Thread Pitch Vs. Threads Per Inch (TPI)

Thread Pitch Vs. Threads Per Inch

Thread Per Inch (TPI)

diagram showing thread pitch

Threads per inch, commonly abbreviated as TPI, is a term frequently used when talking about fasteners.

TPI is a term used to help identify how many threads are in an inch. To determine treads per inch an inch of the bolt is measured and then the peaks on the fastener are counted. In the picture, you can see there are 5 peaks in the inch measurement. This means the TPI of this fastener will be 5. When looking at an example bolt measurement:

1/4″-20 x 2″

The 1/4″ refers to the bolt diameter (in inches), the -20 refers to the threads per inch meaning that there are 20 threads per inch on this bolt, and the 2″ refers to the length (also in inches).

Thread Pitch

Thread pitch is the term used to calculate the difference between two threads. For metric fasteners, the thread pitch is used in place of TPI. The distance is also measured in millimeters.

To measure thread pitch, use a caliper and measure from the peak of one thread to the next.

M2 x .4 x 5M

The M2 refers to the diameter of the bolt (in millimeters), the .4 refers to the thread pitch in millimeters meaning that there are .4 millimeters between each thread peak and the 5M refers to the length of the bolt it millimeters.

Why It Matters

Thread Pitch and Threads Per Inch are used to measure the threading of a bolt or nut to ensure that they will couple together properly. If the threading of a bolt and nut are different they will either seize or strip the threading resulting in an unusable connection.

A Word About Fine And Coarse Threading

Fine thread fasteners have a tighter helical structure and are usually less pronounced. A coarse thread fastener has larger deeper and more forgiving threads (meaning if the threading gets lightly damaged they may still work). Most standard fasteners and metric fasteners have a fine and a coarse thread version. You can identify each of them by using the TPI or Thread Pitch.

For US Fasteners, you might see 1/4″-20 and 1/4″-28. To determine which of these is coarse thread and which is fine, simply take the TPI number (the 20 and the 28) and compare. Remember a coarse thread means the threads are bigger so less will be able to fit within an inch so the 20 means the fastener is coarse thread and the 28 means the fastener is a fine thread.

*The TPI and Thread Pitch will change based on the diameter of the fastener so you will not always see 20 and 28.

For metric fasteners, you will see a M8 x 1.25 or an M8 x 1. For thread pitch, the distance between two points is the second number meaning the higher the number the fewer threads there are. This means the M8 x 1.25 is the coarse threading and the M8 x 1 is the fine thread.

If you have a problem identifying thread type and size, please use our Thread Identification Charts.

For more information about fasteners check out Fasteners 101.

For information on Thread Pitch & Threads Per Inch consider checking out our video on the subject below.

Black Oxide Coating: What Is Black Oxide?

SHOP BLACK OXIDE FASTENERS

Black Oxide Coating: What Is Black Oxide?

Black Oxide, sometimes called blackening, is the act of converting the top layer of a ferrous material with a chemical treatment. Treating fasteners with a black oxide coating not only adds a nice clean black look but can also add a mild layer of corrosion and abrasion resistance. To achieve the maximum in corrosion resistance, black oxide can either be waxed or oiled to add an extra layer of protection. The wax coating may dull the color of the treatment but provides the best resistance. The black oxide treatment is also referred to as gun bluing.

When fasteners are dipped into the black oxide bath materials (warm and hot processes) the harsh chemical components convert the top layer into magnetite. Black Oxide Stainless Steel Nuts Bolts and Washers are the most common form of black oxide fastener available. Prized both for the corrosion resistance of stainless steel with the added benefits of the black oxide treatment.

Materials That Can Get The Black Oxide Treatment

Stainless Steel
Copper
Copper Based Alloys
Zinc
Powdered Metals
Silver Solder

The Black Oxide Processes

Blackening can be achieved in a number of different ways. There are three main ways to do this. If you are interested in the specifics of each type check out this article from Wikipedia.

Hot Bath

The process of treating the fasteners in different chemicals in order to convert the surface material into magnetite. The process is completed by dipping the fasteners into different tanks and occasionally placed in water. Once the process of dipping is completed the top layer of the fastener is porous and a layer of oil is applied. The oil seeps into the material adding that extra corrosion resistance to rust. This process creates a black oxide bath that complies with MIL-DTL-13924, AMS 2485, ASTM D769 and ISO 11408 standards.

