Name That Hardware

Hex-Head Screw

It’s been just more than a month since my backside found its way back into an editorial chair here at Popular Woodworking Magazine. We are about to wrap up the first issue since my return. That means the articles are in our binder and we read everything one additional time to make sure there are as few mistakes as possible before it goes to press then to you for your reading pleasure. (It’s your duty to find the one mistake we left in the magazine and that can only be accomplished if your read the entire issue from front to back.)

Reading binder is totally different for me this time around. My duties and responsibilities are different. But there are things that stay the same. As we read, we also discuss any concerns we find. Yesterday there were a few discussions, but the one that fascinated me the most was about hardware for a portable workbench top.

In the article text, the author, Christopher Schwarz, writes that the above-picture hardware is a hex-head bolt. Of course, with each round that label is challenged. We all call it a lag screw. Bob Lang and I say a bolt has a nut involved to make a connection and that a lag screw is what was used.

Via e-mail, Chris again defended his label and directed us to a home center to confirm – he used the term by which the piece was listed at the store at which he bought it. (The goal is to make it easy for readers to find the exact piece – be it screws, nails or drawer pulls – used in the article.) So check we did. Do you think you know the answer? Be careful.

Online at one store we found the terms “hex-head screw” and “lag screw” intermixed. At a second store, we found similar terminology and we found the hardware item pictured below.

Lag Bolt ?

Chris wasn’t wrong in how he listed the piece.

Is this what happens when store inventory is labeled by folks who don’t really know what the item is called? Or is this known as a hex-head bolt? Are the terms hex-head and lag, and bolt and screw interchangeable? Comments are open. Let’s hear your thoughts.

— Glen D. Huey

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67 thoughts on “Name That Hardware

  1. NoelNNY

    The Lady Megan hath not offered her wise words of what the ol’ bard would recount on the matter – could this topic be retitled “The Turning of the Screw” ?

    What say ye Fair Lady of Auburn Loc’s???

  2. Jeff Ward

    Having worked in retail for many years, I would suggest that if bin tags are evidence for terminology, there would be many more conflicts about proper names for things. Beyond terminology, it’s nearly as bad to assume that what is in the bin matches the tag.

    Ultimately, I’ve got to agree with Jack on this one. Lag bolt or lag screw? The only possible answer is yes.

  3. A Tinkers Dam

    I am a retired machinist (30+yrs) and a past instructor of manufacturing and engineering. I hung up my machinist career some years ago, retired and now pursue my serious woodworking “hobby”.

    Terminology / Nomenclature in threaded fastenters is very improtant in the field of manufacturing. The go-to source around the world is the Machinery’s Handbook” printed by Industrial Press. Another referance source are the Audell’s Manuals of old. I will provide (from Machinery’s Handbook) the distinctions between the threaded fasteners in question.
    “Differentation between Bolt and Screw:
    -A bolt is an externaly threaded fastener disigned for insertion through holes in assembled parts, and is normally intended to be tightened or released by torquing a nut.
    -A screw is an externally threaded fastener capable of being inserted into holes in assembled parts,of mating with a preformed internal thread or forming its own thread and of being tightened or released by torquing the head.”
    -An externaly threaded fastener that has a thread form which prohibits assembly with a nut having a straight thread of multiple pitch length is a SCREW. (Example: wood screws, tapping screws)
    -An externally threaded fastener that must be assymbled with a nut to perform its intended service is a BOLT.
    -An externally threaded fastener that must be torqued by its head into a tapped or other preformed hole to perform its intended service is a SCREW. (example square head set screw).
    Specification for manufacture of fasteners such as that pictured are found in the table “American National Standard Hex Lag Screws (ANSI B18.2.1-1981, R1992)

    The general definition of a “lag screw” is:
    lag screw
    (Miscellaneous Technologies / Building) a woodscrew with a square head
    [from lag3; the screw was originally used to fasten barrel staves] (lagging)
    Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003
    (The referance to “square head” stems from the original head form of a lag. Modern lags now are available with hex heads.)

    So this is a VERY long way to explain the the fastener in question is technically refered to as a “Hex Lag SCREW”. If it were to have a square head it would be refered to as a “Square Lag SCREW”.

    No such thing as a Lag BOLT, if threaded into a pre-threaded hole, it would simply be refered to as a Screw, Cap SCREW or Machine SCREW (that’s another long winded discussion).

    Sorry if I seem overly anal about the terminology but after many, many years of experiancing confusion when correct terminology is not used I have seen the benifits of using the correct terms to identify fasteners.

    If I may be so bold, the definative answer to your question is: The fastener shown is indeed a “Hex Head Lag SCREW”. Sorry Chris, but I will bow to you on all things “WOOD”.
    Mike W.

