McMaster-Carr logo
    Forward
    Enter e-mail addresses in the fields below
    Message
    Cancel
    Print
    How can we improve?
    Comments
    E-mail address (if you would like a response)
    42 Products

    Thin-Heavy-Profile Nylon-Insert Locknuts
    3D CAD models available

    Image of Product. Front orientation. Locknuts. Thin-Heavy-Profile Nylon-Insert Locknuts.
    About half the height of standard-profile locknuts and 10% wider, these fit in spaces with low clearance and handle heavier loads by distributing them over a larger area. You can also use them as jam nuts by threading them against a hex nut to hold it in place. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.
    High-Strength Steel
    Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Black-Phosphate-Coated Steel—The dark coating creates both a finished appearance and a barrier against rust that's comparable to zinc yellow-chromate plating.
    Steel—Best for dry environments since moisture will cause these nuts to rust.
    Thread
    Size
    Wd.
    Ht.
    Fastener Strength
    Grade/Class
    Insert Max.
    Temp., ° F
    Each
    Black-Phosphate-Coated Steel
    1 1/4"-12
    		2"1 7/64"ASTM Grade C
    		25000000000000000
    1 1/2"-12
    		2 3/8"1 5/16"ASTM Grade C
    		25000000000000000
    1 3/4"-12
    		2 3/4"1 15/32"ASTM Grade C
    		25000000000000000
    2"-12
    		3 1/8"1 43/64"ASTM Grade C
    		25000000000000000
    2 1/4"-12
    		3 1/2"1 15/16"ASTM Grade C
    		25000000000000000
    2 1/2"-12
    		4"2 3/16"ASTM Grade C
    		25000000000000000
    2 3/4"-12
    		4"2 3/16"ASTM Grade C
    		25000000000000000
    3"-12
    		4 1/2"2 41/64"ASTM Grade C
    		250000000000000000
     
    Steel
    1 1/8"-12
    		1 7/8"1"ASTM Grade C
    		25000000000000000
    1 3/8"-12
    		2 13/64"1 3/16"ASTM Grade C
    		25000000000000000
     
    Low-Strength Steel
    Rated Grade 2, Class 6, or lower, these locknuts are about half as strong as medium-strength steel nuts. Use them with screws that have a similar strength rating to avoid stripping threads during installation.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Black-Corrosion-Resistant-Coated Steel—These nuts combine a finished appearance with the rust resistance of stainless steel. The coating has been tested to extreme standards, including 1,000 hours of salt spray resistance, to hold up in wet and outdoor environments. Also known as black luster.
    Thread
    Size
    Wd.
    Ht.
    Insert Max.
    Temp., ° F
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    1/4"-20
    		1/2"9/32"250100000000000000000
    5/16"-18
    		9/16"5/16"25010000000000000000
    3/8"-16
    		11/16"13/32"2505000000000000000
    1/2"-13
    		7/8"17/32"2502500000000000000
    5/8"-11
    		1 1/16"39/64"2501000000000000000
    3/4"-10
    		1 1/4"45/64"2501000000000000000
    1"-8
    		1 5/8"57/64"25010000000000000
    1 1/4"-7
    		2"1 7/64"25010000000000000
     
    Black-Corrosion-Resistant-Coated Steel
    1/4"-20
    		1/2"9/32"25050000000000000
    5/16"-18
    		9/16"5/16"25050000000000000
    3/8"-16
    		11/16"13/32"25010000000000000
    1/2"-13
    		7/8"17/32"25010000000000000
     
    Corrosion-Resistant Stainless Steel
    18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    316 Stainless Steel—Our most corrosion-resistant nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread
    Size
    Wd.
    Ht.
    Insert Max.
    Temp., ° F
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    1/4"-20
    		1/2"9/32"25025000000000000000
    5/16"-18
    		9/16"5/16"2502000000000000000
    3/8"-16
    		11/16"13/32"2501000000000000000
    1/2"-13
    		7/8"17/32"25010000000000000
    5/8"-11
    		1 1/16"5/8"25010000000000000
    3/4"-10
    		1 1/4"45/64"250100000000000000
    1"-8
    		1 5/8"59/64"250100000000000000
     
    316 Stainless Steel
    3/8"-16
    		11/16"13/32"25010000000000000
    1/2"-13
    		7/8"17/32"25010000000000000
    5/8"-11
    		1 1/16"39/64"25010000000000000
    3/4"-10
    		1 1/4"45/64"250100000000000000
     

    Thin-Heavy-Profile Flex-Top Locknuts for Heavy Vibration
    3D CAD models available

    Image of Product. Front orientation. Locknuts. Thin-Heavy-Profile Flex-Top Locknuts for Heavy Vibration.
    About two-thirds the height of standard flex-top nuts and 10% wider, these fit in spaces with low clearance and handle heavier loads by distributing them over a larger area. Because of the thin profile, you can also use them as jam nuts by threading them against a hex nut to hold it in place. The top section expands to grip the screw on all sides for a stronger hold than both nylon-insert and distorted-thread locknuts. As a result, they're suitable for use in equipment with constant, vigorous vibration, such as engines. These locknuts are reusable a handful of times, but the holding power decreases with each use.
    Steel
    These locknuts have equivalent strength to Grade 8 and Class 10 steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Cadmium-Plated Steel—These locknuts have good lubricity to thread on smoothly and ease installation. The plating also creates a barrier against rust that's comparable to zinc-yellow-chromate plating.
    Thread
    Size
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    Cadmium-Plated Steel
    1/4"-20
    		1/2"7/32"25000000000000000
    5/16"-18
    		9/16"17/64"100000000000000
    3/8"-16
    		5/8"9/32"1000000000000000
    7/16"-14
    		3/4"21/64"10000000000000
    1/2"-13
    		13/16"21/64"500000000000000
    5/8"-11
    		1"13/32"10000000000000
    3/4"-10
    		1 1/8"27/64"100000000000000
    7/8"-9
    		1 5/16"31/64"100000000000000
    1"-8
    		1 1/2"37/64"100000000000000
     
    back to top