Haas ST-40Y

$190,000 - $245,000 Updated 2026-03-12

Key Specifications

Max Spindle

2,400 RPM

Tool Capacity

12-station BMT-75 turret

Weight

9,525 kg (21,000 lb)

Spindle Power

29.8 kW (40 hp)

max cutting diameter

457 mm (18 in)

max cutting length

711 mm (28 in)

Overview

The Haas ST-40Y is the flagship of the Haas Y-axis turning center lineup. With a 381 mm (15 in) chuck on an A2-8 spindle nose and 102 mm (4.0 in) bar capacity, it is the largest Y-axis lathe Haas builds. This machine handles big, heavy parts that the smaller ST-series machines cannot accommodate.

The spindle delivers 29.8 kW (40 hp) with a max speed of 2,400 RPM. The lower RPM ceiling reflects the larger spindle and chuck mass. Torque is where this machine earns its keep: 542 Nm (400 ft-lb) standard, with an optional gearbox pushing 1,898 Nm (1,400 ft-lb) at 150 RPM. That level of torque lets you take heavy depths of cut on large-diameter forgings, castings, and flanges in tough materials without stalling the spindle.

The ST-40Y uses a BMT-75 turret instead of the BMT-65 found on smaller models. The larger turret provides better rigidity for live tooling operations on bigger parts and handles heavier tool loads. Y-axis travel is 102 mm (4.0 in) total with live tooling at 6,000 RPM and 5.6 kW (7.5 hp). That is more milling power than the 3.7 kW on the smaller ST models, which makes a noticeable difference when cross-drilling and milling on larger workpieces.

Max cutting diameter is 457 mm (18 in) with a cutting length of 711 mm (28 in). The 660 mm (26 in) swing over the cross slide gives you room for large flanges and housings. At approximately 9,525 kg (21,000 lb), the ST-40Y has serious mass for vibration damping and thermal stability.

Priced around $190,000-$245,000 configured, this is Haas's answer to the Mazak QT-400MSY and Okuma LB4000 EX II. The Japanese machines cost $60,000-$100,000 more but offer sub-spindle options and more sophisticated controls. For shops that need large-format Y-axis turning and milling at the most competitive price in the segment, the ST-40Y delivers. Popular in oil and gas, heavy equipment, and aerospace shops running large-diameter turned components with secondary milling features. Specs sourced from Haas Automation published data.

Full Specifications

Parameter	Value
Max Cutting Diameter	457 mm (18 in)
Max Cutting Length	711 mm (28 in)
Max Swing Over Front Apron	914 mm (36 in)
Max Swing Over Cross Slide	660 mm (26 in)
Max Spindle Speed	2,400 RPM
Spindle Motor Power	29.8 kW (40 hp)
Spindle Torque	542 Nm (400 ft-lb) @ 500 RPM
Spindle Torque Optional Gearbox	1,898 Nm (1,400 ft-lb) @ 150 RPM
Spindle Nose	A2-8
Spindle Bore	105 mm (4.13 in)
Chuck Size	381 mm (15 in)
Bar Capacity	102 mm (4.0 in)
X Axis Travel	375 mm (14.75 in)
Y Axis Travel	102 mm (4.0 in) total / ±50.8 mm (±2.0 in)
Z Axis Travel	711 mm (28 in)
Rapid Traverse X Y	12.0 m/min (472 IPM)
Rapid Traverse Z	24.0 m/min (945 IPM)
Tool Capacity	12-station BMT-75 turret
Live Tooling Speed	6,000 RPM
Live Tooling Power	5.6 kW (7.5 hp)
C Axis Positioning	±0.01°
Machine Weight	9,525 kg (21,000 lb)
Coolant Capacity	265 L (70 gal)
CNC Control	Haas Next Generation Control (NGC)

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

Strengths & Limitations

Strengths

15-inch chuck on A2-8 spindle nose securely clamps the largest workpieces in the Haas turning center lineup
BMT-75 turret is larger and more rigid than the BMT-65, handling heavier tooling and more aggressive milling operations
5.6 kW (7.5 hp) live tooling provides 50% more milling power than the smaller ST models for cross-drilling and face milling
Optional gearbox delivers 1,400 ft-lb at 150 RPM for heavy interrupted cuts on large castings, forgings, and flanges
9,525 kg (21,000 lb) machine mass provides outstanding vibration damping and thermal stability
102 mm (4.0 in) bar capacity enables through-spindle work on large-diameter stock
Priced $60-100K below comparable Mazak and Okuma large-format Y-axis turning centers

Limitations

2,400 RPM max spindle speed is the lowest in the ST-Y lineup, limiting surface speed on smaller-diameter work
At $190-245K configured, this is a significant capital investment that approaches Japanese competition pricing
21,000 lb machine weight demands reinforced flooring and professional rigging for installation
No sub-spindle option limits done-in-one capability on parts needing back-working
Large footprint consumes significant shop floor space compared to smaller ST models

Best For

Large-diameter turning of flanges, housings, and heavy components up to 457 mm (18 in) diameter Oil and gas shops machining valve bodies, pipe fittings, and wellhead components with secondary milling features Heavy equipment manufacturers turning large shafts and hubs that need cross-drilling and flat milling Aerospace shops running large titanium and Inconel turned components with off-center features Shops needing the largest Y-axis turning center Haas offers while staying under $250K Production facilities replacing older large-format lathes that want to add Y-axis milling capability

Frequently Asked Questions

01 What does a new Haas ST-40Y cost?

Base price with BMT-75 turret starts around $190,000. Configured with tailstock, chip conveyor, high-pressure coolant, and gearbox, expect $220,000-$245,000. The BMT-75 turret comes standard on the ST-40Y, which is a step up from the BMT-65 on smaller models.

02 Why does the ST-40Y use BMT-75 instead of BMT-65?

The BMT-75 turret uses larger tool stations with more rigid clamping, designed to handle the heavier tooling and greater cutting forces generated when machining larger parts. It also bumps live tooling power to 7.5 hp from 5 hp, which matters for milling on big workpieces.

03 How does the ST-40Y compare to the Mazak QT-400MSY?

The Mazak offers a sub-spindle option, higher spindle speed, and the SmoothG control with more sophisticated mill-turn interpolation. It also costs $60-100K more. The ST-40Y is the value play for shops that need large-format Y-axis turning without a $300K+ price tag.

04 Is the optional gearbox recommended?

For a machine this size, strongly yes. Most shops buying the ST-40Y are turning large-diameter parts in tough materials. The gearbox pushes torque from 400 ft-lb to 1,400 ft-lb at 150 RPM, which is the difference between backing off your depth of cut and taking full-width roughing passes on forgings and castings.

05 What floor requirements does the ST-40Y need?

At 21,000 lb, the machine needs a minimum 6-inch reinforced concrete slab. Haas provides foundation drawings with the machine order. Professional rigging is required for installation, and the machine must be precisely leveled for accuracy.