Description
One-Way Security Chicago Screw Sizes & Specifications
The charts below list standard one-way security Chicago screw and barrel nut sizes, including thread size, post length, screw length, shoulder style and dimensional specifications. Available UNC thread sizes include #8-32, #10-24, 1/4-20 and 5/16-18.
Select the required thread size, post length and screw style for your RFQ. Size and material availability varies by configuration. Custom post lengths, screw lengths and security fastener specifications are also available for OEM production.
THREAD SIZE(UNC) |
Length / L±0.01 |
Body Dia / D±0.004 |
Head Dia / A±0.008 |
Head Height / H±0.011 |
Thread Depth / G±0.02 |
| UNC 10-24 | 0.5 | 0.245 | 0.4375 | 0.12 | 0.37 |
| UNC 10-24 | 0.625 | 0.245 | 0.4375 | 0.12 | 0.5 |
Type A: Extended Shoulder
Extended-shoulder one-way screws provide additional unthreaded shoulder length for applications requiring greater spacing, alignment or material engagement.
THREAD SIZE |
Shoulder Type |
Length / L |
Shoulder / L1 |
Body Dia / D1 |
Head Dia / A |
Head Height / H |
| UNC 10-24 | Type A | 1.06 | 0.27 | 0.25 | 0.437 | 0.12 |
| UNC 10-24 | Type A | 1.19 | 0.27 | 0.25 | 0.437 | 0.12 |
| UNC 10-24 | Type A | 1.31 | 0.27 | 0.25 | 0.437 | 0.12 |
Type B: Standard Shoulder
Standard-shoulder one-way screws provide a shorter shoulder for common panel, partition and hardware assemblies.
THREAD SIZE(UNC) |
Shoulder Type |
Length / L±0.01 |
Shoulder / L1±0.008 |
Body Dia / D1±0.004 |
Head Dia / A±0.008 |
Head Height / H±0.011 |
| UNC 10-24 | Type B | 0.5 | 0.13 | 0.25 | 0.437 | 0.12 |
| UNC 10-24 | Type B | 0.75 | 0.27 | 0.25 | 0.437 | 0.12 |
| UNC 10-24 | Type B | 0.937 | 0.27 | 0.25 | 0.437 | 0.12 |
Type C: No Shoulder
No-shoulder one-way screws are available for applications requiring threads closer to the underside of the head. Custom screw lengths may be manufactured for OEM and production requirements.
What Are One-Way Security Chicago Screws?
One-way security Chicago screws are two-piece tamper-resistant fasteners consisting of an internally threaded female post and a matching male screw. They securely clamp materials between the two heads while maintaining a low-profile, finished appearance on both sides.
These fasteners are also known as one-way barrel nuts and screws, security binding posts, tamper-resistant Chicago screws, security sex bolts, one-way female posts or security screw posts.
The one-way drive is designed so that a standard flat-blade screwdriver can turn the fastener in the installation direction. The sloped drive surfaces resist engagement in the reverse direction, helping discourage unauthorized removal, theft and tampering.
Why Use a One-Way Security Drive?
One-way security drives are suitable for permanent or infrequently serviced assemblies installed in publicly accessible locations.
Benefits include:
- Straightforward installation with a standard flat-blade driver
- Resistance to unauthorized removal
- Clean, low-profile appearance
- Secure two-piece through-panel connection
- Multiple post and screw configurations
- Standard and custom production sizes
- No proprietary installation bit required
Because the drive is intentionally difficult to reverse, confirm that future disassembly is not required before installation.
Thread Sizes & Lengths
One-way security Chicago screws are available in standard UNC thread sizes:
- #8-32 One-Way Security Chicago Screws
- #10-24 One-Way Security Chicago Screws
- 1/4-20 One-Way Security Chicago Screws
- 5/16-18 One-Way Security Chicago Screws
Post length, screw length, shoulder configuration and dimensional availability vary by thread size. Refer to the charts above for standard configurations.
If the required size is not listed, custom thread sizes, female post lengths and matching one-way screw lengths may be available for OEM production.
Materials & Finishes
One-way security barrel nuts and screws are available in:
- Zinc-Plated Steel
- Aluminum
- Brass
- Stainless Steel 18-8
- Stainless Steel 316
Zinc-plated steel provides economical performance for general industrial and interior applications. Stainless steel is available for applications requiring improved corrosion resistance, public hardware or outdoor exposure.
Brass and aluminum may be selected for appearance, reduced weight or material compatibility. Material and finish availability varies by thread size, length, style and production quantity.
Installation
Insert the female threaded post through the properly sized mounting hole. Align the matching one-way screw from the opposite side and start the thread by hand.
Tighten the screw clockwise using a flat-blade screwdriver until the assembly is secure. Avoid overtightening, particularly when fastening plastic, composite, laminated or decorative materials.
Before installation:
- Confirm the correct thread size.
- Select a post and screw combination suitable for the total material thickness.
- Verify adequate thread engagement.
- Confirm the required shoulder style.
- Make sure future routine disassembly will not be required.
Typical Applications
One-way security Chicago screws are commonly used in assemblies requiring tamper resistance and a clean finished appearance.
Typical applications include:
- Public restroom partitions
- Commercial bathroom hardware
- Architectural panels
- Door and partition hardware
- Public signage and displays
- Electrical and equipment enclosures
- Furniture and cabinetry
- Safety guards and protective fixtures
- Schools and public facilities
- Transportation and public-access equipment
- Retail fixtures and loss-prevention installations
Factory-Direct Supply & Custom Options
Imperial Rivets & Fasteners supplies factory-direct one-way security Chicago screws, security barrel nuts and tamper-resistant binding posts for commercial, architectural and OEM applications.
Standard sizes are stocked in our U.S. warehouse for fast shipment. Extended-shoulder, standard-shoulder and no-shoulder configurations are available, along with multiple materials and finishes.
Custom thread sizes, female post lengths, screw lengths, shoulder dimensions, materials and finishes may be manufactured for production requirements.
Select a standard configuration from the specification charts and add it to your RFQ. If the required size is not listed, contact our sales team for custom production options.
Questions or Custom Requirements?
Contact our sales team for stock availability, bulk pricing, samples or custom manufacturing.
Email: sales@imperialrivet.com
Phone: (630) 964-0208
