Buyer’s Guide to Precision Shoulder Screws Refreshed for 2023!

Welcome to our Precision Shoulder Screws Buyer’s Guide Refreshed for 2023! Here are a couple of important details that you must know before setting off to buy Precision Shoulder Screws.

5 Things to Know When Buying Precision Shoulder Screws

Just as Dowel Pins and Retaining Rings are used to locate or hold parts together within a precision assembly or a fixture, so are Precision Shoulder Screws.

Yet shoulder screws are far more versatile. When installed, the unthreaded shoulder acts as a shaft for rotating items such as bearings and bushings, precision spacing, machinery support, and motion guiding. The exacting tolerance of Precision Shoulder Screws makes them ideal for use with other precision components.

They are broadly used across various applications in many industries, including: aerospace, electrical motors, hydraulic equipment, instrumentation, tooling and fixtures, machinery, military and many more.

1. What is a Precision Shoulder Screw? 

Precision Shoulder Screws are generally classified as part of the electronic hardware family. They resemble socket cap screws with an enlarged, unthreaded cylindrical shoulder under the head, and are used to hold parts together within a precision assembly.  Sometimes referred to as “tight tolerance” shoulder screws, they are not governed by any official IFI, ANSI or ASME standard..

Precision shoulder screws are composed of three main parts: the head, the shoulder and the thread.

2. What materials and sizes are available?

Precision Shoulder Screws are readily available off the shelf in type 18-8/303 stainless steel and 416 stainless steel.

Standard stock sizes for the shoulder diameter are Inch from 1/8 to 1/2 and Metric from M4 to M12. The thread class is 2A and the tolerance on the shoulder diameter varies from +.000/-.001 to -.0005 to -.0015 depending upon the manufacturer. Now that’s precise!

316 stainless steel, alloy and other exotic materials, and special diameters and lengths are available in certain sizes and/or for special order and usually involve a lead time.

3. What information do I need for ordering?

The easiest way to order is by manufacturer part number. If you don’t have one, you’ll need to specify shoulder diameter, shoulder length, thread size, material and drive type; for example: 3/16” shoulder diameter x 1” long x 8-32 thread in SS18-8 with a hex-socket drive.

Precision shoulder screws are available in hex socket and slotted drives. Philips, torx and star drives may be available in certain sizes as well.

Typical head styles are a modified fillister with a flat top where the head diameter is about twice the head height and does not need to be specified. Low head fillisters are available in certain sizes.

4. Are there other factors to consider?

YES! One surefire way to save money and shorten delivery time is to cross the OEM brand part on your bill of materials to a functional equivalent.

Popular brands include: Amatom, Cambion, Concord, Globe, HH Smith, Keystone, Lyn-tron, Misumi, Pic Design, RAF, and WM Berg. A comprehensive selection of Precision Shoulder Screws is also offered by McMaster-Carr (tight tolerance series), MSC, and Grainger.

Let’s take the above example of a 3/16” shoulder diameter x 1” long x 8-32 thread in SS18-8 (300 Series) with a hex-socket drive. This part is offered by the seven brands (yes, seven!) listed below under the following part numbers:

  • Grainger 6JY20
  • Lyn-tron SS7431-00
  • McMaster-Carr 94035A208
  • MSC Industrial 67313726
  • Pic Design 4423
  • RAF 6931-SS
  • WM Berg PZ-14-3

You can also find Precision Shoulder Screws under their Mil-Spec numbers, which include MS51575 and MS51576 and are DFARS compliant with full paperwork. The above part is equivalent to a Mil-Spec MS51576-14.

5. What level of certification is required?

Generally, a Certificate of Conformance or a COC is sufficient for your customer. Full certification with material certs and test reports are often available for USA-made and Mil-Spec parts for a fee.

Precision Shoulder Screws at MF Supply

We currently offer:

  • The full range of commercial and mil-spec parts, including parts that are DFARS and ROHS compliant.
  • MS51576 Now available for online purchase!
  • Brand names and generic equivalents.
  • Custom made parts per print in non-standard and exotic materials and finishes.
  • Metric, Inch, and Mil-Spec options & functional equivalents

For more detailed information on Precision Shoulder Screws, visit us at our website or Request a Quote today, and our MF Supply team of sourcing experts can help you find what you need. “Finding the right screw for you” is our tag line after all!

Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.

MF Supply Work With Us

Six Reasons To Buy From MF Supply

  • Full eCommerce Enabled Website With Technical Manual Available 24/7 – Visit our website and Create a New Account, track online orders, browse our product catalog, check technical specs, subscribe to our blog, or buy online.  We are adding items and improving functionality daily!
  • Same Day Shipping From The USA – Our hardware products are in stock and ship to you directly from our USA based distribution centers. 
  • Functional Equivalents To Expensive Brand Names- We stock and source alternatives to brand name fasteners, reducing long lead times and saving you money.
  • Creatively Solve Problems – We are sourcing experts, offer competitive pricing and specialize in finding hard to find parts and reducing long deliveries.
  • One-Stop Shopping On Certified Hardware – We stock and source a full line of fasteners including Mil-Spec, DFARS compliant and other industrial products.
  • WBE/WOSB Woman Owned Certified Small Business – To meet your diversity & set-aside needs.

MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply. 

Leave a Reply