How do fasteners work?

Fasteners can be screws, bolts, nuts, washers, nails, togglers, hanger bolts, rivets and a lot more that I’m forgetting.

Photo by Robert Zunikoff on Unsplash

Fasteners are primarily used to clamp two parts together. Fasteners are fairwindfasteners.com usually shaped differently, come in different sizes, and have different names. As an example, a flat head wood screw, a hex nut, a hex head bolt, and a flat washer all have intuitive names. The names of these items, such as Escutcheon pins, castle nuts, carriage bolts or cheese head screws (which have nothing to do with Wisconsin football fans—I checked), come from a bygone era and make little sense today. The modern era has a better understanding of sizing conventions. Sizes are usually designated by numbers or measured in inches or millimetres. In order to streamline your efforts to gather the fasteners you need, it is helpful to know what you are looking for by name. This will help rule out significant portions of the fastener aisle.

Fastener parts

The naming convention for fasteners is usually determined by how the bin banks are organised or by the package labelling. Typically, fastener bins are organised by material, then by type, then by head style, then by drive type on the drawer faces. Within the drawers, the individual bins are labelled with diameter, thread pitch, and length.

The bin label below indicates that these machine screws have a diameter size of #12, a thread pitch of 24, and a length of 1 1/2″. In addition to offering a visual reference, a silhouette of a screw can be handy for smaller fasteners. In this case, the machine screw has a flat head and a Phillips drive. In addition to the silhouette above, this image is also on the drawer’s exterior to assist you in finding the right bin.

What’s the difference between stainless steel, bronze, and zinc plated steel?

A dock cart discussion almost always turns to what is the best material to use when boaters discuss the merits of oval head sheet metal screws vs. flat head wood screws (it happens). Stainless steel, bronze, chrome-plated brass? Stainless steel is generally considered to be the best material for fasteners of all kinds. Quite rightly so. A variety of stainless steels are available at a reasonable price and offer excellent corrosion resistance and strength (more on this below).

In the marine environment, bronze and plated or coated steels have a place. Due to its corrosion resistance even in the absence of oxygen, bronze is a great choice for applications below the waterline, and it is often the least noble metal on a boat—which means it can play well with other materials; as such, it is unlikely to galvanise with the materials it secures or to which it is near. For shaft coupling bolts and other engine components, coated graded steel is a better choice than stainless steel. The best choice for most applications, aside from engine applications, is still stainless steel. You should check the instructions provided with the hardware or equipment you are installing to find out what the manufacturer recommends.

Which stainless steel grade is best?

For fasteners, stainless steel comes in three types: 18-8, 304, and 316. To simplify things, remember that the higher the type number, the greater the corrosion resistance. 316 stainless steel is more corrosion resistant than 304 and 18-8 stainless steel is less corrosion resistant than 304.

In addition to corrosion resistance, boaters often overlook the strength costs associated with this extra protection. Each type of stainless steel has different tensile strengths due to its alloy composition. A corrosion-resistant fastener has a lower tensile strength than one that is not. Opting for the corrosion-resistant material will not affect the holding power in many cases since the difference is often minor. It can also be advantageous to choose a weaker material in other cases.

304 or 18-8 or 304 stainless steel may be a better choice for highly loaded hardware that is under a load in-line with the fasteners (a tensioned load). Stainless steel bolts are not suitable for shaft couplers due to their lower tensile strength, regardless of type: zinc coated grade 8 bolts are the best choice.