Fellows 20-4 CNC Gear Shaping Machine
Key Specifications
maximum workpiece diameter
maximum module
maximum face width
cutter diameter range
stroke rate
cnc axes
How much does the Fellows 20-4 CNC Gear Shaping Machine cost?
Estimated price range
Our best estimate for a cnc gear cutting machine in this class — not a quote from Fellows. Configuration moves it a long way.
Overview
The Fellows 20-4 is a CNC gear shaping machine for workpieces up to 500 mm (19.7 in) in diameter, with a maximum face width of 75 mm (3 in) and a maximum module of 4. The model does not appear on the maker's current pages, so this description relies on the listed figures, which should be checked against the data plate of the machine in question.
The proportions say what the machine is for. A 500 mm diameter capacity paired with a module limit of 4 and 75 mm of face width describes large, narrow, fine-to-medium pitch work: ring gears, internal gears and splined hubs, not coarse-pitch power gearing. Capability is listed as internal and external gears and splines, the territory where a shaper is needed because a shoulder or a blind internal form leaves no room for a hob to run out.
Cutters of 76 – 203 mm (3–8 in) diameter are accepted, helix angles go up to 45°, and stroke rate is up to 1,500 strokes/min. Four CNC axes are listed: X, Y, C for the workpiece and B for the cutter. Gear quality is given as AGMA 9-10. The control row says CNC and names two control makers as alternatives, so identify which one a particular machine carries.
Several things a rigger or tooling engineer needs are missing. The 10-4 lists a 600 lbs. table load and a machine weight of 16,500 lbs.; the listed figures for the 20-4 include neither, nor any motor power, so obtain them before planning fixtures or a foundation.
Full Specifications
| Parameter | Value |
|---|---|
| Maximum Workpiece Diameter | 500 mm (19.7 in) |
| Maximum Module | 4 |
| Maximum Face Width | 75 mm (3 in) |
| Cutter Diameter Range | 76 – 203 mm (3–8 in) |
| Stroke Rate | Up to 1,500 strokes/min |
| CNC Axes | 4 (X, Y, C workpiece, B cutter) |
| Helix Angle | Up to 45° |
| Gear Quality | AGMA 9-10 |
| CNC Control | CNC (Fanuc or Siemens) |
| Capability | Internal and external gears, splines |
Specifications compiled from manufacturer literature and industry references. Not independently verified against a published spec sheet — confirm with the manufacturer or an authorised dealer before making a purchasing decision.
Strengths & Limitations
Strengths
- Workpieces up to 500 mm (19.7 in) in diameter
- Stroke rate of up to 1,500 strokes/min
- Helix angles up to 45° on internal and external gears and splines
- Accepts cutters of 76 – 203 mm (3–8 in) diameter
- Listed gear quality of AGMA 9-10 on four CNC axes
Limitations
- A maximum module of 4 rules out coarse-pitch gears despite the 500 mm (19.7 in) diameter capacity
- Face width is limited to 75 mm (3 in)
- No table load, machine weight or power is listed, unlike the 10-4 with its 600 lbs. table load and 16,500 lbs. weight
- Not shown on the maker's current pages, and the control differs between machines
Best For
Frequently Asked Questions
01
The listed limits are a workpiece diameter of 500 mm (19.7 in), a face width of 75 mm (3 in) and a maximum module of 4. Cutter diameter ranges across 76 – 203 mm (3–8 in). The module limit is the tight one: the machine handles large diameters but not coarse teeth.
02
Yes on both counts, going by the listed figures. Capability covers internal and external gears and splines, and helix angles of up to 45° are listed. The table does not say how the helical motion is generated, so ask whether a given machine needs a dedicated guide for each helix.
03
Gear quality is listed as AGMA 9-10 and stroke rate as up to 1,500 strokes/min. The top stroke rate applies to narrow faces with a short stroke; near the 75 mm (3 in) face width limit the machine will run at a lower rate.
04
The listed figures give the 20-4 a 500 mm (19.7 in) maximum workpiece diameter, while the 10-4 lists a 483mm maximum swing, a 600 lbs. table load and a 16,500 lbs. machine weight. No table load or weight is listed for the 20-4, so a direct comparison of workholding capacity is not possible yet.
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