Haas ST-55S

$400,000 - $475,000 Updated 2026-03-19

Key Specifications

Max Spindle

1,000 RPM

Spindle Taper

A1-20 Front & Rear

Tool Capacity

12 Stations

Spindle Power

55.0 hp

swing over front apron

876 mm (34.5 in)

swing over cross slide

648 mm (25.5 in)

Overview

The Haas ST-55S is the sub-spindle variant of the largest turning center in the Haas lineup. It pairs the ST-55's massive 318 mm (12.5 in) spindle bore, A1-20 spindle nose, and 41.0 kW (55 hp) spindle with a secondary spindle for back-working operations on the heaviest large-bore components Haas can handle.

The main spindle drives through a 2-speed gearbox, producing 5,762 Nm (4,250 ft-lb) of torque at 30 RPM. Max spindle speed is 1,000 RPM, reflecting the machine's focus on heavy material removal at low speed on massive workpieces. The cutting envelope is 648 mm (25.5 in) diameter by 2,032 mm (80 in) length. Axis travels are 432 mm (17 in) in X and 2,032 mm (80 in) in Z.

The sub-spindle adds back-working capability that transforms the ST-55 from a heavy turning machine into a complete large-bore manufacturing cell. Pipe couplings, large flanged components, and tubular assemblies that require machined features on both ends can be completed in a single setup, eliminating the accuracy-robbing re-chucking operation that plagues large-bore work.

The 12-station BOT turret is standard. Rapids run at 18.0 m/min (710 ipm) in X and 8.1 m/min (320 ipm) in Z. At approximately 14,969 kg (33,000 lb), the ST-55S is the heaviest machine in the Haas catalog and demands serious foundation preparation.

Starting at approximately $400,000-$475,000 configured, the ST-55S is the ultimate Haas turning investment. For oil and gas, power generation, and heavy industrial manufacturers running high-value large-bore components that demand complete machining in a single setup, the sub-spindle capability pays for itself by eliminating re-chucking errors and second-operation bottlenecks.

Full Specifications

Parameter	Value
Swing Over Front Apron	876 mm (34.5 in)
Swing Over Cross Slide	648 mm (25.5 in)
Max Cutting Diameter	27.50 in
Max Cutting Length	44.0 in
Bar Capacity	318 mm (12.5 in)
Spindle Nose	A1-20 Front & Rear
Spindle Bore	12.50 in
Max Spindle Speed	1,000 RPM
Spindle Motor Power	55.0 hp
Spindle Torque	5,762 Nm (4,250 ft-lb) @ 30 RPM
Spindle Drive	2-Speed Gearbox
Sub Spindle	Yes
X Axis Travel	432 mm (17 in)
Z Axis Travel	2,032 mm (80 in)
Rapid Traverse X	18.0 m/min (710 ipm)
Rapid Traverse Z	8.1 m/min (320 ipm)
Max Thrust X	5500 lbf
Max Thrust Z	9000 lbf
Tool Capacity	12 Stations
Tailstock Taper	MT6
Coolant Capacity	95 gal
Machine Weight	14,969 kg (33,000 lb) approx.
CNC Control	Haas Next Generation Control (NGC)
Capacities	S.A.E
Max Part Swing	35.5 in
Travels	S.A.E
X Axis	20.00 in
Z Axis	44.00 in
Feedrates	S.A.E
Rapids On X	472 ipm
Rapids On Z	710 ipm
Axis Motors	S.A.E
Max Thrust Y	2300 lbf
Spindle	S.A.E
Spindle Taper	A1-20 Front & Rear
Drive System	2-Speed Gearbox
Max Rating	55.0 hp
Max Speed	95 rpm
Max Torque	4250.0 ft-lbf @ 30 rpm
Tailstock	S.A.E
Taper	MT6
Travel	42.0 in
Max Thrust	3,000 lbf
Min Thrust	200 lbf
Turret	S.A.E
Od Vs Id Tools	Any Combination (will vary with turret)
Tooling	BOT
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
Input Ac Voltage Low	220 VAC
Full Load Amps Low	105 A
Input Ac Voltage High	440 VAC
Full Load Amps High	53 A

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

Strengths & Limitations

Strengths

12.5-inch spindle bore with sub-spindle enables complete done-in-one machining of the largest bore components in the Haas lineup
55 hp spindle producing 4,250 ft-lb of torque at 30 RPM delivers massive material removal capability for heavy roughing
80-inch Z-axis travel handles the longest pipe, shaft, and tubular workpieces
Sub-spindle eliminates re-chucking on high-value large-bore parts where concentricity and feature-to-feature accuracy are critical
A1-20 spindle nose with front and rear access enables flexible workholding configurations
Consolidates two operations into one setup, reducing cycle time, handling, and work-in-process inventory

Limitations

1,000 RPM max spindle speed severely limits surface speed on smaller-diameter work — strictly for large, heavy parts
Z-axis rapids at 8.1 m/min (320 ipm) are slow, increasing non-cutting time on long traverses
Machine weight of approximately 33,000 lb demands heavy-duty foundation, specialized rigging, and potential floor reinforcement
At $400K+, this is the most expensive turning center Haas builds — justified only by high-value production

Best For

Oil and gas manufacturers machining large-bore pipe couplings and fittings with features on both ends Power generation shops turning large rotor components, shafts, and housings requiring back-working Mining and heavy equipment manufacturers machining large pins, sleeves, and wear components in a single setup High-value production environments where re-chucking accuracy loss on 12.5-inch bore parts is unacceptable Shops already running ST-55 machines that need sub-spindle capability for higher-value done-in-one work

Frequently Asked Questions

01 What does a new Haas ST-55S cost?

The ST-55S starts at approximately $400,000. With tailstock, chip conveyor, high-pressure coolant, and additional tooling, configured prices reach $440,000-$475,000. The sub-spindle premium over the standard ST-55 is approximately $45,000-$55,000.

02 What is the difference between the ST-55S and ST-55?

The ST-55S adds a sub-spindle for back-working operations. All other specifications — 12.5-inch bore, 55 hp spindle, 4,250 ft-lb torque, 80-inch Z-travel — are identical. The sub-spindle enables complete part machining without re-chucking. Choose the ST-55S when parts require machined features on both ends and production volume justifies the investment.

03 What floor preparation does the ST-55S require?

At approximately 33,000 lb (14,969 kg), the ST-55S is the heaviest machine in the Haas catalog. It requires a minimum 12-inch reinforced concrete floor with rebar, level to within 0.001 inch per foot. Professional rigging with a crane rated well above the machine weight is essential. A Haas HFO site survey is strongly recommended before purchase.

04 Can the ST-55S handle live tooling?

The base ST-55S uses a 12-station BOT turret. For live tooling and milling capability on this platform, check availability with your Haas HFO dealer, as the sub-spindle combined with live tooling creates a comprehensive large-bore manufacturing cell.