The best 1/4-20 set screw depends mainly on the length needed to secure your part. For a short reach, choose the 1/4-inch option; for deeper engagement, consider the 1/2-inch or 3/4-inch screws. The assortment kit is best when you need several lengths. The fifth listed item is a tamper-resistant machine screw, not a set screw, so it is included only as a distinction to help prevent a mismatched purchase.
| Product | Best For | Length Options |
|---|---|---|
| 304 Stainless Steel Set Screws | Short-reach fastening | 1/4 inch |
| 304 Stainless Steel Set Screws | Deeper engagement | 1/2 inch |
| Eight-Size Set Screw Kit | Multiple lengths | 3/16 to 1 inch |
| 304 Stainless Steel Set Screws | Longer reach | 3/4 inch |
| Frienda Security Machine Screws | Security fastening, not set-screw use | 1-1/2 inches |
1/4-Inch 304 Stainless Steel Set Screws
This 50-piece pack contains 1/4-20 cup-point socket set screws measuring 1/4 inch long. The screws are made from 304 stainless steel and use an internal hex drive. A 1/8-inch Allen wrench is included, and the headless design allows the screw to sit flush with or below a surface when installed.
Best for: Buyers who already know they need a short 1/4-inch screw and want a supply of matching fasteners. It was selected as the shortest dedicated set-screw option in the list. The listing describes the steel as corrosion-resistant and suitable for varied conditions, but does not specify a particular application load.
Consider: The fixed length may be too short when the threaded hole or required engagement is deeper. Confirm the needed length before ordering.
1/2-Inch 304 Stainless Steel Set Screws
This pack includes 50 cup-point 1/4-20 set screws, each 1/2 inch long, plus a 1/8-inch Allen wrench. The screws are listed as 304 stainless steel, with an internal hex socket and headless profile for installation at or below the surface.
Best for: Repairs that need more screw length than the 1/4-inch option provides. Choose this if a half-inch fastener matches the depth of your threaded hole and the assembly. It offers the same stated material and included tool as the shorter pack, but with greater length.
Consider: A longer screw is not automatically a better fit. Avoid choosing it if it could bottom out in the hole or extend farther than the assembly allows.
Eight-Size 1/4-20 Set Screw Kit
This 50-piece assortment includes eight lengths: 3/16, 1/4, 5/16, 3/8, 1/2, 5/8, 3/4, and 1 inch. The screws are made from 304 stainless steel and have cup points. The listing also describes deep threads, even pitch, and a smooth surface; an Allen key is included.
Best for: Buyers who are replacing an unknown screw or expect to need several lengths for different repairs. It was selected for versatility rather than quantity of any single size. Listed potential uses include handles, fixtures, racks, machinery, and instruments.
Consider: The assortment contains only two 1-inch screws and four each of the 5/8- and 3/4-inch sizes. It may not suit a project that needs many pieces of one length.
3/4-Inch 304 Stainless Steel Set Screws
This pack provides 50 1/4-20 cup-point set screws at 3/4 inch long, along with a 1/8-inch Allen wrench. The product information identifies the material as 304 stainless steel. Like the other dedicated packs, these are headless screws with an internal hex drive.
Best for: Buyers who need a longer set screw and want multiple pieces of one size. Choose it over the 1/2-inch pack when the required threaded engagement calls for the additional quarter inch, after checking hole depth and fit.
Consider: The package supplies one length only. Choose the assortment instead if the correct length is uncertain or may vary across repairs.
Frienda Tamper-Resistant Machine Screws
This 50-piece package contains 1/4-20 by 1-1/2-inch button-head security machine screws made from 18-8 (304) stainless steel. It includes a matching T-27 security bit. The pin-in drive is designed to resist removal with standard screwdrivers, and the listing describes use for license plates, wall plates, and public or outdoor fixtures.
Best for: Buyers specifically seeking tamper-resistant machine screws. This item is included to clarify a common naming distinction, not as a substitute for a set screw.
Consider: It has a protruding button head and a security drive, rather than the headless internal-hex configuration described for the set screws above. Avoid this product if you need a set screw that sits flush or below a surface.
Buying Guide: How to Choose a 1/4-20 Set Screw
What Does 1/4-20 Mean?
In this listing context, 1/4-20 identifies a 1/4-inch nominal thread diameter with 20 threads per inch. Match this thread designation to the existing threaded hole. A screw with the wrong thread may not engage properly, even if its length is correct.
Which Length Should You Choose?
Measure the available threaded depth and the length needed to hold the part in place. Compare the 1/4-, 1/2-, and 3/4-inch single-size packs when you know the required length. The assortment covers eight lengths from 3/16 to 1 inch when the correct size is uncertain. Check that the screw will not bottom out or protrude where it should remain recessed.
Does the Point and Drive Matter?
The dedicated set-screw packs described here use cup points and internal hex sockets. The listed wrench size for the single-size packs is 1/8 inch. Confirm the drive tool fits securely before installation to reduce the chance of damaging the socket. The security machine screw has a different pin-in drive and requires its included T-27 security bit.
Is Stainless Steel the Right Material?
The set-screw listings identify their material as 304 stainless steel; the security screws are listed as 18-8 (304) stainless steel. The descriptions emphasize corrosion resistance, but do not provide application-specific load limits. For equipment with defined strength, exposure, or safety requirements, check the fastener specifications needed for that use.
Frequently Asked Questions
Are these set screws all 1/4-20?
The four dedicated set-screw products are listed as 1/4-20. The Frienda security machine screws are also listed as 1/4-20, but they are a different fastener style.
What length options are available?
The individual packs are 1/4, 1/2, and 3/4 inch long. The assortment includes lengths from 3/16 inch through 1 inch.
Does each set-screw pack include a wrench?
The three single-size packs specify a 1/8-inch Allen wrench. The assortment listing says Allen keys are included but does not state the key size in the supplied details.
Can a security machine screw replace a set screw?
Not when the job requires a headless screw that sits flush or below the surface. The security screw has a button head and a pin-in drive, so choose it only when those features suit the application.