Haas ST-20Y

Identity and model scope

The Haas comparison lists 2.5 in bar capacity and 22.5 in cutting length for the redesigned ST-20Y, versus 2.0 in and 21 in for the previous configuration. Cutting length depends on workholding. The 2021 flyer lists 12 driven-tool positions even with optional indexing to 24 total positions. The optional A2-5 finishing sub-spindle requires BMT65 and excludes the tailstock. The APL loads and unloads only the main spindle. Verify generation, turret, transfer grip and tool access for the installed setup. Haas ST-20Y comparison, 2021 flyer, A2-5 option.

Haas lists ST-20Y separately from the long-bed ST-20LY and ST-25Y. Haas ST-series catalog.

See Machine configuration references for the asset details to verify.

Generations and capacity terminology

Haas's ST-20Y product page compares a redesigned ST-20 series with a previous model. Its comparison gives bar capacity as 2.5 in, 63.5 mm, versus 2.0 in, 51 mm. Cutting length changes from 21 in, 533 mm, to 22.5 in, 572 mm, with workholding dependence. The table includes both BOT and BMT65 turret rows. The BOT diameter is not the ST-20Y's BMT65 cutting diameter. No serial-number changeover is established here. Haas ST-20Y, specification comparison, official legacy page

The July 2021 Y-axis flyer identifies the ST-20Y with an 8.3 in, 210 mm, chuck, a maximum capacity of 11.75 × 22.5 in, 298 × 572 mm, and 2.5 in, 63.5 mm, bar capacity. Its family description gives Y travel of ±2 in, ±51 mm, about centerline. These are source-stated nominal values, not a promise that all maximum dimensions are usable together. Haas Complete Y-Axis Turning, 39-20004B, PDF page 2

The ST-20Y/25Y layout drawing separates BMT tool clearances, tailstock and sub-spindle layouts, and the Y-axis envelope. It is revision 1, dated 1 April 2019, despite the 2020-11 filename. Its specific tooling layouts are evidence of geometry dependence, not a current universal installation drawing. Haas ST-20Y/25Y layout, PDF pages 4–5

Turning, live tooling, and C-axis motion

The terms describe different functions. Turning removes material from a rotating workpiece with a cutting tool. Live tooling drives the tool itself. Haas's lathe manual describes axial and radial live tools for milling, drilling, and slotting. Its Y axis moves tools perpendicular to the spindle centerline through compound motion. The C axis controls bidirectional spindle motion interpolated with X or Z; its suitability depends on workpiece and chuck mass, diameter, and length. Haas Lathe Operator's Manual, NGC, 96-8910 revision U, December 2024, sections 6.3, 6.6, and 6.10

The documented combination supports the following conditional operation candidates. These relationships are synthesis, not a qualified process list for an asset.

The flyer explicitly associates off-center milling, drilling, and tapping with Y-axis travel, live tooling, and a synchronized C axis. It describes a 12-station BMT65 turret and optional half-station indexing to 24 tool positions, only 12 of which accept driven tools. Twenty-four positions therefore do not mean 24 driven stations. Haas 39-20004B, PDF page 2

Tooling and usable envelope

Haas lists 4000-rpm live tooling, a 12-station BMT65 turret, and C axis as standard on the cited ST-20Y configuration. The flyer offers a 6000-rpm live-tool upgrade. A general manual's drive maximum does not establish that an individual machine has that upgrade. Haas ST-20Y, standard equipment; Haas 39-20004B, PDF page 2

The NGC manual identifies workpiece diameter, radial-tool extension, and required travel from centerline as Y-axis envelope factors. It describes live tooling as intended for medium-duty milling. Its separate VDI envelope discussion is turret-specific and does not define the BMT65 envelope. Haas December 2024 manual, sections 6.6.1 and 6.10.1–6.10.2

Check jaws, tool projections and supports for the actual motion. Check adjacent holders for interference before assigning stations.

Sub-spindle and automation options

Haas documents an optional A2-5 finishing sub-spindle for second-side work and synchronized part transfer. Its ST-20Y tooling section requires a BMT65 turret. The option is incompatible with VDI or BOT turrets and with the tailstock. It is compatible with the APL, but that loader can load and unload only the main spindle. Regional availability may vary. Haas A2-5 finishing sub-spindle, applicability and tooling sections, official legacy page

A tailstock supports a workpiece; the documented sub-spindle supplies a second chucking position. They are alternative configurations in this option family. The included sub-spindle ejector and an optional parts catcher perform different functions. Haas describes a bar feeder, sub-spindle, and parts catcher as a possible automation combination. Haas A2-5 finishing sub-spindle, overview and parts ejector sections

Synthesis distinguishes handling from cutting capability. Bar stock passage does not establish feeder compatibility, stock support, or stock straightness. A loader requires a suitable gripper and a reachable, repeatable loading position. A catcher requires a part that fits its handling conditions. Door control, guarding, control integration, and the installed automation package remain separate dependencies. The 2021 flyer describes APL part-shape templates and adjustable grippers, with different guarding provisions for CE compliance. Those statements apply to that documented package and period. Haas 39-20004B, PDF page 3

Second-side work depends on transfer grip, remaining stock, tool orientation and access. Establish those before committing to an unattended route.

Materials and performance limits

No material compatibility list is established by the model name. Exact alloy, condition, stock form, tooling, coolant, gripping, chip behavior, and feature geometry determine application suitability. The manual's mild-steel milling example concerns a stated tool and live-tool context; it is not evidence of unrestricted steel milling or a complete alloy list. Haas December 2024 manual, section 6.6.1

Use asset-specific evidence for process tolerances, rates, cycle times and delivery capacity. Haas ST-series catalog.

Source differences and review limits

Research checked on 29 October 2026 PDT. The product URL redirected to a reduced page during direct access. The official legacy page and indexed product text supplied the comparison and equipment descriptions. Neither supplies a verified generation changeover by serial number. Haas current product URL; Haas official legacy ST-20Y page

The product page gives Y travel as ±51 mm but its comparison table gives 100 mm total. The flyer gives 102 mm total. These source values remain distinct. A converted or rounded value here is not a guaranteed usable tool envelope. The auto-door section heading calls it standard, while the overview calls it optional and the details restrict regional availability. The sub-spindle drawbar-depth row pairs 1.50 in with 114.3 mm, which are not equivalent. Neither inconsistency establishes an installed option or a usable clearance. Haas ST-20Y, specification tables and option descriptions; Haas 39-20004B, PDF page 2

The dated references have separate applicability.

Related references

• Machine configuration references
• Machine references