  4. chodgkin

    The Complete Illustrated Guide to Everything Sold in Hardware Stores, by Tom Philbin & Steve Ettlinger quite simply calls it “Lag Bolt (or Screw)”

    Their buying tip is “Lag screws are cheaper than carriage bolts, so if you have a choice, use a lag screw.”

    I’ve built a number of raised bed gardens, have used these extensively, and when I order them for delivery with the lumber I always order them as lag bolts and always get what I want.

  5. MikeyD

    Omitting the word “lag” and calling it a hex head bolt would lead one to believe it is the type that uses a nut. That’s the problem I have with the wording. It’s misleading.


    I am an old retired electric utility phart and specified may things for the construction crews where I got to know hardware. The lag screws (bolts) used by the utility `15 years ago were all square heads, like wise for Mark and those trying to hammer in a lag screw there are different threads for hammering in a lag screw. the link below is to a supplier of pole line hardware, scroll down to near the bottom of the page and several different types of lag screws (bolts) are shown.

    Various Trades have products that are unique to their needs but frequently used by other trades also and called by different names.

  7. rrich

    I’m an old phart and growing up on the water in Brooklyn, they were called Lag Bolts. (Stainless steel we would have killed for) Like many things, the name changes between the East and West coasts. Here on the West coast, the term Lag Screw seems to be more popular. So, what is your orientation, Left or Right?

    Generally speaking, when a hex head is attached to a threaded shaft, the term “Lag” also seems to be attached to almost anything except machine threads. One other interesting fact, McFeely’s seems to have far more “Lag Screws” than “Lag Bolts”.

    It appears that the non-machine thread threaded device fitted with a hexagonal head is somewhat lagging in an official definition. What more can one say?

      1. perldrivr

        Once, as a new member on a framing grew, I was sent to assist another crew member to install a deck rim joist on a house that was nearly completed. When we got to the job site my superior realized we did not have the wrench to turn in the lag screws, so I watched aghast as he drove the 3/8″ by 4″ lags with a 28 oz. framing hammer. Always wondered how that install held up.

  8. johnmoran

    It’s a screw – Chris is just being stubborn … for a change.

    If he was an engineer, he would call it a screw.

    Just because he’s a stubborn woodworker doesn’t mean it’s a bolt.

    tgoplin has already quoted the definitive test – Machinery’s Handbook.

    Give in Chris.

    Kind regards – John

    1. Megan FitzpatrickMegan Fitzpatrick

      For the record, Chris wasn’t really being stubborn – he said it was up to us. We just found it interesting/vexing that when one goes to purchase said item, it isn’t always correctly named – and that makes it harder for (inexperienced) readers to know what to buy. In the end, we decided to use the proper ASME term.

  9. lhowland

    I would always refer to that type of fastener as a lag screw. That differentiates the thread type from something used on a machine or my automobile. I would assume that the hex head just further defines it. But, I have never held a lag screw in my hand that had a philips head or a slotted head. Might be a little difficult to install.
    With respect to the packaging of these fasteners. Are we seeing a majority of these coming from overseas and the precise description we would use is muddied up by someone else attempting to translate a dictionary definition with their interpretation?

  10. tgoplin

    According to the Machinery’s Handbook you have a lag screw. If a fastener is normally intended to be tightened or released by a nut it is a bolt. If a fastener is inserted into a preformed thread or forms it’s own thread and can be tightened or released by torquing the head it is a screw. It goes on to say that an externally threaded fastener that has a thread form which prohibits assembly with a nut having a straight thread of mulitple pitch length is a screw (Example: wood screws, tapping screws.) An externally threaded fastener that must be assembled with a nut to perform its inteded service is a bolt. (Example: heavy hex structural bolt.) No offense to the kind folks at the hardware store but I’m going with the handbook.

  11. Jack

    Bolts, with machine type threads, are also referred to as ‘machine screws’.

    Screws (wood screws mainly, but near the point even ‘deck screws’) seem to have ‘tapered’ threads. Even sheet metal screws taper from either a blunt point (for use where there are pre-drilled and possibly threaded holes) or sharp point to ‘self thread’.

    It appears that hardware of various kinds are not universally known by a single name, plus regional names. At times it appears they are all regional names.

    So it is a lag bolt or lag screw? The correct answer is: Yes.

  12. hharr40

    In my experience “Bolts” have machine threads and “Screws” have the more agressive wood cutting threads. While a Bolt must have a mating threaded partner – nut or threaded hole, a Screw makes its own way into the material being fastened – albeit sometimes with a pilot hole to ease insertion.

    Perhaps the confusion occurs because the “Lag Bolt/Screw” has a machine bolt hex head but wood cutting threads whilst Wood Screws (with wood cutting threads) have provision to be driven by a “Screw Driver” as opposed to a Wrench. Now throw in the term “Machine Screw” – screwdriver head but machine threads – and we’ve quite a goulash of terminology.

    “A picture is worth a thousand words”

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