Static & Driven Tool Holders for HAAS Machines

BMT (Block Mounted Tooling) is a turret interface where each tool block bolts to the face of the turret disc on a defined bolt pattern, with a central pilot and a drive key that locates and transmits the rotation to driven holders.

BMT 65 is the 65 mm bolt-pattern size, the larger of the two common BMT sizes, suited to mid-frame lathes in the 200–500 chuck range. It is a bolted-block interface rather than a cylindrical shank.

The VDI turret (DIN 69880 / DIN 5482) used on older machines is a cylindrical shank interface (the holder has a VDI shank that drops into a bore on the turret and clamps radially).

BMT differs mechanically and is not interchangeable with VDI: a BMT 65 holder will not mount on a VDI turret and vice versa and the holder selection is dictated by which interface your machine carries.

The HAAS ST/DS and modern Doosan range here is BMT 65; the older CTX, Graziano and L/SKT disc-turret machines are VDI 40.

A static holder carries a stationary cutting tool (a turning tool, a boring bar, a parting blade) that does the cutting while the spindle drives the work. These are the holders for the conventional turning, facing, boring and parting operations the lathe was built for. A driven (live) holder carries a rotating tool (an end mill, a drill, a tap) that is powered by the turret drive, allowing milling, drilling, reaming and tapping to be performed on the lathe while the workpiece is held still in the spindle.

The driven holder is what turns the lathe into a turn-mill because it brings the secondary machining operations onto the turret, so a part can be turned, then drilled and milled without leaving the machine.

The Y-axis machines in the range (ST 20Y through ST 35Y, DS 30Y, the PUMA MX and TT, the LM TTSY and the L2100Y/L2600Y )carry the off-centre Y-axis that lets a driven tool reach across the spindle centre line, which is how slots, flats and bolt-hole patterns are machined on the lathe.

The ST number is the number of tool stations on the turret (12ST is a 12-station turret, 16ST a 16-station). The bulk of the machines we carry are Star-Type 12ST BMT 65, the Haas ST/DS, the Doosan PUMA, HI TECH, SKT, LM, L series and CUTEX. The 52 TT and TTT SY are the Star-Type 16ST BMT 65 machines, with the larger turret stations count for the more toolled twin-turret configurations.

The turret designation is printed on the turret and stated in the machine manual, and on the machine itself the number of tool positions is visible (count the clamping blocks around the turret face).

Within a machine family the turret can vary by spec, so identify the turret and not just the model: picking the wrong station count is the most common ordering mistake, because a 12ST holder does not fit a 16ST turret and vice versa, even on identical BMT 65 machines.

The suffixes describe the lathe’s capability.

• Y denotes a Y-axis on the turret that lets a driven tool move across the spindle centre line which is essential for milling flats, slots and bolt-hole patterns

• SY denotes a sub-spindle in addition to the Y-axis (a second spindle for back-working), so the part can be finished on the back face after parting

• M denotes a turn-mill (driven-tool-capable) machine

• MS a turn-mill with sub-spindle

• TT denotes a twin-turret machine where two turrets work the spindle and a sub-spindle simultaneously.

For tool selection the suffixes do not usually change the holder shank (the BMT 65 interface is common) but they change which tools make sense.

A Y or SY machine earns its driven milling and drilling heads; an M or MS machine takes the driven axial tools for off-spindle drilling and tapping; a TT machine takes a twin set of holders because both turrets carry tooling.

The LM 2500 TTSY, SKT 250 LMS-style and PUMA MX 2000/2500/2600 are the higher-spec variants and tend to be tooled more heavily than an equivalent plain-turning lathe.

The HAAS models here are the ST and DS turning centre families: ST 20Y, ST 25Y, ST 30Y, ST 35Y and the DS 30Y (dual-spindle, Y-axis). All are Star-Type 12-station BMT 65 machines and take the same BMT 65 holder range.

