simple — spider accessible | Moderate | More complex |
| Relative Cost | Low–Moderate | Low | High | High |
Why Source Your GBC6 Setscrew Oldham Couplings from GBC Australia?
For procurement engineers and maintenance teams specifying precision couplings in Australian automation, OEM machine building, and servo drive applications, supplier reliability and technical depth matter as much as the product specification itself. Here is why GBC is the supplier of choice for GBC6 series couplings across Australia.
GBC6 Series couplings are produced under an ISO 9001 certified quality management system with documented process controls for precision machining of hub bores, tongue profiles, and setscrew threads. Products comply with RoHS substance restrictions. CE conformity documentation and material test certificates are available for applications requiring formal compliance records.
Custom bore diameters not in the standard table, metric and imperial keyway profiles, alternative intermediate disc materials, stainless steel hubs, and custom surface treatments are all available. Minimum order quantity for custom specifications is 5 pieces. Lead time is typically 7–15 business days from drawing confirmation. For OEM volume requirements, contact us to discuss blanket order pricing and scheduled release programmes.
Our Australian-based technical team responds to all enquiries within one business day. We provide coupling selection assistance (including servo drive inertia ratio calculations), STEP 3D CAD files, dimensional drawings, and installation guidance — all at no charge. Standard GBC6 sizes are stocked for same-week dispatch, supporting both planned build schedules and unplanned breakdown replacement needs.
We supply GBC6 series couplings to customers across all Australian states and territories — NSW, VIC, QLD, WA, SA, TAS, ACT, and NT — via tracked freight. Standard in-stock orders dispatch within 2–3 business days. Standard products in original condition may be returned within 30 days. Custom-specification orders are subject to prior approval for return or exchange.
Ready to confirm your coupling selection or request a sample? Contact the GBC engineering and sales team — we typically respond within one business day with a confirmed recommendation and pricing.
Frequently Asked Questions — GBC6 Series Setscrew Oldham Coupling
Request a Quote or Technical Datasheet for the GBC6 Series Setscrew Oldham Coupling
Tell us your shaft diameters (d1 and d2), required OD frame size, and application torque and speed — we will confirm your bore combination, intermediate disc material, and pricing within one business day.
GBC6 Series Setscrew Oldham Coupling — aluminium alloy body, zero backlash, high torsional stiffness. Rated torque 0.7–80 N·m, max speed 9,000 rpm, radial misalignment up to 3.8 mm, angular tolerance 3°. 8 sizes (GBC6-16 to GBC6-70), metric and inch bores available. Stocked and shipped Australia-wide by GBC.
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