Fastener Chart

Great find, Bob.

I wonder about some of their treminology. I hear all the time the term "Lag bolt" but to me a "BOLT" requires a NUT or it's a screw. Now the "machine screw" can be either a screw (if it goes in a threaded hole) or a bolt if it has a nut on it. But the "LAG" thing hasent a chance of putting a nut on it, therefore it's a SCREW. One other minor point is the washer that they called "finish" I have used those for over 50 years and they have always been "cup washers". Otherwise a good compendium. ...lew...

Lew:

There does seem to some ambiguity and overlap of terms in the industry.

The lead screw in lathes used the saddle as a "nut", and the ball screws used in CNC's also use "ball nuts", so you'd think that they might be called "lead bolts" or "ball bolts", eh?

Here's an excerpt from Wik on screws (it touches on lag bolts):

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Carriage bolt with square nut. Structural bolt DIN 6914 with DIN 6916 washer and UNI 5587 nut.A universally accepted distinction between a screw and a bolt does not exist.

In common usage the term screw refers to smaller (less than 1/4 inch) threaded fasteners, especially threaded fasteners with tapered shafts used in un-threaded substrates and the term bolt refers to larger threaded fasteners that are designed to be used with nuts or in tapped holes. The term machine screw is commonly used to refer to smaller threaded fasteners that are used with nuts or in tapped holes. The term lag bolt (also known less commonly as a lag screw) is used to refer to larger threaded fasteners with tapered shafts.

Various methods of distinguishing bolts and screws exist or have existed. These methods conflict at times and can be confusing. Old SAE and USS standards made a distinction between a bolt and a cap screw based on whether a portion of the shaft was un-threaded or not. Cap screws had shafts that were threaded up to the head and bolts had partially threaded shafts. Today a bolt that has a completely threaded shaft might be referred to as a tap bolt.

ASME B18.2.1 defines a bolt as "an externally threaded fastener designed for insertion through the holes in assembled parts, and is normally intended to be tightened or released by torquing a nut." Using this definition to determine whether a particular threaded fastener is a screw or a bolt requires that an assumption be made about the intended purpose of the threaded fastener, and as a practical matter does not seem to be followed by most threaded fastener manufacturers. It also conflicts with common usage such as the term "head bolt", which is a threaded fastener that mates with a tapped hole in an engine block and is not intended to mate with a nut.

It is possible to find other distinctions than those described above, but regardless of the particular distinction favored by an individual or standards body the use of the term screw or bolt varies. More specific terms for threaded fastener types that include the word screw or bolt (such as machine screw or carriage bolt) have more consistent usage and are the common way to specify a particular kind of fastener.

The US government made an effort to formalize the difference between a bolt and a screw, because different tariffs apply to each. The document seems to have no significant effect on common usage and does not eliminate the ambiguous nature of the distinction for some fasteners. The definition is available online. ======================================================================

There is MUCH more juicy screw/bolt info on that site.

Has anyone seen a chart recommending drill sizes to use with sheet metal screws and self tappers?

That was too easy. Thank you

Lew,

I've only used them for 45 years so I guess you have the upper hand. But we always called them finishing washers. Walk into a large hardware store ( not HD or Lowes ) and ask for a cup washer and when you get a blank stare ask for a finishing washer.

A cup washer for me has a vertical wall that you snap a decorative cap onto.

Just my 2 cents, Will

In one shop I used to visit, they were known as "beauty rings". Gerry :-)} London, Canada