Fellows Corporation CNC Gear Cutting Machines

Fellows 10-4 CNC Gear Shaper

$400,000 – $700,000 Updated 2026-03-17

Key Specifications

Spindle Power

11 kW

Max Workpiece ⌀

254 mm / 10 in

Repeatability

±0.004 mm

max cutter stroke

101 mm / 4 in

max module

6 mm

max face width

101 mm (4 in)

Overview

The Fellows 10-4 is a CNC gear shaping machine produced by Fellows Corporation — the Springfield, Vermont-based gear machine builder that pioneered the gear shaping process in the early 20th century and whose name remains synonymous with gear shaping worldwide. The 10-4 designation indicates a 10-inch (254 mm) maximum workpiece diameter and a 4-inch (101 mm) maximum cutter stroke, placing this machine in the medium-capacity class used extensively for automotive transmission gears, cluster gears, idler gears, and internal ring gears that cannot be hobbed due to obstructions or geometry constraints.

Gear shaping is the dominant process for internal gears, cluster gears with close shoulder spacing, and gears with features adjacent to the gear face that prevent hob approach. The Fellows 10-4 uses a reciprocating cutter spindle carrying a disk-form gear cutter that generates teeth by a rotary-generating motion synchronized with workpiece rotation. The CNC architecture of the 10-4 replaces the older mechanical index and feed gear trains with fully electronic synchronization, enabling rapid changeover between different part numbers by program recall rather than physical gear changes. The stroke rate, feed per stroke, and synchronization ratio are all CNC-programmable.

The machine features a rigid C-frame structure that provides excellent access for part loading and supports automation integration with gantry loaders or robot cells. The cutter spindle runs in precision hydrostatic bearings to damp the reciprocating cutting forces that are characteristic of gear shaping. Fellows machines have traditionally emphasized setup simplicity and robust operation, and the 10-4 continues this tradition with an operator-friendly CNC interface designed for shop floor use without requiring gear-specialist programming skills. The machine supports both internal and external gear shaping, crown shaving preparation, and step gear production.

New Fellows 10-4 CNC gear shapers typically price from $400,000 to $700,000 depending on CNC generation, automation, and tooling package. Fellows machines are widely used in North American automotive supply chains and job shops that handle internal gears and cluster gear programs. Competitors include the Mitsubishi ST25CNC, Liebherr LSE series, and Samputensili SC series gear shapers. The Fellows brand retains strong recognition in North American maintenance and tooling supply channels.

Full Specifications

Parameter	Value
Max Workpiece Diameter	254 mm / 10 in
Max Cutter Stroke	101 mm / 4 in
Max Module	6 mm
Max Face Width	101 mm (4 in)
Cutter Diameter	Up to 127 mm (5 in) disk cutter
Spindle Motor Power	11 kW
Stroke Rate	Up to 1,500 strokes/min
Gear Types	External spur/helical, internal spur/helical, cluster gears, step gears
Synchronization	CNC electronic gearbox (no mechanical index gears)
Cutter Spindle Bearings	Precision hydrostatic
Control System	Fanuc or Siemens CNC (model dependent)
Repeatability	±0.004 mm
Machine Weight	~5,500 kg

Strengths & Limitations

Strengths

Gear shaping is the only practical CNC gear cutting process for internal ring gears and cluster gears with close shoulder spacing — the Fellows 10-4 fills this role that hobbing machines cannot
CNC electronic synchronization replaces mechanical index gears, enabling rapid part number changeover and eliminating the large physical gear inventory required by older Fellows machines
Fellows brand tooling ecosystem is extensive — cutters, arbors, and workholding accessories are available from multiple suppliers globally, keeping consumable sourcing straightforward
C-frame structure and open work zone make robot and gantry loader integration straightforward, supporting automated cell configurations for high-volume automotive part programs

Limitations

Gear shaping is inherently slower than hobbing for external gears that could be hobbed — the reciprocating cutter motion limits stock removal rates compared to continuous hob engagement
The 254 mm maximum diameter limits the 10-4 to smaller gears; larger internal ring gears (automatic transmission rear ring gears, planetary carriers) require the Fellows 20-4 or larger platforms
Reciprocating cutter spindle dynamics require careful damping and maintenance of hydrostatic bearing clearances to sustain accuracy over time — more maintenance-intensive than rotary hobbing spindles

Best For

Automotive transmission manufacturers producing internal ring gears, sun gears, and cluster gears where hobbing is geometrically impossible due to adjacent features or bore constraints Job shops and contract gear manufacturers handling diverse gear programs that include internal gears, stepped gears, and shoulder-constrained parts alongside external gear production Industrial OEMs producing small-to-medium internal gears for pump drives, actuators, planetary reducers, and precision motion control components up to 254 mm diameter

Frequently Asked Questions

01 Why use gear shaping instead of hobbing?

Hobbing is faster and more productive for most external spur and helical gears, but it cannot cut internal gears, and it cannot cut cluster gears or gears with a shoulder close to the gear face that prevents the hob from approaching the full tooth depth. Gear shaping uses a reciprocating disk cutter that enters from the face of the gear and generates teeth by a rotary motion, making internal gear cutting practical and enabling cluster gears with very short distance between gear sections. The Fellows 10-4 is chosen specifically for programs where hobbing is geometrically or mechanically prevented.

02 What is the difference between the Fellows 10-4 and 10-2?

The designation numbers indicate maximum workpiece diameter (10 inches for both) and maximum cutter stroke (4 inches vs. 2 inches respectively). The 10-4 has a longer stroke (101 mm vs. 50 mm), making it capable of cutting gears with wider face widths or deeper cuts in a single pass. The 10-2 is typically used for narrow-face gears where the shorter stroke provides faster stroke rates and higher productivity. For transmission ring gears and wider-face internal gears, the 10-4 is generally the correct choice.

03 Can the Fellows 10-4 cut helical gears?

Yes. Helical gear shaping on the 10-4 requires a helical cutter guide that imparts a controlled rotation to the cutter as it reciprocates, generating the required helix angle in the workpiece. The CNC version synchronizes this motion electronically. Helical shaping is common for internal helical gears in automatic transmissions, where helical tooth engagement reduces noise compared to spur gears. The machine can be configured for helix angles up to approximately 30 degrees for internal helical gear applications.