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)
    4 Products
    About Threaded Inserts
    industrial info icon

    Choose the right threaded insert for your application and learn how to install it securely.

    Helical Threaded Inserts

    Image of Product. Pronged. Bottom orientation. Threaded Inserts. Helical Threaded Inserts, Pronged.

    Pronged

    Restore, reinforce, or create threads in metal. The tough coils on these inserts expand once installed to anchor in a tapped hole. Also known as Heli-Coil inserts, they're often used in engine heads and machinery housings where strong connections are critical. Unlike threadlocking inserts, you can remove and reuse them without them losing their strength.
    Installation requires a drill bit, a helical insert tap, and an installation tool.
    Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.
    Inserts
    Through-Hole
    Taps
    Closed-End
    Hole Taps
    Installation
    Tools
    Thread
    Size
    Installed
    Lg.
    Drill Bit
    Size
    For Max.
    Hole Dia.
    Pkg.
    Qty.
    Pkg.
    Each
    Each
    Each
    Pronged
     
    18-8 Stainless Steel
    1 3/4"-8
    		2.625"1 3/4"
    		1.750"192335A11900000092335A319000000091709A330000000092450A194000000
     

    Helical Insert Taps

    Image of Product. Front orientation. Taps. Helical Insert Taps.
    Match the size of helical inserts so they fit tightly when installed in the hole.
    High-Speed Steel—These taps resist heat and wear to stay sharp.
    Plug Chamfer—Our go-to chamfer type. With a longer taper than a bottoming chamfer, they are easier to turn but won't thread as close the bottom of a hole.
    Bottoming Chamfer—Cut all the way to the bottom of blind holes with taps that have the shortest taper. Since these require the most force to turn, they’re often used to finish holes started by taper- or plug-chamfer taps.
    Drill Bit
    Plug Chamfer
    Bottoming
    Chamfer
    For Insert
    Size
    Thread
    Lg.
    Overall
    Lg.
    For Insert
    Thread Type
    No. of
    Flutes
    Size
    Decimal Size
    Equiv.
    Shank
    Type
    Each
    Each
    High-Speed Steel
     
    Uncoated
    1 3/4"-8
    		3 5/8"7 1/4"UN
    		61 3/4"
    		1.75"Square92335A3190000000———0
    1 3/4"-8
    		3 3/4"7 1/4"UN
    		61 3/4"
    		1.75"Square———091709A3300000000
     

    Helical Threaded Insert Installation and Prong Break-Off Tools

    Image of Product. Front orientation. Threaded Insert Installation Tools. Helical Threaded Insert Installation and Prong Break-Off Tools, T-Handle.

    T-Handle

    Install helical inserts and break off prongs with one tool and a hammer strike. These tools have a slot that grips your insert’s prong for turning both left- and right-hand threads. Slide an insert onto these tools and drive them a quarter-turn to half-turn below the material’s surface. Then, strike the end of the tool with a hammer to break off the prong. These tools work with pronged helical inserts.
    For Thread Size
    Handle
    Style
    Each
    1 1/2"-12, 1 3/4"-8, 1 5/8"-8, M39 × 2 mmT-Handle92450A194000000
     
    back to top