Cold Coating

The cold process applies a compound (copper selenium) onto the fasteners at room temperature. This process is more convenient for working in house as it does not require many chemicals at heated temperatures to apply. Once applied it is considered weaker than the other forms of oxidization until a layer of oil or wax is applied to the surface.

Mid-Temperature Bath

Like the hot bath treatment method but does not produce the same toxic fumes of the hot bath and the surface is converted to magnetite at a much lower temperature. This method can also meet the same military standards that the hot bath version produces.

Benefits Of Black Oxide Fasteners

Does not significantly change the dimensions of the fasteners as hot dip galvanizing does.
A cheaper alternative to other methods of corrosion resistance such as electroplating.
An appealing look when a bright shine is not desired.
The process can normally be done in large quantities which makes it faster and cheaper for smaller sizes.
Reduces the risk of galling by adding an oil finish
Decorative finish
Adds a layer of mild corrosion and abrasion resistance
Paint sticks well to the black coating if painting is required

Will Black Oxide Bolts Rust

Black Oxide adds a mild layer of corrosion and abrasion resistance to fasteners. Like any material, black oxide treated fasteners can rust in the right environments. It will depend on if the fastener is damaged or marred, the type of metal with the black oxide treatment and environmental conditions.

Disadvantages Of Black Oxide

Black oxide is not nearly as corrosion resistant as some of the other options available to improve corrosion resistance.

The black oxide finish can be easily rubbed off. To prevent this, put some painters tape over the tip of your bit to create a tighter fit and prevent scratching in the event of a slip out of the drive.

The Black residue from the fasteners may come off of them so for certain applications it is recommended that they are wiped down before use. This extra step can be labor-some if many fasteners are needed.

Black oxide fasteners are largely used in the automotive industry due to their sleek black look. This look can deteriorate very quickly though in hot environments. Often, after a black oxide coat is applied to a fastener, they are placed in an oil bath for an extra layer of protection. The oil residue that stays on the fasteners will begin to turn brown when in high heat environments. So many users find they bolts look like they rust prematurely. It is not recommended to place black oxide bolts on or near engines.

SHOP BLACK OXIDE FASTENERS

Custom Coating For Fasteners

Our company offers custom black oxide orders VIA phone orders. Can’t Find what you need in black oxide? Give us a call at 866-573-445 for pricing and availability!

Custom Fasteners and Hardware

How To Avoid Breaking Spanner Bits

SHOP SPANNER BITS

Avoid Breaking Spanner Bits

Broken Spanner Bit

The spanner drive style is still an uncommon drive style for most people to just have lying around.

This uncommon bit makes screws more resistant to tampering and removal without the proper bit. Due to this, a spanner bit is often referred to as a “tamper-proof” or “security” bit.

The Problem With Spanner Bits

As great as spanner “snake eye” bits are for adding security to an assembly, they also have some downfalls. Spanner bits are made to fit a very specific drive size. If they are used with the wrong size it becomes increasingly likely that the bit will break.

Spanner bits are also more prone to snapping than any other bit type. The spanner bit has two prongs that are inserted into two holes in the head of the screw. Pressure is then directly applied to only those two prongs (across a very small area) which causes the screw to turn. Other bits can have as many as six sides pushing on the head making it less likely that they will break by spreading the load across multiple points of contact.

Spanner bits are commonly avoided for this reason but there are actually a few easy steps you can take to avoid most of the common reasons spanners break.

Steps To Avoid Breaking Spanner Bits

Always Pre-Drill Into Hardwood

Hardwood can be particularly difficult for screws to cut into. We recommend pre-drilling a pilot hole even when the screw has a self-drilling tip. Pre-drilling a hole removes much of the wood that would be in the way and allows a screw to more easily install.

Avoid Coming To A Hard Stop

Drilling into knots or using a screw that is too long where it can hit metal on the back of the installation surface can cause the screw to seize in place. This sudden seizure will place all of the pressure upon the bit prongs and more than likely cause them to snap.

