BT30/BT40/BT45/BT50 pull stud (retention knob) for JIS B 6339 tool holders, 45°/60°/90°, through and non-through variants, variants with O-ring

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€3.66

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BT30-45, for JIS B 6339 holders - non-through, M12, L43 mm, angle 45°

BT30-60, for JIS B 6339 holders - non-through, M12, L43 mm, angle 60°

BT30-90, for JIS B 6339 holders - non-through, M12, L43 mm, angle 90°

BT30C-45, for JIS B 6339 holders - through bore, M12, L43 mm, angle 45°

BT30C-60, for JIS B 6339 holders - through bore, M12, L43 mm, angle 60°

BT30C-90, for JIS B 6339 holders - through bore, M12, L43 mm, angle 90°

BT30CO-45, for JIS B 6339 holders - through bore, with O-ring, M12, L43 mm, angle 45°

BT30CO-60, for JIS B 6339 holders - through bore, with O-ring, M12, L43 mm, angle 60°

BT30CO-90, for JIS B 6339 holders - through bore, with O-ring, M12, L43 mm, angle 90°

BT40-45, for JIS B 6339 holders - non-through, M16, L60 mm, angle 45°

BT40-60, for JIS B 6339 holders - non-through, M16, L60 mm, angle 60°

BT40-90, for JIS B 6339 holders - non-through, M16, L60 mm, angle 90°

BT40C-45, for JIS B 6339 holders - through bore, M16, L60 mm, angle 45°

BT40C-60, for JIS B 6339 holders - through bore, M16, L60 mm, angle 60°

BT40C-90, for JIS B 6339 holders - through bore, M16, L60 mm, angle 90°

BT40CO-45, for JIS B 6339 holders - through bore, with O-ring, M16, L60 mm, angle 45°

BT40CO-60, for JIS B 6339 holders - through bore, with O-ring, M16, L60 mm, angle 60°

BT40CO-90, for JIS B 6339 holders - through bore, with O-ring, M16, L60 mm, angle 90°

BT50-45, for JIS B 6339 holders - non-through, M24, L85 mm, angle 45°

BT50-60, for JIS B 6339 holders - non-through, M24, L85 mm, angle 60°

BT50-90, for JIS B 6339 holders - non-through, M24, L85 mm, angle 90°

BT50C-45, for JIS B 6339 holders - through bore, M24, L85 mm, angle 45°

BT50C-60, for JIS B 6339 holders - through bore, M24, L85 mm, angle 60°

BT50C-90, for JIS B 6339 holders - through bore, M24, L85 mm, angle 90°

BT50CO-45, for JIS B 6339 holders - through bore, with O-ring, M24, L85 mm, angle 45°

BT50CO-60, for JIS B 6339 holders - through bore, with O-ring, M24, L85 mm, angle 60°

BT50CO-90, for JIS B 6339 holders - through bore, with O-ring, M24, L85 mm, angle 90°

BT45-45, for JIS B 6339 holders - M20, L70 mm, angle 45°

BT45-60, for JIS B 6339 holders - M20, L70 mm, angle 60°

BT45-90, for JIS B 6339 holders - M20, L70 mm, angle 90°

BT45C-45, for JIS B 6339 holders - M20, L70 mm, angle 45°

BT45C-60, for JIS B 6339 holders - M20, L70 mm, angle 60°

BT45C-90, for JIS B 6339 holders - M20, L70 mm, angle 90°

BT45CO-45, for JIS B 6339 holders - M20, L70 mm, angle 45°

BT45CO-60, for JIS B 6339 holders - M20, L70 mm, angle 60°

BT45CO-90, for JIS B 6339 holders - M20, L70 mm, angle 90°

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Product description

BT pull stud - selection by code and geometry

1. What a BT pull stud is

A pull stud is the part that interfaces with the tool-holder gripping mechanism in the spindle. The complete execution code distinguishes the size, head geometry, gripping angle, coolant passage and sealing arrangement.

Select the stud using the drawing required by the machine. A matching thread does not establish that the head, length or gripping surface is the same. This description applies to the catalog profile defined by the tables, not every possible BT stud.

Illustrative photo of an example BT pull stud with an O-ring. Check the dimensions of the selected code in the table.

