What is a shoulder bolt and what is it used for?

What is a Shoulder Bolt (Shoulder Screw, Stripper Bolt)?

A shoulder bolt, also known as a shoulder screw or stripper bolt, is a bolt have shoulder or screw with shoulder of fastener that includes three parts: a head, an unthreaded shoulder under the head, and a threaded tip.

The following is a detailed description of the three parts of the shoulder bolts and how they function:

1. Head: The top of a shouldered bolt, screw head drive usually a hex head shoulder bolt or socket head shoulder screw（also can be slotted, Phillips,Robertson）, which can be tightened and loosened with a screwdriver, Allen wrench or socket. The diameter of the bolt with shoulder head is usually larger than the shoulder and provides a good surface area to carry the load.

1. Shoulder: The shoulder is the unthreaded part of the bolt, located between the head and the threaded part. The diameter of the shoulder is larger than the threaded part, and it serves as the axis of rotation for any parts that need to be pivoted or moved, allowing them to slide or rotate around the bolt. It is this part that gives the shoulder bolts its name and distinguishes it from other screws or bolts.
2. Thread Section: This section is used to fix the bolt in place or into threaded holes with nuts. The diameter of the threaded section is usually smaller than the shoulder.

What are shoulder bolts used for?

shoulder bolts are universal fasteners used in different industries to connect parts to rotate and slide while maintaining alignment. The following are the main functions and advantages of shoulder bolts:

1. Pivoting: Allowing parts to rotate or pivot around the shoulder.
2. Alignment: Provides precise alignment and positioning of components.
3. Mounting: Used as a mounting for shafts or moving parts in pulley systems.
4. Guide Pins: Enabling sliding or guided movements in mechanical applications.
5. Load Bearing: Supports lateral loads that ordinary screws cannot handle.

Here are some common applications for shoulder screws:

• Automotive
• Aerospace
• Electronic and Appliances
• Jigs and Fixtures
• Robotics
• Furniture

What are the commonly used shoulder bolt materials?

Shoulder bolts are typically made from a variety of materials, with the most common materials including:

• 304 Stainless Steel
• 316 Stainless Steel
• 201 Stainless Steel
• Alloy Steel
• Brass
• Plastics

How to measure a shoulder bolt dimensions？

This is one of the most frequently asked questions about shoulder bolts, and if you want to accurately measure a shoulder bolt, you need to determine a few key dimensions. Here’s a clear and concise step-by-step guide:

1. Measure the Shoulder Diameter:
   • Use a caliper to measure the outer diameter of the unthreaded shoulder, This is the largest diameter part of the bolt.
2. Determine the Thread Diameter:
   • Measure the diameter of the threaded part at the end of the bolt. Ensure the caliper fits snugly around the threads for an accurate measurement.
3. Find the Shoulder Length:
   • Place the end of the caliper at the base of the bolt head and extend it to the start of the thread. This measures the length of the shoulder, not including the head or threads.
4. Check the Thread Length:
   • Measure the length of the threaded section from where the threads begin to the tip of the bolt.
5. Measure the Head Diameter:
   • Measure across the widest part of the bolt’s head. This is often the tool engagement area.
6. Document the Thread Pitch or Type:
   • If thread specification is needed, identify the pitch (for metric shoulder bolts) or count the number of threads per inch (for inch shoulder bolts).

Taking precise measurements using a tool like calipers will give you the complete outline of the

US shoulder bolt dimensions

Shoulder Diameter	Thread Size	Thread Length	Head Diameter	Head Height	Allen Wrench Size
1/4″	#10-24	3/8″	3/8″	3/16″	1/8″
5/16″	1/4″-20	7/16″	7/16″	7/32″	5/32″
3/8″	5/16″-18	1/2″	9/16″	1/4″	3/16″
1/2″	3/8″-16	5/8″	3/4″	5/16″	1/4″
5/8″	1/2″-13	3/4″	7/8″	3/8″	5/16″
3/4″	5/8″-11	7/8″	1″	1/2″	3/8″
1″	3/4″-10	1″	1-5/16″	5/8″	1/2″

Metric shoulder bolt dimensions

Shoulder Diameter	Thread	Thread Length	Head Diameter	Head Height
M6	5mm x 0.8	9.75mm	10mm	4.5mm
M8	6mm x 1.0	11.25mm	13mm	5.5mm
M10	8mm x 1.25	13.25mm	16mm	7mm
M12	10mm x 1.5	16.4mm	18mm	9mm
M16	12mm x 1.75	18.4mm	24mm	11mm

If you need more detailed specifications (including material and mechanical properties), or need to customize shoulder bolts size and specifications according to specific requirements or technical drawings. Please feel free to contact Shanghai Hengrui Industrial Co., Ltd.