🔩 Fasteners - What they are, what's in your kit

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.

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.

  1. 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.
  2. 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.
  3. Nylon Insert Jam Lock nuts are the same as Nylon Insert Lock nuts, only smaller in height.
  4. 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.


Don’t forget the dangers of using stainless fasteners: Stainless fasteners, unless you get some really super aerospace-grade ones (A286 for example), are much softer/weaker than regular or high-strength (E.G. Class 10.9 or 12.9) steel/alloy fasteners, and are more prone to stripping out. Sure they look pretty and won’t rust, but if you can’t get them out again, you’ve got problems. Typical A-2 or similar stainless is weaker than even a class 8.8 steel screw, which is why if you have to use stainless, I recommend a Torx drive rather than regular hex, because it’s far less likely to strip.


I had actually meant to include some info about stainless strengths but I couldn’t find the table that shows those values. Ill find it tonight or tomorrow and add it to the main post.

What about where to get them? I was gonna drop like $40 on assorted hardware from McMaster unless you have a better source (lots of variety)

It’s in your grades/strength classes graphic, at the bottom.

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Where to get them is entirely different topic. I buy standard locally for the most part, but most metric comes from either McMaster Carr, Amazon or AliExpress.


I have another that shows tensile & torsion strengths of stainless steel using the diameter to sort, just gotta find it.

I get most of my more generic fasteners from BoltDepot.com in the US. Specialty stuff from McMaster or Accu.Co.Uk, or anywhere else I can find it lol

Nicely done. @mmaner :+1:

BoltDepot, AceHardware (local usa/limited), Fastenal (local usa/limited), HomeDepot (local usa/limited)

Special bolts need to be bought online usually though. McMaster should typically have everything you would want.


Right, forgot about Fastenal.

Thank you sir, all good sources.

learnt this the hard way. i now only use high tensile socket cap bolts on my motor mounts as otherwise the mf Philips head in my stainless hardware strip’s out…

Yeah. Even hex head ones will strip pretty easily. Torx is OK, but then the lower tensile of the fastener itself comes into play, and it’s not too hard to accidentally twist the head right off the screw.

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precisely, i always thought stainless was stronger but ding dong i was wrong lol. I used a stainless m5 with a torx head and it was so damn soft

accu or boltbase in the UK. There are actually loads of specialty UK companies that stock a crazy array of fasteners but pricing can be really prohibitive.

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if you’re in Sydney aus, this is your place to be

I am suprised I haven’t seen a lot of builds using torx, after stripping 12 hex bolts holding my enclosure on I’ve replaced those bolts with torx and they work so much better than hex.


This is a great post very useful for the many people that don’t use variuse fasteners all day. It’s important to use the right terms because fastener slang can in reality mean multiple things and it is easy to confuse some one who is new

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thank you sir.

I would add the NordLock washers. They are anti vibration washers and work great on our application. Especially mounting the motor to the mount.