Star Micronics SB-20RII

$90,000 - $150,000 Updated 2026-03-14

Key Specifications

Max Spindle

Max. 10,000min-1 (OP: Max. 8,000min-1)

Spindle Power

2.2kW (cont)/3.7kW (10min/25%ED)

Max Turn Length

105mm (4-9/64in)

max machining diameter

20 mm (25/32 in), optional 25.4 mm (1 in)

max headstock stroke guide bush

205 mm (8 in)

max headstock stroke non guide bush

Bar diameter x 2.5 (max 50 mm)

Overview

The Star Micronics SB-20RII is the latest evolution of Star's popular SB-20R basic sliding headstock platform, upgraded with enhanced capabilities while maintaining the cost-effective positioning that makes the SB series attractive to shops entering or expanding their Swiss-type turning capacity. With a maximum machining diameter of 20mm (optionally expandable to 25.4mm / 1 inch), the SB-20RII covers the most commercially important diameter range in Swiss-type turning—the range where the majority of medical, automotive, and electronics components fall.

The machine features a 10,000 RPM main spindle with 2.2 kW continuous power (3.7 kW peak), with an optional 8,000 RPM configuration for the larger 25.4mm bar capacity. The sub spindle matches the main at 10,000 RPM but with higher power at 1.5 kW continuous (2.2 kW peak)—a significant upgrade over the smaller SB models' 0.55 kW sub spindles. This improved sub-spindle power enables more aggressive back-working operations including drilling, threading, and contour turning on the back end of parts.

The SB-20RII operates on 7 axes with 6 turning tools (12mm shank) or 5 tools (16mm shank), plus 4-6 sub-spindle stations for back-working. Like all SB-series machines, it features Star's switchable guide bushing system for maximum flexibility—guide bush mode for long parts requiring concentricity, non-guide bush mode for shorter parts to reduce bar remnant waste. The headstock stroke reaches 205mm in guide bush mode.

Running on the modern Fanuc 0i-TF Plus control (an upgrade from the older 0i-TD used on previous SB models), the SB-20RII benefits from improved processing speed and expanded program memory. At approximately 2,000 kg and a footprint of 2,070 x 1,095 mm, it maintains the compact form factor that defines the SB series. The 35 m/min rapid traverse and 180-liter coolant tank support production-oriented operation for shops running multiple shifts.

Full Specifications

Parameter	Value
Max Machining Diameter	20 mm (25/32 in), optional 25.4 mm (1 in)
Max Headstock Stroke Guide Bush	205 mm (8 in)
Max Headstock Stroke Non Guide Bush	Bar diameter x 2.5 (max 50 mm)
Main Spindle Speed	10,000 RPM (8,000 RPM with 25.4mm option)
Main Spindle Power	2.2 kW continuous / 3.7 kW (10 min, 25% ED)
Sub Spindle Speed	10,000 RPM (8,000 RPM with 25.4mm option)
Sub Spindle Power	1.5 kW continuous / 2.2 kW (15 min, 60% ED)
Number Of Axes	7
Turning Tools	6 tools (12 mm) or 5 tools (16 mm)
Sub Spindle Stations	4 standard, expandable to 6
Rapid Feed Rate	35 m/min
Guide Bushing	Switchable (guide bush / non-guide bush)
CNC Control	Fanuc 0i-TF Plus
Coolant Tank	180 L
Machine Weight	Approx. 2,000kg
Dimensions	2,070 x 1,095 x 1,775 mm
Max Turning Diameter	ø20mm (25/32in) OP: ø25.4mm (1in)
Max Turning Length	105mm (4-9/64in)
Bar Capacity	Bar diameter × 2.5 (max. 50mm) (Max. 1-31/32in)
Turret Stations	6 tools (ø12mm) / 5 tools (ø16mm)
Max Spindle Speed	Max. 10,000min-1 (OP: Max. 8,000min-1)
Spindle Motor Power	2.2kW (cont)/3.7kW (10min/25%ED)
Rapid Traverse X	35m/min (X1m Y1, Z1, X2, Z2)
Coolant Capacity	180ℓ
Cnc Control	Fanuc 0i-TF Plus
Floor Space	2,070 × 1,095× 1,775mm
Electrical	4.2KVA

Specifications sourced from starcnc.com — verified 2026-03-28

Strengths & Limitations

Strengths

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Limitations

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Best For

Medical device manufacturers producing bone screws, spinal rods, dental implants, and orthopedic pins in the 10-20mm range Automotive shops running high-volume production of precision shafts, sensor housings, and connector components Contract machining shops seeking an affordable Swiss lathe that handles the most common part diameter range with Star reliability Electronics manufacturers producing connectors, switch components, and precision terminals in production quantities Shops upgrading from older Swiss lathes and wanting modern Fanuc control capability without a premium machine price Hydraulic and pneumatic component manufacturers producing small valve stems, fittings, and precision pistons

Frequently Asked Questions

01 What does a Star Micronics SB-20RII cost?

A new Star SB-20RII typically runs $90,000-$150,000 depending on tooling options, bar feeder, and the 25.4mm bar capacity upgrade. This positions it as one of the more affordable 20mm Swiss lathes from a premium Japanese manufacturer. Used SB-20R series machines trade in the $50,000-$85,000 range.

02 What is new in the SB-20RII compared to the SB-20R?

The SB-20RII features an upgraded Fanuc 0i-TF Plus control (replacing the 0i-TD), improved sub-spindle power at 1.5 kW continuous, expanded sub-spindle station options (4-6 positions), and refined machine construction. The control upgrade provides faster processing, more program memory, and improved operator interface.

03 Should I buy the SB-20RII or the SR-20JII?

The SR-20JII is the better choice for complex parts requiring more axes, more tool positions, Y-axis capability, and advanced control features. The SB-20RII is the better value for shops producing moderately complex parts at high volumes where the extra capability of the SR series is not needed. The price difference can be $50,000-$80,000 or more.

04 Can the SB-20RII machine 1-inch bar stock?

Yes, with the optional 25.4mm bar capacity upgrade. This reduces the maximum spindle speed from 10,000 to 8,000 RPM to accommodate the larger bar, but provides the ability to run 1-inch material—a common bar size in North American shops. This makes the SB-20RII a versatile choice for shops that occasionally need 1-inch capability.

05 What is the guide bush vs non-guide bush trade-off?

Guide bush mode supports the bar stock near the cutting point, providing superior rigidity and concentricity for parts with high length-to-diameter ratios (typically L/D greater than 3:1). Non-guide bush mode eliminates the guide bushing, reducing bar remnant length from typically 300mm to under 50mm, which saves significant material cost on expensive bar stock like titanium. The trade-off is slightly less support for very long, slender parts.

06 How reliable are Star SB-series machines?

Star Micronics has one of the best reliability reputations in the Swiss-type lathe industry. The SB series uses proven mechanical designs with decades of field history. Common maintenance items include guide bush replacement (wear item), spindle bearing service at scheduled intervals, and standard lubrication. Many SB-series machines run 15-20 years in production environments with proper maintenance.