| Article number | M1257 |
|---|---|
| Turret interface | BMT40 — BMT (Base Mount Turret, flange mount) |
| Configuration | BMT PSC (Capto-compatible) axial driven tool holder |
| Orientation | Axial |
| Output coupling | PSC40 polygon taper (ISO 26623) — C4 size |
| Coolant | EC & TC — external and through coolant |
| Drive ratio | 1:1 |
| Max spindle speed | 6,000 rpm |
| Max output torque | 32 Nm |
| Coupling clamping torque | 45 Nm |
| Brand | Mongtec Precision Inc. — Taiwanese brand, designed and engineered in Taichung, Taiwan |
| H1 | 72 |
|---|
Dimensions in mm from Mongtec Tool Holders — VDI & BMT, Ver 2026.3, page 65. Tolerances and mounting details confirmed at quotation.
Source: Mongtec VDI & BMT Driven Tools catalogue, Ver 2026.3 — BMT-40 PSC (Capto-compatible) driven tool holders.
The driven spindle points along the Z axis, parallel to the lathe spindle. This is the configuration for face drilling, face tapping and end milling on the part face.
The output is not a collet nut. M1257 ends in a PSC40 polygon taper coupling, so cutting tools are changed as complete PSC40 assemblies — the same coupling family the machine may already use on its static stations.
Gear ratio 1:1 — tool spindle speed equals turret drive speed. The direct relationship makes speeds and feeds straightforward to calculate from the machine's live-tool rating.
PSC40 is a polygon shank cone to ISO 26623 — an open international standard. The C4 designation refers to the same nominal size under the Coromant Capto name. A PSC40 output lets one driven station carry drills, mills, boring bars and tapping heads as pre-set assemblies, with repeatable location on every change, instead of a collet swap at the machine.
See Mongtec PSC40 tooling for the article numbers that mount on this output, or the PSC / Capto size overview for how PSC40 sits against the other sizes.
Coromant Capto® is a registered trademark of AB Sandvik Coromant. Mongtec is an independent brand with no affiliation to, endorsement by or licence from Sandvik. The Capto designation is used here only to identify the ISO 26623 polygon taper size; interchange in any specific application is confirmed by Mongtec engineering at RFQ.
Whether a given machine carries a BMT40 turret, and whether that turret takes this bolt pattern, is confirmed per machine at RFQ — send the machine model and a photograph of the turret face.
| Article no. | Turret | Orientation | Output | Torque |
|---|---|---|---|---|
| M0407 | BMT45 | Axial | PSC32 | 25 Nm |
| M8307 | BMT45 | Radial | PSC32 | 25 Nm |
| M7517 | BMT55 | Axial | PSC32 | 25 Nm |
| M0817 | BMT55 | Radial | PSC32 | 25 Nm |
| M9327 | BMT65 | Axial | PSC40 | 32 Nm |
| M2427 | BMT65 | Radial | PSC40 | 32 Nm |
| M4176 | BMT60 | Axial | PSC40 | 32 Nm |
M1257 is built for the BMT40 turret interface. Because BMT is an industry de-facto standard rather than an ISO or DIN published standard, bolt circle, key position and drive coupling can differ between machine builders even at the same nominal size. Send Mongtec your machine model and a photo of the turret face and engineering confirms the fit before anything is quoted.
M1257 is rated to 6,000 rpm with 32 Nm of output torque at a 1:1 drive ratio. The usable figure is whichever is lower: this rating or your machine's live-tool drive rating.
They are the same nominal polygon taper size under ISO 26623. PSC40 is the standard designation; C4 is the Coromant Capto name for that size, and PSK C4 is the German-language form. Mongtec supplies PSC40; interchange with another maker's tooling in a specific application is confirmed by Mongtec engineering at RFQ.
M1257 is supplied with EC & TC — external and through coolant. Coolant routing on the turret side differs between machine builders, so confirm the machine's coolant arrangement in the enquiry.
Send the machine model, the turret station you want to use and the tools you intend to run. Anything you do not know, Mongtec works out from the machine model — an incomplete enquiry is still worth sending. Dimensioned drawings for M1257 are supplied by email once the enquiry is open.
Mongtec PSC40 tooling · How to choose a driven tool holder · All turret interfaces