Fasteners are a subject that a lot of people are all over the place on. There are industry-specific terms, but most people use slang or regional terms. I am going to outline the industry-specific terms so we can all be on the same page, maybe making the finding and supplying of fasteners easier. I am going to limit this to the fasteners that we use commonly to avoid confusion.
I will be adding to this over time, doing it all at once is difficult and time-consuming. If there’s something you don’t see that you want to see, let me know. If you have questions I am happy to answer them.
The terms ‘screw’ and ‘bolt’ are sometimes used interchangeably, however, in simple terms, a bolt passes through a material and into a nut on the other side, whereas a screw threads directly into a material. Almost all of the screws we use are socket screws, this means they use a hex/allen tool to tighten and loosen. There are a few other commonly used types that I will cover later.
With that out of the way, let’s begin with Head Types, sometimes called Style Types.
*Ignore the slots in the graphic above, all we are concerned with is the head shape.
- Socket Cap bolts are great for motors and motor mounts as they are strong, have a lot of surface area to torque against and are available in multiple finishes.
- Pan head bolts are great to have in your kit as they have a small exposed surface area and are less likely to impede the travel of other objects. They are great for motors, motor mounts, panel mounts, etc.
- Button head bolts are great to have in your kit as they have a small exposed surface area and are less likely to impede the travel of other objects. They are great for motors, motor mounts, panel mounts, etc.
- Flat bolts, sometimes called Chamfered head bolts are commonly used as truck mounting hardware. They are great for that purpose as they fit flush with the deck.
- Hex bolts are really NOT used a lot in esk8, but I have used them before and they are the most commonly used bolts in the world. I include them as a reference only.
Let’s move on to Nut Types.
All of the nuts we use are hex nuts, the question is what type.
- Hex nuts are just that, hex shaped nuts with no frills, no extras. They come in a variety of materials (we will discuss this later) and finishes.
- Nylon Insert Lock nuts, AKA Nylok Nuts, are awesome. They stay where you put them & are very unlikely to lose grip.
3… Jam nuts are the same as hex nuts, only smaller in height. These are great for places where clearance is an issue. - Nylon Insert Jam Lock nuts are the same as Nylon Insert Lock nuts, only smaller in height.
- Flange nuts are not as commonly used as other but they do have their uses. The base of a flange nut it typically ribbed, so it grabs the surface. This will also damage the surface if a lot of torque is applied.
Next up is Thread Pitch.
The thread type of a bolt is defined using the values of Root, Crest, Helix and Pitch. The only value you have to worry about is Pitch as all the other values are also defined by the Pitch.
The thread of a screw is typically defined by TPI for standard bolts and TP for metric bolts.
TPI stands for Threads Per Inch. This is simply a count of the number of threads per inch measured along the length of a fastener, this is only used for American Standard bolts.
A standard bolt example is a #10-32x1-1/4. To break that down you have a #10 bolt that has 32 TPI (threads per inch) and is 1 & 1/4 inch long.
There is an american standard thread pitch table that will tell you the standard pitch available for a specific size bolt, here is a copy.
TP stands for Thread Pitch. Metric fasteners are specified with a thread pitch instead of a thread count. The thread pitch is the distance between threads expressed in millimeters (measured along the length of the fastener).
A metric bolt example is M4-70x10. To break that down you have an M4 bolt that has 70 TP (thread pitch) and is 10mm long.
There is a metric thread pitch table that will tell you the standard pitch available for a specific diameter bolt, here is a copy.
You can buy thread gauges pretty cheap, I’d recommend everyone have one in their tool kit. You can find a printable thread gauge here.
The dimensions of a bolt can be expressed in metric or imperial units. Diameter is the width of the screw shank. This should not include the bolt head. Length is the measurement of the bolt from the edge of the chamfer to the undercut of the head, this measurement should not include the head.
Lets finally discuss Bolt Material. Steel bolts are produced using carbon iron, uncoated steel is vulnerable to corrosion. Hardened steel bolts are stronger than steel bolts, but more brittle. They are made of steel treated using tempering and quenching methods. Stainless steel bolts are chemical and corrosion resistant with an appealing finish, but they cannot be hardened like carbon steel. Titanium bolts are hard, strong, light, and corrosion resistant. When alloyed with other metals, it increases strength and durability.
The construction material of a bolt is typically expressed through it’s Grade or Class. Here’s a chart that defines the material to grade/class relationship.
The majority of bolts are either hardened steel or stainless steel. Most hardened steel bolts can be had with a zinc coating (black) that makes them resistant to most environmental conditions and are typically cheaper than stainless steel bolts.
Finally, let’s spend a minute on Shoulder Bolts. Shoulder bolts are typically only used for axles (Surf Rodz) or Idler Pulleys. Typically Shoulder Bolt sizes are defined well, diameter x length x thread type & pitch and material. A 10x90xM81.25 Shoulder Bolt is 10mm Diameter x 90mm Length x M8 threads & 1.25 TP and is made of Alloy steel that has been quenched and tempered (AKA Class 12.9).
The SR Shoulder Bolts are pretty expensive for what they are, so here are some links to get them cheaper.
10x90xM81.25 Shoulder Bol [01], [02]. [03]
Most of the info and graphics in this post are from boltdepot.com. They are a great resource for information about screws, bolts and nuts. They host a printable tool sheet of fastener info, you can get it here.
