Home | Square ID Washers - Anti-Rotation Flat Washers with Square Bore
Square ID Washers - Anti-Rotation Flat Washers with Square Bore

Square ID Washers - Anti-Rotation Flat Washers with Square Bore

Showing 1–19 of 19 products

SKU OD Thickness Quantity

575-10-031

OD 0.197
Thickness 0.031
Quantity

575-11-005

OD 0.245
Thickness 0.005
Quantity

575-11-010

OD 0.245
Thickness 0.01
Quantity

575-11-020

OD 0.245
Thickness 0.02
Quantity

575-12-030

OD 0.28
Thickness 0.03
Quantity

575-13-031

OD 0.375
Thickness 0.031
Quantity

575-14-025

OD 0.497
Thickness 0.025
Quantity

575-15-062

OD 0.5
Thickness 0.062
Quantity

575-16-031

OD 0.561
Thickness 0.031
Quantity

575-17-020

OD 0.625
Thickness 0.02
Quantity

575-18-031

OD 0.88
Thickness 0.031
Quantity

575-19-030

OD 0.312
Thickness 0.03
Quantity

575-20-048

OD 0.5
Thickness 0.048
Quantity

575-21-060

OD 0.68
Thickness 0.06
Quantity

575-22-060

OD 0.7
Thickness 0.06
Quantity

575-23-060

OD 0.937
Thickness 0.06
Quantity

575-24-060

OD 1.0
Thickness 0.06
Quantity

575-25-060

OD 1.125
Thickness 0.06
Quantity

575-26-060

OD 1.25
Thickness 0.06
Quantity

Square ID Washer Frequently Asked Questions

Below are answers to some of the most common questions about square ID washers.

What are square ID washers?
Square ID washers are flat washers with a square inner bore rather than a round hole. The square bore is designed to fit over square-necked fasteners such as carriage bolts, preventing the fastener from rotating during tightening without requiring a wrench on the bolt head. They are widely used in woodworking, construction, and structural fastening applications where carriage bolts are specified. Superior Washer manufactures square ID washers in a range of sizes and materials.

Why use a square ID washer instead of a round ID washer?
Square ID washers are used specifically with square-necked or square-headed fasteners. When a carriage bolt is pulled through a wood or panel substrate, its square neck embeds in the material and prevents rotation. The square ID washer fits around the square neck and distributes the clamping load across a larger bearing surface. A round ID washer would not engage the square neck and would allow rotation during assembly.

What applications use square ID washers?
Square ID washers are used in deck construction, timber framing, furniture manufacturing, playground equipment, agricultural structures, and any application using carriage bolts or square-necked fasteners. They are also used in electrical and mechanical assemblies where a square-profile spacer or insulating washer with a square bore is required.

What materials are square ID washers available in?
Square ID washers are produced in steel, stainless steel, brass, aluminum, and non-metallic materials including nylon and fiber. Contact us to specify your required material.

Can you produce custom square ID washers?
Yes. We manufacture custom square ID washers to your bore size, OD, and thickness specifications. Contact us via the Quick Quote form or call NY (631) 273-8282 or SC (803) 366-3250.

Are your square ID washers made in the USA?
Yes. All square ID washers are manufactured in the United States under our ISO 9001:2015 certified Quality Management System at our Hauppauge, NY and Rock Hill, SC facilities.

Need a square OD instead of a square bore? Browse the full flat washers catalog to see all shapes and materials available.