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Simpson Anchors - SMSA Machine Screw Anchors

  • Tuesday, September 30, 2008

    Purchase Machine Screw Anchors

    Simpson Strong-Tie, Inc's concrete anchor division is known as Strong-Tie Anchor Systems® and their single machine screw anchor is named the SMSA. The generic name for this concrete anchor is the single expansion anchor. The SMSA machine screw anchor has a single plug that expands the anchor when a bolt is threaded into it. SMSA machine screw anchors are made from corrosion resistant die cast material Zamac 3.

    SMSA Federal Specifications

    The SMSA machine screw anchor meets federal specifications A-A-1923A, Type 2.

    SMSA Base Material

    SMSA machine screw anchors are versatile because they can be used in solid concrete, brick, cement block and grout filled block.

    SMSA Diameter

    The SMSA anchor is designated by the internal thread diameter of the anchor and is available in four diameters that have all national coarse threads: 1/4”-20, 5/16”-18, 3/8”-16. 1/2”-13. Concrete Fasteners, Inc. stocks and sells the single expansion anchor in the 5/8” and 3/4” diameter.

    SMSA Hole Diameter

    The diameter of the hole required to be drilled in the base material is equal to the outside diameter of the SMSA machine screw anchor. The hole must be drilled using a hammer drill with carbide tipped bit that meets ANSI standards in order to ensure a matched tolerance hole with the anchor. The 1/4” SMSA requires a 1/2” hole, the 5/16” SMSA requires a 5/8” hole, the 3/8” requires a 5/8” hole and the 1/2” requires a 7/8” hole.

    SMSA Hole Depth

    SMSA should be embedded as a minimum the length of the anchor in order that the top of the anchor is flush with the surface of the base material. Each diameter of SMSA anchor comes in only one length: the 1/4” SMSA is 1-3/8” long, 5/16” is 1-5/8” long, 3/8” is 1-5/8” long and the 1/2” is 2-1/2” long. Deeper embedment into the base material may increase holding values.

    SMSA Concrete Thickness

    The thickness of the concrete should be a minimum of 1-1/2 times the embedment depth of the anchor in the concrete. For example, if the 1/2” diameter SMSA machine screw anchor is being placed in concrete then the concrete must be at a minimum 3-3/4” thick (1-1/2 x 2-1/2”).

    SMSA Bolt Length

    The length of the bolt required is equal to the thickness of the material being fastened plus the depth SMSA machine screw anchor being embedded into the concrete. The bolt must be long enough so that a minimum of 2/3 of the threads are engaged.

    SMSA Product Information

    Item #

    Anchor Size

    Drill Bit Size

    Embedment Depth

    Box Quantity


    1/4” -20





    5/16” - 18





    3/8” - 16





    1/2” - 13




    SMSA Installation

    Important: The hole size in the base material is critical. If the hole is oversized then the anchor may not set properly and the holding values will be reduced

    1. Drill a hole in the base material, using a drill in the hammer and rotation mode with an ANSI standard carbide bit that matches the correct diameter of the hole required for the SMSA machine screw anchor being installed. Drill the hole at least as deep as the length of the anchor so that when the anchor is inserted into the hole, the lip of the anchor body is flush with the surface of the base material. For a flush mounting application, the hole should be drilled 1/8” deeper than anchor length to allow for dust to settle that is created by the installation of the anchor.

    2. Clean the hole of all dust that was created during the drilling operation. Using compressed air, a vacuum and a wire brush will accomplish this.

    3. Place the anchor in the hole with the single expander cone of the SMSA machine screw anchor going in first. Tap lightly with a hammer until the lip of the anchor is flush with the surface of the base material.

    4. Line up the hole of the fixture to be fastened over the SMSA machine screw anchor and insert the bolt through the fixture and into the SMSA machine screw anchor. Turn the bolt clockwise until it is tight in order to expand the SMSA anchor while making sure that a minimum of 2/3 of the threads of the SMSA machine screw anchor are engaged.

    Purchase Machine Screw Anchors


    Always use personal protective equipmentAs with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.

    Article Written By:
    Mike Pistorino, Vice-President Operations





    Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.

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