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BT40 MAS 403 short ER collet chuck ER25 / ER32, L = 36 mm

Kortools

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€51.28

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BT40-ER25-36L

BT40-ER32-36L

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Product description

BT40 MAS 403 short ER collet chuck: ER25 and ER32, L = 36 mm

Very short ER collet chuck with a BT40 (MAS 403 BT / JIS B 6339) taper. The ER collet and the nut sit inside the holder flange, so the front protrudes only 9 mm beyond the flange (L = 36 mm). The tool stays close to the spindle: short projection and high rigidity.

Available collet sizes: ER25 (shanks 2–16 mm) and ER32 (shanks 2–20 mm). Select the variant when purchasing.

Applications

clamping drills, end mills and reamers with cylindrical shanks in ER25 or ER32 collets (DIN 6499)
work with the shortest tool projection: short tools, little space between spindle and workpiece
precise machining: holder runout ≤ 0.003 mm
CNC milling machines and machining centres with a BT40 spindle (MAS 403 BT)

Specification

Taper type	BT40 (MAS 403 BT / JIS B 6339)
Tool clamping	ER collets to DIN 6499: ER25 or ER32
Clamping range	ER25: 2–16 mm; ER32: 2–20 mm
Nut	inside the holder flange; spanner size SW in the dimension table
Length L	36 mm (front 9 mm beyond the flange)
Holder runout	≤ 0.003 mm
Balance grade	at least G6.3 (many pieces are balanced to G2.5 at 25,000 rpm: ask us and we will check the label of the specific piece)
Coolant	AD version (central coolant supply)
Material	alloyed case-hardened steel (carburized depth 0.8 ± 0.2 mm)
Hardness	HRC 56–60
Taper	taper tolerance < AT3, surface roughness Ra < 0.2 µm
Standard	MAS 403 BT / JIS B 6339 (taper), DIN 6499 (ER collets)
Included	ER collets are not included and are selected separately

Balance grade: at least G6.3. Many holders of this type are balanced to G2.5 at 25,000 rpm (more precise). If you need G2.5 for high spindle speeds, write to us before purchasing — we will check the label of the specific piece before shipping.

Coolant: AD version (coolant through the spindle centre). If your spindle supplies coolant through the flange (form B), write to us before purchasing.

Dimension table

Dimension drawing – BT40 MAS 403 short ER collet chuck ER25 / ER32, L = 36 mm

Variant	Collets	Clamping range [mm]	SW [mm]	L [mm]	L1 [mm]
BT40-ER25-36L	ER25	2–16	27	36	9
BT40-ER32-36L	ER32	2–20	34	36	9

SW – spanner size for the nut, L – length from the flange face (spindle side) to the holder front face, L1 – projection of the holder front beyond the front face of the flange, clamping range – shank diameters covered by ER collets of the given size.

Read the complete designation of the selected variant. For example, BT40-ER25-36L means a BT40 taper, ER25 collets and length L = 36 mm.

How to select

Check that the spindle has a BT40 interface (MAS 403 BT), not SK40.
Select the ER size by the shank diameter: ER25 – 2–16 mm; ER32 – 2–20 mm. The collet is selected for the specific shank diameter.
This is the shortest ER holder. If you need a longer projection, choose a standard ER collet chuck (lengths 60–200 mm).

FAQ

Will it fit my machine?
The holder has a BT40 taper to MAS 403 BT (JIS B 6339). Before purchasing, confirm that the standard, size and pull stud match the machine spindle requirements. BT40 and SK40 are different tapers, so the designation “40” alone is not sufficient to confirm the selection.

How does it differ from a standard ER collet chuck?
The collet and the nut sit inside the flange, so the holder ends 9 mm beyond the flange, while a standard ER collet chuck is 60–200 mm long. This gives the shortest tool projection and the highest rigidity.

Are ER collets included?
No. The ER25 or ER32 collet is selected separately for the tool shank diameter.