ISO20/ISO25/ISO30 pull stud (retention knob), M8/M12 thread

1. Compact ISO20, ISO25 and ISO30 profiles

A pull stud works with the toolholder and spindle gripping mechanism. Selection requires the head, neck, flange, pilot, thread and functional lengths to be compared.

This description presents a nominal reference for the compact ISO20/ISO25/ISO30 family described for holders without drive slots. Size and the ISO name do not replace the drawing of the part required by the spindle.

2. Separate geometry, not an SK or ISO A/B alias

This family has its own symbols and nominal dimensions. It is not automatically an alias for SK30 or ISO 7388 A/B pull studs. Similar length or a shared thread does not prove interchangeability.

D1 is the flange dimension here, not the neck or pilot of another drawing. L1 is the overall length. Use the values and symbol meanings from this particular profile.

3. Nominal reference dimensions

Lengths and diameters are in millimetres. D5 contains a thread designation, not a numerical bore diameter. No thread pitch or class has been added. These are nominal references for drawing comparison, not measurements of a part.

ISO20 and ISO25 share M8 but have different lengths and head and neck diameters. Thread alone does not select between them. Compare ISO30 using its own values without borrowing SK30 dimensions.

4. Symbols and measurement points

L1 is the overall length from the head front to the end of the threaded portion. L2 is measured from the head face to the support plane and L3 from its rear boundary to that plane. They do not automatically describe thread length.

D1 retains the flange transverse dimension, D2 the head diameter, D3 the neck and D4 the pilot beside the thread. Do not equate D1 with wrench size or the D1 of another family.

5. Thread and gripping angle

D5 = M8 or M12 is a thread designation. It does not provide the complete pitch, hand or tolerance here. Compare those requirements with the part and holder drawing.

No numerical gripping-surface angle is stated for this reference. Do not copy an angle from a similar BT, SK or ISO A/B stud. Compare the correct head surface and gripping-mechanism geometry.

6. Identify passage and O-ring separately

The reference drawing does not establish an axial passage or sealing arrangement. It does not decide whether a specific part has a through bore, blind bore, recess or no bore. An opening in the head face alone does not establish its path.

The O-ring is a separate feature. Ring presence, number and position, and the machine-system contact location must be compared independently of external diameters and lengths. The table does not assign a passage or O-ring to ISO20/25/30.

7. Selecting the complete profile

Start with the complete drawing of the part required by the spindle. Compare:

1. The D2 head and D3 neck with the required gripping surfaces.
2. The D1 flange and D4 pilot while retaining the correct symbols.
3. The overall length L1 and L2/L3 distances from the specified faces.
4. The D5 thread and its complete requirements, together with the gripping angle.
5. The passage path and separate sealing requirements.

Do not select a part only by the number 20, 25 or 30 in its name. Nominal geometry does not establish composition, standard conformity, tightening torque or suitability for a specific machine model.

8. Short FAQ

Is ISO30 the same as SK30?
The name does not establish that. This compact family has its own profile; compare the complete drawing.

Is L1 a distance to the flange?
Not in this reference. L1 is the overall length.

What is D1?
The transverse flange dimension, not the neck diameter.

Is D5 the passage diameter?
No. D5 contains the M8 or M12 thread designation.

Does size identify an O-ring or through passage?
No. Check passage and sealing separately.