Star Micronics SR-38 Type B
Key Specifications
max machining diameter
max headstock stroke rgb
max headstock stroke rmgb
max front ejection length
max part projection
number of axes
Overview
The Star Micronics SR-38 Type B is Star's standard-class large-diameter Swiss-type lathe, designed for precision machining of components up to 38mm (1.5 inches) in diameter. At this size, the SR-38 serves the intersection of Swiss-type precision and conventional turning center capability, handling parts that are too large for 20mm Swiss lathes but benefit from the simultaneous machining, guide bushing support, and single-setup completion that sliding headstock technology provides.
The 10-axis configuration is controlled by a FANUC 31i-B5 control (Type B), delivering the multi-path programming and advanced motion control that complex large-diameter Swiss parts demand. The main spindle produces 7.5 kW continuous (11 kW peak) at up to 7,000 RPM, while the sub spindle matches at 3.7 kW continuous (5.5 kW peak) at 7,000 RPM. The headstock stroke reaches 320mm with revolving guide bush and 288mm with revolving magic guide bush, providing generous machining length for long components.
Tooling is comprehensive for large-diameter work: 5 front stationary turning tools, 2 rear tools with X3 axis control, a back 8-spindle unit, and 4 cross milling tools. The B-axis controlled power-driven tool unit adds angular machining capability with 3 front and 3 rear tools at one position. This combination enables the SR-38 to complete complex parts with angled holes, compound features, and extensive back-end work in a single cycle.
At 4,300 kg and dimensions of 2,740 x 1,315 x 2,120 mm, the SR-38 is a substantial machine with a 253-liter coolant tank and 16.9 kVA power consumption reflecting its heavy-duty cutting capability. The revolving guide bush unit with pneumatic options and Rotary Magic variant provides flexible bar support configurations. This machine serves aerospace, medical, automotive, and oil and gas applications where large-diameter precision and Swiss-type production efficiency converge.
Full Specifications
| Parameter | Value |
|---|---|
| Max Machining Diameter | 38 mm (1-1/2 in) |
| Max Headstock Stroke Rgb | 320 mm |
| Max Headstock Stroke Rmgb | 288 mm |
| Max Front Ejection Length | 150 mm (5-7/8 in) |
| Max Part Projection | 70 mm (2-3/4 in) |
| Number Of Axes | 10 |
| Main Spindle Speed | 7,000 RPM |
| Main Spindle Power | 7.5 kW continuous / 11 kW (10 min, 25% ED) |
| Sub Spindle Speed | 7,000 RPM |
| Sub Spindle Power | 3.7 kW continuous / 5.5 kW (10 min, 40% ED) |
| Front Tools | 5 stationary turning tools |
| Rear Tools | 2 tools (X3 axis control) |
| Back Unit | 8-spindle (8 tools) |
| Cross Milling | 4 tools |
| B Axis | Power-driven tool unit (front 3 + rear 3 tools) |
| Guide Bushing | Revolving guide bush (pneumatic + Rotary Magic options) |
| CNC Control | FANUC 31i-B5 (Type B) |
| Power Consumption | 16.9 kVA |
| Coolant Tank | 253 L |
| Machine Weight | 4,300 kg (9,480 lb) |
| Dimensions | 2,740 x 1,315 x 2,120 mm |
Specifications sourced from starcnc.com — verified 2026-03-28
Strengths & Limitations
Strengths
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Limitations
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Best For
Frequently Asked Questions
01
A new Star SR-38 Type B with FANUC 31i-B5 and B-axis capability typically runs $250,000-$400,000 depending on tooling configuration, bar feeder, and options. The Type A with 31i-B control is available at a lower price point. Used SR-38 machines trade for $130,000-$220,000 depending on age and condition.
02
Both handle 38mm bar stock, but they serve different philosophies. The SR-38 is Star's standard-class 38mm with traditional gang-type tooling and B-axis option. The SX-38 features a 12-axis configuration with slant-bed construction, dual tooling systems (gang + turret), and is designed for higher-complexity parts. The SX-38 costs more but offers greater tooling flexibility.
03
Yes. The revolving magic guide bush (R.M.G.B.) option allows switching between guide bush and non-guide bush modes. In non-guide bush mode, the headstock stroke is reduced to 288mm, but bar remnant waste is significantly reduced. This is valuable when machining expensive materials like titanium where minimizing waste is critical.
04
The 7.5 kW main spindle handles steel, stainless steel, aluminum, brass, titanium alloys, and engineering plastics at 38mm. At this diameter and 7,000 RPM, the machine provides approximately 835 SFM (255 m/min), well above the requirements for most materials. Coolant delivery is critical at this bar size, and the 253-liter tank supports sustained production.
05
The X3 axis provides independent cross-axis control for the 2 rear turning tools, separate from the main X1 axis. This allows simultaneous front and rear turning operations on different diameters, reducing cycle time by performing roughing and finishing operations in parallel. The X3 axis is a key enabler for the SR-38's cycle time optimization.
Videos
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Community Discussions
Community discussion — New machine day! Anybody on here run a star sr-38b ... - Reddit
Community discussion — Micrometer Brands : r/Machinists - Reddit
Community discussion — Micrometer disassembly : r/Machinists - Reddit
Options and configuration advice — benchtop lathe/mill recommendations? : r/Machinists - Reddit
Links to community discussions. Summaries are editorial — visit the original thread for full context.
