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Hex Lag Screw

Hex lag screws, also called lag bolts, are used in wood construction. The threads on lag bolts are designed to embed into the wood, rather than relying on a nut to secure the connection. A pilot hole is typically pre-drilled in the wood before inserting the bolt, and must be sized to allow the threads to embed tightly and securely in the wood. Square lag screws are also available and are used for aesthetic purposes to provide a rustic look.

MANUFACTURING

Portland Bolt manufactures lag screws from 1/2" diameter through 1-1/2" diameter in most ASTM, AASHTO, and SAE specifications. Special tooling can be created to produce nonstandard head dimensions or bolt heads with your company’s name and/or logo.

One should consider longer than standard thread lengths for lag screws which are extremely long. Unless otherwise specified, Portland Bolt manufactures nonstandard lag screw with a thread length of one-half the bolt length plus 1/2" regardless of the length of the bolt. Unless otherwise specified, nonstandard lag screws manufactured by Portland Bolt will possess a semi-cone point rather than a gimlet or cone point. A full point is unnecessary since a pilot hole nearly as large as the root diameter of the lag screw will need to be drilled prior to installation. Additionally, a gimlet point is designed for small diameter screws so they can be installed without a pilot hole. Lag screws in diameters listed in the above table do not require a gimlet point since too much torque would be required to install the large screws without drilling a pilot hole first. Without a pilot hole, the heads of the screws will often break before the lag is properly installed.

STOCK

Diameters: 1/2" - 3/4"
Lengths: 18" maximum
Origin: Import
Finish: Black and hot-dip galvanized

STANDARD THREAD LENGTH

The minimum thread length shall be equal to one-half the nominal screw length plus 1/2" or 6”, whichever is less.

Note: Hex lag screws larger than 3/4" in diameter and all square lag screws are rarely available in the marketplace as a stock item.

Bolt
Diameter		 D F H Threads
Per
Inch		 Thread Dimension
Body Diameter Width Across
Flats		 Head
Height
Max Min Pitch
Flat
At
Root		 Depth
of
Thread		 Root
Diameter
3/8 0.388 0.360 9/16 1/4 7 0.143 0.062 0.055 0.265
1/2 0.515 0.482 3/4 11/32 6 0.167 0.072 0.064 0.371
5/8 0.642 0.605 15/16 27/64 5 0.200 0.086 0.077 0.471
3/4 0.768 0.729 1-1/8 1/2 4-1/2 0.222 0.096 0.085 0.579
7/8 0.895 0.852 1-5/16 37/64 4 0.250 0.108 0.096 0.683
1 1.022 0.976 1-1/2 43/64 3-1/2 0.286 0.123 0.110 0.780
1-1/8 1.149 1.098 1-11/16 3/4 3-1/4 0.308 0.133 0.119 0.887
1-1/4 1.277 1.223 1-7/8 27/32 3-1/4 0.308 0.133 0.119 1.012
1-3/8 1.404 1.346 2-1/16 29/32 3 0.333 0.143 0.128 1.119
1-1/2 1.531 1.469 2-1/4 1 3 0.333 0.143 0.128 1.244

Dimensions per ASME B18.2.1 1996