2. Tool-holder system and spindle requirements

BT30, BT40 and BT50 identify sizes in the BT system. The holder designation is a starting point; the stud must also match the grip and geometry required by the spindle.

Mechanical selection covers all three areas.
Feature to compare	What to check
Thread	Thread designation and pitch required by the holder.
Grip	Head, neck, rear flank and distance from the support plane.
Passage and seal	Required bore and the presence and location of the O-ring.

3. Nominal family dimensions

The values below are nominal dimensions of one catalog profile. All linear dimensions are in mm; M is a thread designation. The head, neck, L1, L2, H, H1 and complete execution code must also match, not just the BT size and thread.

Illustrative BT profile with a 45° rear gripping flank. The table in the graphic gives nominal dimensions for BT40CO-45; it is not an inspection record for a specific stud.

Diameters and overall length
Size	Thread M	D [mm]	D1 [mm]	D2 [mm]	L [mm]
BT30	M12	12.5	7	11	43
BT40	M16	17	10	15	60
BT50	M24	25	17	23	85

Axial distances and flange
Size	L1 [mm]	L2 [mm]	H [mm]	H1 [mm]
BT30	23	18	4	3.5
BT40	35	28	5	4
BT50	45	35	8	8

4. Meaning of the dimension symbols

Symbol meanings apply to the geometry described by this table.
Symbol	Meaning and measurement location
D	Pilot beside the thread: Diameter of the cylindrical step beside the thread.
D1	Neck: Neck diameter below the head gripped by the mechanism.
D2	Head: Diameter of the gripping head.
M	Thread: External thread designation; compare its pitch with the holder requirement.
L	Overall length: From the head end face to the end of the thread.
L1	Distance to the support plane: From the head end face to the support plane at the flange on the threaded side.
L2	Distance from the rear head boundary: From the rear boundary of the head to the same support plane.
H	Pilot length: Length of the cylindrical pilot beside the thread.
H1	Flange thickness: Axial thickness of the flange.
θ	Rear gripping angle: Angle of the rear head flank at the D2-to-D1 transition.

Do not transfer a D, H or L1 value from a different drawing without checking its reference lines. The same letter may denote a different feature in another system.

5. C, CO and O-ring executions

Read passage and seal designations together with the complete code.
Designation	Meaning in this family	Selection check
C	Through hole	Compare the passage with the machine requirement.
CO	Through hole and O-ring	Also compare the seal and its seating location.
O	Execution with O-ring	The seal alone does not establish the bore arrangement.

An opening visible at an end face does not establish that the bore runs through the entire part. A blind bore, an identification socket and a through passage serve different functions. The absence of C does not establish bore depth or purpose.

6. Gripping angle and code interpretation

The angle is selected for the spindle grip, not just the thread.
Nominal θ	Surface	Selection
45°	Rear flank of the gripping head	Compare θ and its reference on the required drawing.
60°	Rear flank of the gripping head	Compare θ and its reference on the required drawing.
90°	Rear flank of the gripping head	Compare θ and its reference on the required drawing.

Example BT40CO-45: BT40 identifies the size, C a through hole, O an O-ring, and 45 the nominal rear θ angle. The front of the head has a separate 60° angle; do not confuse it with the rear flank gripped by the mechanism.

7. Selection and inspection before installation

Complete code: Size, execution and angle required by the spindle.
Geometry: Thread and pitch, L, gripping distances, head and neck.
Passage: Required bore arrangement; a dark opening at the end face does not identify the part.
Seal: O-ring presence and position, seal condition and seating surface.
Installation: Requirements and tightening torque from the machine and holder instructions.

8. Short FAQ

Does an M16 thread alone confirm compatibility?
No. Also compare the head, neck, gripping lengths, rear angle, passage and sealing execution.

What is the difference between C and CO?
C identifies a through hole; CO identifies a through hole and O-ring. Select using the complete execution code.

Does an O-ring establish that the bore is a through hole?
No. Sealing and bore arrangement are separate features.

Which surface does θ refer to?
The rear gripping flank of the head at the D2-to-D1 transition, not the separate front head angle.

What is the sales unit for BT40CO-45?
BT40CO-45 is sold as one pull stud per sales unit. Check the unit for the other variants at the selected code.