What is the correct way to refer to a lag, screw or bolt?

Hex Lag ScrewAlthough these terms are used interchangeably, lags should technically be referred to as a screw and not as a bolt.

A bolt is a fastener with machine thread that can accept a nut. A bolt is properly assembled and tightened by rotating the nut. A screw, on the other hand, is a fastener that is properly installed by rotating the head of the fastener. Since lags are not used with a nut and installed by turning the head of the fastener, the proper technical term would be “lag screw”. Lag screws can be provided with either a hex or square head.

A bolt is available with many different thread types, Unified National Coarse, Unified National Fine, 8 Unified National, Acme, and Metric. Both machine bolts and lag screws are made to the requirements of ASME B18.2.1. Lag screws are almost always used in wood applications.

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    looking for a quote for 1500 lag screws hex head 12mm X 150mm galv or zinc coated for wooden boat construction. + 1500 washers, Located in Norway.

    looking for a quote for 720 # 11434 lag screws hex head 1/2 ” X 7″ galv or zinc coated for wooden bridge construction.

    Project in S W Colorado

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