Mazak BT40/BT50 pull stud (retention knob) for JIS B 6339 tool holders, M16/M24 thread, C/CO, through bore

Availability:

Select a variant to see available quantity pcs.

€7.99

Shipping costs are not included in the price.

Quantity

pcs.

Shipping time: 24 hours

Ask about the product

Select a product variant:

Individual variants may differ in price

Variant

Select

Mazak BT40 C, for JIS B 6339 holders - through bore, M16, L44.1 mm, angle 45°

Mazak BT50 C, for JIS B 6339 holders - through bore, M24, L65.2 mm, angle 45°

Mazak BT40 CO, for JIS B 6339 holders - through bore, M16, L44.1 mm, angle 45°

Mazak BT50 CO, for JIS B 6339 holders - through bore, M24, L65.2 mm, angle 45°

Click Available to show variants with 24h shipping

Product description

Pull stud for Mazak BT40 BT50 – profile selection

1. Pull stud and geometry required by the spindle

A pull stud screws into a toolholder and its head engages the spindle gripping mechanism. Selection includes the complete head and neck profile, thread, lengths, gripping surfaces, passage and sealing arrangement.

The nominal reference geometries below are Mazak BT40 and BT50 profiles, not measurements of a specific part. Compare the required profile with the machine model and spindle-type documentation; the machine brand alone does not specify one universal stud.

2. Separate Mazak BT family

Mazak BT geometry has its own length, head and neck. It is not automatically a general BT/MAS403 profile or a pull-stud profile for Haas. A shared BT size or thread does not make these geometries interchangeable.

The required part drawing also defines head position relative to the flange and the correct gripping surface. Similar individual dimensions do not establish the complete profile.

3. Nominal reference dimensions

The table retains the complete stated nominal dimensions of this reference geometry. Lengths and diameters are in millimetres. M retains the metric thread designation without adding a pitch or thread class.

Reference profile	M	L [mm]	L1 [mm]	D2 [mm]	D1 [mm]	D3 [mm]	D [mm]	d [mm]
Mazak BT40	M16	44.1	19.1	18.8	12.45	22	17	7
Mazak BT50	M24	65.2	25.2	29	20.83	37	25	10

External dimensions do not assign a bore path or O-ring to a real part. Retain the symbols and measurement points of the correct drawing when comparing profiles.

4. Symbols and correct measurement points

Symbol	Meaning only in this geometry
L	Overall length
L1	Head face → support plane
D2	Head diameter
D1	Neck diameter
D3	Flange transverse dimension
D	Pilot diameter beside thread
d	Axial-feature diameter in drawing

L is the overall length from the head front to the end of the threaded portion. L1 runs from the head front to the flange support face; it is not the thread length.

In this BT reference D is the pilot, D1 the neck, D2 the head and D3 the transverse flange dimension. Lowercase d is an axial feature in the drawing. Do not read it as the neck diameter.

The transverse flange dimension does not automatically specify a wrench size. Retain the endpoints of each dimension line.

5. Rear 45° slope and 30° head front

The reference drawing separates two angle callouts. The 45° angle belongs to the rear gripping slope between the maximum head diameter and neck. A separate 30° callout is marked at the head front.

Position in the drawing	Reference angle
Rear gripping slope of the head	45°
Head front	30°

Do not substitute one surface for the other when comparing angles. A nominal drawing callout does not replace identification of the profile or measurement of a specific part.

6. Bore and sealing as separate features

Reference d is 7 mm for BT40 and 10 mm for BT50. It is the nominal diameter of the axial feature shown in the drawing; it does not prove a through passage in an actual stud.

A through passage connects both ends of the part. A blind bore ends inside it. A visible opening in the head face does not establish the bore path.

The O-ring and passage are separate features. Compare ring presence and number, groove or seal position and contact face with the machine-system requirements. C/CO codes do not replace this check and should not inherit their meaning from another family.

7. Selection for the model and spindle type

Start with the complete drawing of the stud required by the machine model and spindle type. Compare in this order:

The correct Mazak BT or Mazak CAT family.
The thread, thread pitch and required type.
The head, neck, pilot and flange using their own symbols.
The overall length and head-to-support-face distances.
The rear gripping surface and separate head front.
The passage and separate sealing requirements.

M16 or M24 does not specify a pitch here. Do not infer pitch from size alone or resemblance to another part. The reference does not establish compatibility with every spindle sharing that name.

8. Short FAQ

Does Mazak BT use the same stud as general BT?
Do not assume so. This reference has its own lengths and head profile; compare the complete drawing.

Does D1 identify the same feature in Mazak BT and CAT?
No. It is the neck in BT and the pilot near the thread in this CAT geometry.

Do 45° and 30° describe the same slope?
No. The 45° callout is at the rear gripping surface and 30° at the head front.

Does CO alone prove an O-ring or through passage?
Do not infer the actual passage or sealing arrangement from the code alone. Check them separately.