Okuma GP-GA26W
Key Specifications
X Travel
Z Travel
max grinding diameter
distance between centers
grinding wheel size
wheel speed max
Overview
The Okuma GP-GA26W is a CNC cylindrical grinder that extends the GA-W series with a longer distance between centers of 1,000 mm (39.4 in) while maintaining the 250 mm (9.8 in) maximum grinding diameter. Where the GA25W handles medium-length shafts, the GA26W is designed for longer workpieces like motor armatures, machine tool spindles, roll shafts, and automotive drivetrain components that need precision OD grinding across a full meter of length.
The grinding wheel is 455 x 75 mm (17.9 x 3.0 in) with a maximum peripheral speed of 45 m/s (8,858 sfm), identical to the GA25W. The wheel spindle uses hydrodynamic bearings for vibration-free operation. The longer table accommodates steady rests for supporting slender shafts during grinding, which is critical for maintaining roundness on long, small-diameter workpieces that would otherwise deflect under grinding forces.
The X-axis (infeed) travel is 250 mm (9.84 in) with a minimum feed increment of 0.0001 mm (0.000004 in). The Z-axis (traverse) travel is 1,050 mm (41.34 in), proportionally longer than the GA25W to accommodate the wider center distance. Rapid traverse rates are 10 m/min (394 ipm) on X and 15 m/min (591 ipm) on Z. The headstock provides workpiece rotation from 10 to 500 RPM with an MT5 center.
The OSP-P300G control handles multi-step traverse grinding sequences across the full 1,000 mm workpiece length, with automatic reversal, dwell, and spark-out programming. Gap elimination sensing and in-process gauging are available. The table swivels +/- 6 degrees for taper grinding along the full workpiece length.
Machine weight is approximately 6,500 kg (14,330 lb). Floor space runs approximately 4,200 x 2,400 mm (165 x 94 in). New pricing typically ranges from $200,000-$280,000. The GP-GA26W competes with the Studer S33/S41, Kellenberger 1000, and Toyoda GE6Pi for long-shaft precision cylindrical grinding.
Full Specifications
| Parameter | Value |
|---|---|
| Max Grinding Diameter | 250 mm (9.8 in) |
| Distance Between Centers | 400 or 650 |
| Grinding Wheel Size | 455 x 75 mm (17.9 x 3.0 in) |
| Wheel Speed Max | 45 m/s (8,858 sfm) |
| X-Axis Travel | 250 mm (9.84 in) |
| Z-Axis Travel | 1,050 mm (41.34 in) |
| Min Feed Increment | 0.0001 mm (0.000004 in) |
| Rapid Traverse X | 10 m/min (394 ipm) |
| Rapid Traverse Z | 15 m/min (591 ipm) |
| Workhead Speed | 10 - 500 RPM |
| Workhead Center | MT5 |
| Swivel Angle | +/- 6° |
| Machine Weight | 6,500 kg (14,330 lb) |
| Floor Space | 4,200 x 2,400 mm (165 x 94 in) |
| CNC Control | Okuma OSP-P300G |
| Max Grinding Dia | Ø200 |
| Grinding Wheel Odxid | Ø610 × Ø254 |
| Max Grinding Wheel Width | 150 |
| Rapid Traversex | 30 |
| Rapid Traversez | 20 |
| Wheel Spindle Motor | 7.5 [15] |
| Okuma Global Repair Center | Charlotte, North Carolina |
| Inches | Metric |
Specifications sourced from okuma.com — verified 2026-03-28
Strengths & Limitations
Strengths
- 1,000 mm between centers accommodates long shafts, spindles, and armatures that won't fit on the shorter GA15W or GA25W platforms
- Same 0.0001 mm infeed resolution and hydrodynamic wheel bearings as the smaller GA models ensure precision is maintained on longer workpieces
- 1,050 mm Z-axis traverse enables full-length traverse grinding of long shafts in a single setup without repositioning
- Steady rest support positions along the longer table prevent workpiece deflection during grinding of slender, long-reach components
- OSP-P300G control handles complex multi-step traverse grinding programs across the full workpiece length with automatic reversal and spark-out
- Same 455 x 75 mm grinding wheel as the GA25W maintains material removal capability while handling longer parts
Limitations
- 4,200 x 2,400 mm footprint is larger than the GA25W, requiring more floor space for what is essentially the same diameter capacity with longer length
- 250 mm maximum grinding diameter is the same as the GA25W; shops needing both longer and larger diameter should look at the GA-F series
- Long workpieces require steady rest setup and careful alignment, adding setup time compared to shorter parts ground on the GA25W
- Single wheelhead configuration means complex multi-diameter long shafts require either multiple plunge positions or slow traverse grinding
- Higher price point than the GA25W reflects the longer bed construction rather than additional capability features
Best For
Frequently Asked Questions
01
New pricing runs $200,000-$280,000 depending on options. The price premium over the GA25W reflects the longer bed, additional Z-axis travel, and heavier machine construction. Steady rests, in-process gauging, and loading automation are the most common options that push pricing toward the upper range.
02
The key difference is length: 1,000 mm between centers vs 650 mm, and 1,050 mm Z-traverse vs 675 mm. Maximum grinding diameter is the same 250 mm on both. If your parts fit within 650 mm, the GA25W is more compact and less expensive. If you're grinding shafts longer than 650 mm, you need the GA26W.
03
For workpieces with high length-to-diameter ratios (typically over 8:1), steady rests are recommended to prevent deflection during grinding. The longer table accommodates one or more steady rest positions. For shorter, stockier parts that happen to need the longer center distance for centering, steady rests may not be needed.
04
Yes. The 1,050 mm Z-axis traverse allows full-length traverse grinding of workpieces up to 1,000 mm between centers. The OSP-P300G control programs automatic traverse cycles with reversal, dwell, and spark-out parameters. Traverse grinding is the standard method for grinding long, uniform-diameter sections on shaft-type parts.
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