Haas ST-28

$70,000 - $100,000 Updated 2026-03-12

Key Specifications

Max Spindle

3,200 RPM

Tool Capacity

12-station BOT

Spindle Power

29.8 kW (40 hp)

max swing

533 mm (21 in)

max cutting diameter

330 mm (13 in)

max cutting length

572 mm (22.5 in)

Overview

The Haas ST-28 is the big-bore variant of the mid-size ST platform, pairing a 102 mm (4 in) bar capacity and 305 mm (12 in) chuck with a 29.8 kW (40 hp) spindle on an A2-8 nose. It occupies the same 533 mm (21 in) swing frame as the ST-20 and ST-25 but with a significantly larger bore and more spindle power, making it the machine of choice for shops running larger-diameter tube, pipe, and bar stock that won't fit through a 3-inch bore.

The spindle puts out 576 Nm (425 ft-lb) of torque at 325 RPM and tops out at 3,200 RPM. That torque figure is nearly double the ST-25 and positions the ST-28 for heavy roughing in carbon steel, alloy steel, and stainless. The 117.3 mm (4.62 in) spindle bore comfortably handles the 4-inch bar capacity with room for collet systems.

Max cutting envelope is 330 mm (13 in) diameter by 572 mm (22.5 in) length. Axis travels are 239 mm (9.4 in) in X — slightly wider than the ST-25's 213 mm to accommodate the larger chuck — and 572 mm (22.5 in) in Z. Rapids hit 24 m/min (945 ipm) on both axes. Maximum thrust forces are 18,238 N (4,100 lbf) in X and 22,686 N (5,100 lbf) in Z.

The 12-station bolt-on turret and 208 L (55 gal) coolant tank are consistent with the rest of the mid-size ST lineup. The NGC control is standard.

At roughly $70,000-$100,000 configured, the ST-28 fills the gap between the ST-25's 3-inch bore and the ST-35's large-frame platform. Shops machining tubular components, pipe fittings, and large-bore parts that require 4-inch bar capacity get it without stepping up to the significantly larger and heavier ST-35 or ST-40. It competes with the Doosan Puma 2600 and Okuma LB3000 EX II in bore capacity while maintaining the Haas price advantage. Specs sourced from Haas Automation published data.

Full Specifications

Parameter	Value
Max Swing	533 mm (21 in)
Max Cutting Diameter	330 mm (13 in)
Max Cutting Length	572 mm (22.5 in)
Chuck Size	305 mm (12 in)
Bar Capacity	102 mm (4 in)
Spindle Nose	A2-8
Spindle Bore	117.3 mm (4.62 in)
Max Spindle Speed	3,200 RPM
Spindle Motor Power	29.8 kW (40 hp)
Spindle Torque	576 Nm (425 ft-lb) @ 325 RPM
X Axis Travel	239 mm (9.4 in)
Z Axis Travel	572 mm (22.5 in)
Rapid Traverse X	24 m/min (945 ipm)
Rapid Traverse Z	24 m/min (945 ipm)
Max Thrust X	18,238 N (4,100 lbf)
Max Thrust Z	22,686 N (5,100 lbf)
Tool Capacity	12-station BOT
Coolant Capacity	208 L (55 gal)
CNC Control	Haas Next Generation Control (NGC)

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

Strengths & Limitations

Strengths

4-inch bar capacity and 4.62-inch spindle bore handle tube, pipe, and large-diameter bar stock that won't fit through the ST-25
40 hp spindle with 425 ft-lb of torque provides nearly double the torque of the ST-25 for heavy roughing in steel and stainless
12-inch chuck provides substantial jaw reach for large-diameter chuck work without stepping up to a 15-inch frame
A2-8 spindle nose accepts a wider range of heavy-duty workholding than the A2-6 on the ST-20/25
Same mid-size frame footprint as the ST-20 and ST-25, keeping floor space requirements manageable
At $70-100K, costs significantly less than the large-frame ST-35 while delivering the same 4-inch bore

Limitations

3,200 RPM max spindle speed is the lowest in the mid-size ST lineup, limiting surface speeds on small-diameter parts
Same 13 x 22.5-inch cutting envelope as the ST-20 and ST-25 despite the larger bore — no gain in cutting reach
No Y-axis option on the base ST-28, so off-center features still require a second operation
40 hp motor draws more power than the ST-25, increasing utility costs for shops not consistently using the extra power
Heavier chuck and larger spindle assembly reduce acceleration compared to the lighter ST-20 platform

Best For

Pipe and tube machining in oil and gas, petrochemical, and process piping applications Production bar work in 3-inch to 4-inch stock that exceeds the ST-25's bore capacity Hydraulic cylinder and valve body manufacturers machining large-bore components Shops needing 4-inch bore capacity without the floor space and weight of the ST-35 or ST-40 frame Heavy roughing applications in carbon steel and alloy steel where 40 hp and 425 ft-lb of torque are needed

Frequently Asked Questions

01 What does a new Haas ST-28 cost?

Base price starts around $70,000. Adding common options like tailstock, chip conveyor, high-pressure coolant, and bar feeder interface pushes the configured price to $85,000-$100,000. Used ST-28 machines from 2018-2022 typically sell in the $45,000-$70,000 range.

02 How does the ST-28 differ from the ST-25?

The ST-28 jumps from a 3-inch to 4-inch bar capacity, from A2-6 to A2-8 spindle nose, from 30 hp to 40 hp, and from an 8.3-inch to 12-inch chuck. The cutting envelope stays the same at 13 x 22.5 inches. Choose the ST-28 when your bar stock or tube work exceeds 3 inches and you need the extra power and bore.

03 Should I buy the ST-28 or the ST-35?

Both offer 4-inch bar capacity and 40 hp. The ST-35 adds a larger 15 x 32.5-inch cutting envelope, 806 mm swing, and heavier casting. The ST-28 keeps the smaller mid-size footprint. If your parts fit within 13 x 22.5 inches, the ST-28 saves floor space and cost. If you need the larger work envelope, the ST-35 is the right choice.

04 Is the ST-28 suitable for pipe threading?

Yes. The 4-inch bar capacity, A2-8 spindle nose, and 12-inch chuck make it well-suited for pipe threading, facing, and OD turning on standard pipe sizes. The NGC control supports standard and custom thread cycles. For pipe work exceeding the 13-inch max cutting diameter or 22.5-inch length, step up to the ST-35 or ST-40.