The Y suffix on every HAAS model here means they are all Y-axis machines and that driven milling and drilling is part of their spec, so the tool list for a Haas in this category includes both static turning blocks and driven live tools.

A typical HAAS ST tooling set starts with the static turning and parting blocks (OD turning, facing, boring and part-off), then adds the driven side (an axial drilling/milling head for centre-line work and a radial head for cross-drilling and slot milling) matched to the ER collet size the driven head carries.

The DS 30Y carries a sub-spindle, so the same holder type is provided in a second set for the opposing stations and the Y-axis reaches the off-centre milled features.

The Doosan PUMA family is the principal group: the PUMA 2100, 2600, 300 M/MS, 3100, MX 2000/2500/2600, TT 2000/2500, V400M, VT 350 TM, VT 450M and the PUMA Inverturn 3000 are all Star-Type 12ST BMT 65.

Alongside sit the Doosan HI TECH 200–450, the SKT and LM twin-turret series (SKT 200/210/250, LM 2000/2500 with the TTM/TTMS/TTSY variants), the L2100Y/L2600Y and the L300 LMA/LMC/MSA/MSC family, plus the CUTEX 240 and the 52 TT / TTT SY 16ST machines.

These share the same BMT 65 holder interface as the HAAS models in the category (the holder is determined by the interface and the turret, not the brand).

So a BMT 65 static block or driven head listed for a PUMA 2600 will fit any other 12ST BMT 65 machine in the range.

The static side of the turret carries the conventional lathe tooling;

• A square-shank turning block holds the indexable turning and facing insert tool holders

• A boring-bar holder takes a cylindrical boring bar for internal turning

• A parting block holds a parting blade for parting-off and grooving.

Each is a static block that bolts to the BMT 65 turret face, sets the tool on the machine’s centre height, and indexes repeatably as the turret stations.

The block sets the tool tip to the correct centre height for the spindle; the machine’s centre height is a fixed figure, and the holder adjusts the tip to it via shims or adjustment screws on the holder.

A starter static kit is a pair of turning blocks (one roughing, one finishing), a boring-bar holder and a parting block, that quartet covers the bulk of the turning work and lets each tool stay in its own station for the life of the job.

Driven (live) tools are classified by the direction of the tool axis relative to the spindle.

An axial holder drives the tool parallel to the spindle centre line and is the choice for drilling, reaming and tapping along the part axis, and for end-milling along the centre line.

A radial holder drives the tool perpendicular to the spindle and is the choice for milling flats and slots on the side of a part, cross-drilling, and machining features across the spindle axis.

A holder that offsets the tool from centre lets the Y-axis reach the off-centre positions, which is what the Y on a HAAS ST or PUMA MX is for.

A turn-mill tooling set generally has an axial drilling/milling head for centre-line work and a radial milling head for the cross-work (that pair unlocks the milling capability the machine carries).

Thread-milling, tapping and angle heads that change the tool axis are added as the work demands. The holder takes the BMT 65 block to the turret and carries an ER collet, a shrink-fit seat or a Weldon holder for the rotating tool itself.

The driven holders on BMT 65 lathes overwhelmingly use ER collets (ER16 on the smallest, ER20 and ER25 on the mid-range, ER32 on the larger) which clamp a cylindrical tool shank by a nut compressing the slitted collet.

ER collets cover a span of shank diameters around their nominal size, so a set of collets handles a spread of end-mill and drill shanks and the runout is low enough for general milling and drilling.

For precision and high-speed milling a shrink-fit holder takes a solid-carbide tool with an exact shank diameter, heated and cooled to lock the tool with the lowest runout and best balance; Weldon side-lock holders suit larger end mills with a flat because a set-screw bears on the flat to stop axial slip under heavy milling. Match the collet type to the tool and the duty:

ER for general use, shrink-fit for speed and precision, Weldon for heavy milling.

Most BMT 65 static and driven holders we carry are available in a through-tool coolant variant.

