Haas ST-40SY

$275,000 - $340,000 Updated 2026-03-19

Key Specifications

Max Spindle

2,400 RPM

Spindle Taper

A2-8

Tool Capacity

12 Stations

Spindle Power

40.0 hp

max part swing

35.5 in

max cutting diameter

27.50 in

Overview

The Haas ST-40SY adds a sub-spindle to the ST-40Y platform, creating a done-in-one large-frame mill-turn machine that can turn, mill, and back-work parts in a single setup. The sub-spindle catches the part after main-spindle operations, flips it, and machines the back side, eliminating the need for a second operation and dramatically improving accuracy on features that reference both ends of the part.

The main spindle delivers 29.8 kW (40 hp) with a max speed of 2,400 RPM on an A2-8 spindle nose. Peak torque is 1,898 Nm (1,400 ft-lb) at 150 RPM through the standard 2-speed gearbox. An optional XP spindle bumps output to 41.0 kW (55 hp) and 2,847 Nm (2,100 ft-lb). The 381 mm (15 in) main chuck and 102 mm (4.0 in) bar capacity handle the full range of large-frame turning work.

The sub-spindle provides part pickup, back-working, and cutoff capability. It enables complete machining of both ends of the workpiece without unclamping and rechucking, maintaining concentricity and positional accuracy that manual flip operations cannot match.

The BMT75 turret provides 12 stations of live tooling at 4,000 RPM with 5.6 kW (7.5 hp) of milling power. The larger BMT75 format is more rigid than the BMT-65 used on smaller models, handling heavier tool loads and more aggressive milling on larger workpieces. Y-axis travel of 102 mm (4.0 in) total enables cross-drilling, milling flats, hexes, and keyways on both the main and sub-spindle sides. C-axis positioning resolves to 0.01 degrees.

At $275,000-$340,000 configured, the ST-40SY is the most capable large-frame turning center Haas builds. It competes with the Mazak QT-400MSY, Doosan Puma 4100MSY, and Okuma LB4000 EX II MSY in shops that need complete part processing on large workpieces. Specs derived from Haas Automation published ST-40 and ST-40Y data.

Full Specifications

Parameter	Value
Max Part Swing	35.5 in
Max Cutting Diameter	27.50 in
Max Cutting Length	28.0 in
Chuck Size	15.0 in
Bar Capacity	4.00 in
Spindle Nose	A2-8
Spindle Bore	4.62 in
Max Spindle Speed	2,400 RPM
Spindle Motor Power	40.0 hp
Spindle Torque	1,898 Nm (1,400 ft-lb) @ 150 RPM
Spindle Drive	2-Speed Gearbox
Xp Spindle Power	41.0 kW (55 hp)
Xp Spindle Torque	2,847 Nm (2,100 ft-lb) @ 150 RPM
Sub Spindle	Yes
X Axis Travel	508 mm (20 in)
Y Axis Travel	102 mm (4.0 in) total / ±50.8 mm (±2.0 in)
Z Axis Travel	1,118 mm (44 in)
Rapid Traverse X	18.0 m/min (710 ipm)
Rapid Traverse Z	18.0 m/min (710 ipm)
Tool Capacity	12 Stations
Live Tooling Speed	4,000 RPM
Live Tooling Power	5.6 kW (7.5 hp)
C Axis Positioning	±0.01°
Coolant Capacity	95 gal
Machine Weight	20400 lb
CNC Control	Haas Next Generation Control (NGC)
Capacities	S.A.E
Travels	S.A.E
X Axis	20.00 in
Y Axis	± 3.0 in
Z Axis	28.00 in
Feedrates	S.A.E
Rapids On X	472 ipm
Rapids On Y	472 ipm
Rapids On Z	710 ipm
Axis Motors	S.A.E
Max Thrust X	5500 lbf
Max Thrust Y	2300 lbf
Max Thrust Z	9000 lbf
Spindle	S.A.E
Spindle Taper	A2-8
Drive System	2-Speed Gearbox
Max Rating	5.0 hp
Max Speed	4000 rpm
Max Torque	2100.0 ft-lbf @ 150 rpm
Xp Option	S.A.E
Input Ac Voltage Low	220 VAC
Full Load Amps Low	70 A
Input Ac Voltage High	440 VAC
Full Load Amps High	35 A
Main Spindle C Axis	S.A.E
Positioning	0.01 °
Brake Diameter	21.5 in
Brake Holding Torque	450 ft-lbf
Control Type	Interpolated Motion and Positioning
Tailstock	S.A.E
Taper	MT5
Travel	26.0 in
Max Thrust	3,000 lbf
Min Thrust	200 lbf
Turret	S.A.E
Od Vs Id Tools	Any Combination (will vary with turret)
Index Time	2 s
Boring Bar Rear Clearance	4.50 in
Tooling	BMT75
Live Tooling	S.A.E
General	S.A.E
Air Requirements	S.A.E
Air Required	4 scfm @ 100 psi
Inline Air Hose	3/8 in
Coupler	3/8 in
Air Pressure Min	80 psi
Electrical Specification	S.A.E
Dimensions Shipping	S.A.E
Domestic Pallet	217.0 in x 95.0 in x 116.0 in
Export Crate	217.0 in x 95.5 in x 120.5 in
Weight Export Crate	22,141 lb

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

Strengths & Limitations

Strengths

Sub-spindle enables done-in-one machining of both part ends, eliminating second-op rechucking and improving accuracy
BMT75 turret with 7.5 hp live tooling and Y-axis provides aggressive milling capability on large workpieces
40 hp main spindle with 1,400 ft-lb of torque handles heavy roughing on large-diameter forgings and castings
Optional XP spindle upgrade to 55 hp and 2,100 ft-lb for demanding material removal applications
Complete part processing in one setup reduces handling, improves concentricity, and eliminates second-op machine time
At $275-340K, undercuts comparable sub-spindle large-frame mill-turn machines from Mazak, Okuma, and Doosan

Limitations

2,400 RPM max spindle speed limits surface speed on smaller-diameter aluminum work
At $275-340K, this is among the most expensive turning centers in the Haas catalog
Sub-spindle programming adds complexity compared to standard two-axis turning
Machine weight of 11,340 kg requires reinforced flooring and professional rigging

Best For

Done-in-one production of large parts requiring machining on both ends with milled features Oil and gas manufacturers producing valve stems, fittings, and connectors that need complete processing Aerospace shops machining large turned components with tight concentricity requirements between both ends Production facilities that want to eliminate second-op lathe or VMC time on large-format parts Shops running medium-to-high volume parts where sub-spindle cycle time savings justify the capital investment

Frequently Asked Questions

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

Base price starts around $275,000. Configured with XP spindle, chip conveyor, high-pressure coolant, and bar feeder, expect $310,000-$340,000. The sub-spindle adds approximately $80,000-$95,000 over the ST-40Y price.

02 What is the difference between the ST-40SY and ST-40Y?

The ST-40SY adds a sub-spindle for part pickup, back-working, and cutoff operations. The ST-40Y uses a tailstock for part support. Choose the ST-40SY when your parts need machining on both ends and you want to eliminate second operations.

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

The Mazak offers higher spindle speeds, the SmoothG control, and more sub-spindle power. It costs $80-120K more. The ST-40SY delivers comparable done-in-one capability at the Haas price point with NGC control familiarity and HFO dealer support.

04 Is sub-spindle programming difficult to learn?

The NGC control handles sub-spindle operations with dedicated M-codes for part transfer, spindle synchronization, and back-working. Operators familiar with standard Haas turning can learn sub-spindle programming in 1-2 weeks. Haas offers HFO training and application support.