Dimension Table for Base Holes: Studs, Nuts, and Screws

1. What Are Studs, Nuts, and Screws?

A stud refers to a type of fastener that has no head and is threaded at both ends, such as a double-end stud or a welding stud.

A nut, or a cap nut, is a part that is screwed together with a bolt or screw to serve a fastening function. It is an essential component in all manufacturing machinery. Depending on the material, it can be classified into several types like carbon steel, stainless steel, and non-ferrous metals (such as copper).

A screw, colloquially known as a bolt or screw bolt, usually does not require a nut and directly cooperates with two objects. The tool typically used is a screwdriver; the head often features a straight slot, cross slot, hexagon (internal and external), or plum blossom slot.

2. What Does the Term “Thread Bottom Hole Size” Refer To?

The size of the thread bottom hole refers to the diameter of the internal thread.

Generally, the bottom hole refers to the diameter of the pre-manufactured hole before the tap is used to thread the internal thread. This typically refers to the inner circular hole of the machined part, specifically the circular hole at the very bottom or surface.

During the threading process with a tap, the cutting edge primarily cuts the metal but also exerts pressure on it. This causes the metal to protrude and flow towards the tooth tip. Therefore, before threading, the drilled hole diameter (i.e., the bottom hole) should be larger than the inner diameter of the thread.

The diameter of the bottom hole can be found in the manual or calculated using the following empirical formulas:

• For brittle materials (such as cast iron, bronze, etc.): Drill hole diameter d0 = d (thread outer diameter) – 1.1p (pitch)
• For ductile materials (such as steel, copper, etc.): Drill hole diameter d0 = d (thread outer diameter) – p (pitch)

3. Dimension Table for Stud Base Holes

4. Dimension Table for Nut Base Holes

5. Dimension Table for Screw Base Holes