The coolant is delivered through the holder and the tool, rather than only externally. For a driven drilling or milling tool, through-coolant flushes the chips from the hole and cools the cutting edge directly, which is essential for deep drilling and high-speed milling and extends tool life considerably.

For a static boring bar, through-coolant reaches the cutting edge in the bore where external coolant struggles.

Through-coolant needs the holder to carry the internal ducting and the correct interface to the machine’s coolant supply at the turret and the tool itself must be a coolant-through tool.

If your machine has through-coolant at the turret (and all the modern Haas and Doosan models we carry do) pick the through-coolant holder variant where the operation benefits, particularly deep drilling and milling.

The gain in chip control and tool life is worth the small additional cost.

The twin-turret machines (the 52 TT and TTT SY (16ST), the PUMA TT 2000/2500, the LM/SKT TTM/TTSY variants and the LV500 LM/RM) carry two turrets that work the main spindle and the sub-spindle simultaneously.

Each turret is its own BMT 65 interface and needs its own set of holders, so a twin-turret machine is tooled roughly twice over with one set per turret, sized and chosen for the operations each turret performs.

In practice one turret carries the main-spindle OD and ID work while the other carries either the sub-spindle back-work or the driven milling; the exact split is set by the process.

The holders are the same BMT 65 parts as on a single-turret machine but the kit is doubled and the tool list balanced across the two turrets. If you are speccing a TT machine, plan the tooling across both turrets together because a holder on the wrong turret or an unbalanced list wastes the capacity the twin-turret machine was bought for.

Centre height (the distance from the spindle centre line to the cutting tip) must be exact for accurate turning and a clean finish and the BMT static block is designed to set it. The block bolts to the BMT 65 turret face and mounts the turning-tool holder at the machine’s centre height, with the fine adjustment for tip height on the holder or by shims beneath the insert tool holder. Set the tip to centre using a height gauge or by touching the tool to a bar held between centres, then lock the tool.

On a BMT turret the block orientation is fixed by the bolt pattern and the drive key, so a holder that is the correct part for the machine sets the tool close to centre by design; the final set is by tip adjustment.

A tool off centre (even slightly high or low) turns a tapered or poor-finish diameter, so taking the time to set centre once per tool pays back on every part that follows.

The quick check is a light cut and a measurement; a true diameter means the centre is right.

Keep the turret interface clean and correctly torqued.

The accuracy of a BMT system depends on the block seating cleanly on the turret face, swarf and coolant residue between the mating faces is the most common cause of a block not indexing true, which shows up as a poor or inconsistent part.

Wipe the turret face and the block mating faces before fitting and torque the clamping bolts to the machine maker’s figure (under-torqued blocks shift under cut, over-torqued ones distort the interface).

On driven holders the collet and nut are the moving parts. Keep the collet clean and free of swarf, inspect the nut and the drive key for wear and replace a collet that has begun to mark the tool shanks or let in runout.

The turret drive coupling itself is inspected at the service intervals the machine manual specifies because a worn coupling causes driven-tool runout and poor milling finish.

Store spare blocks clean and racked, with the tooling left in place so a block returns to use ready-set.

Begin with the static turning set; a square-shank turning block for your main OD turning and facing, a second for a finishing tool, a boring-bar holder for the internal work and a parting block for parting-off.

That quartet is the baseline that lets the lathe do what it was bought for, with each tool in its own permanent station. Add a second turning block so roughing and finishing tools are not swapped between operations.

For a turn-mill, add an axial driven drilling/milling head with an ER-collet set to cover centre-line drilling and end-milling and a radial milling head for the cross-work; that pair unlocks the milling capability the machine carries. Thread-milling, tapping and angle heads come as the work demands.

On a twin-spindle or twin-turret machine, mirror the set for the second spindle or second turret. Tell us your model and the parts you intend to make and our engineers will put together a matched tooling list that fits the BMT 65 turret and covers the work from the first set-up.