Avoid Over-Installation (Over-Torquing) Of The Screw

When installing the screw, make sure to stop once the head reaches the installation material. Attempting to screw the fastener in further will increase the amount of torque required to turn the screw dramatically.

Watch As Bob demonstrates this with one of our own spanner bits.

*No spanner bit regardless of quality will stay in tact if you do not take care when installing spanner drive screws. It’s the nature of the bit design.

DIY Magnetic Sockets – Save Time – Don’t Drop Your Bolts!

SHOP SOCKET EXTENTIONS

DIY Magnetic Sockets

Socket Extension With Magnet Attached

Are you trying to install a fastener in a hard to reach area? Constantly dropping bolts when you go to tighten them?

We’ve all played the balancing game of trying to keep a bolt in a socket while we turn it over only to have it fall out of the socket and into the depths of you engine bay never to be seen again. We sat down (in frustration) with our fastener expert Bob and he gave us a quick tip on how to avoid this issue in most situations.

What You’ll Need

Crazy Glue
A Small Round Magnet
Socket Wrench Extension

How It Works

Take the socket wrench extension and place the magnet on top. Make sure the magnet, when seated in the middle of the extension allows the socket to still slide over the top and connect. At this point you have one of two options:

Use this as a temporary solution so you can remove the magnet once completed
Remove the magnet, coat the bottom in crazy glue and reapply it to the extension, creating a permanent solution.

Using It

Now that your magnet is installed, all you need to do is choose the right socket for your bolt and place it on the extension. Slide the bolt into the socket and the magnet will grab the bolt. On some metals such as plain steel, the magnet should grip the bolt firmly, On stainless steels (which are all partially magnetic) there should be a light grip, but unfortunately on non-magnetic materials such as aluminum there still isn’t grip. These bolts are still going to be a pain for all of us.

Aside from non-magnetic fasteners, the only other time this fix will not work is when the extension is too long. Often, there is little space where the bolt needs to be installed so adding the extension to the wrench will make this task unlikely if not impossible to complete.

Conclusion

Overall, this easy and cheap trick can save us all a lot of time, searching for bolts that never hit the floor but seemingly vanish from existence and the frustration of dropping a bolt repeatedly. If you have a spare socket extension or a few bucks lying around, give this a try and let us know how it works out for you.

How To Replace A Utility Box Cutter Knife Blade

SHOP UTILITY KNIVES

How To Replace A Utility Box Cutter Knife Blade

The box cutter, or utility knife, is an excellent tool found in almost every warehouse. Designed with a small blade, these knives have the ability to quickly cut cardboard boxes open, remove packing tape and other wrappings used in freight transit. Due to the abuse box cutters take, they are often made from very hard plastic or metal.

Many warehouse employees view utility knives as throwaway items. As soon as the blades wear out warehouse workers will typically begin looking for a new one. Fortunately, you’re company does not need to waste money repeatedly buying new box cutters every week. A simple remedy is just to replace the blade. And the best part? They normally come with extras!

Opening The Utility Knife

The first step when replacing a box cutter blade is to figure out how it opens. In our example, we only need to use a Phillips head screwdriver and remove one screw from the side. After removing the screw you can simply pop the top off which splits the knife in half.

Identifying Components

There are really only five components to our utility knife. The handle, the screw, the blade, the blade housing and the pack of replacement blades. Once the blade has been opened, we can remove the blade housing and blade from the knife.

Identifying the box cutter components

Make sure when you reach this point you pay attention to how the knife sits in the housing. After noting this you can remove the knife from the housing and dispose of it safely.

Replacing Blades

The replacement blades are normally wrapped in a little pack. They often come in sets of between three and five. You will want to carefully remove these blades from the knife Finding the extra blades in the utility knife handle so you do not cut yourself. Then unwrap the blades and remove one from the package. After you have a new one out, place the other blades back into the handle.

Now take the new blade and seat it into the housing the same way the old one came out. The blades in this knife have a two notch system which needs to get placed correctly back into the housing. This creates a nice firm hold on the blade.

Putting The Box Cutter Back Together

At this point, we will want to start reassembling the box cutter. Place the blade and housing back into the handle, ensure that the extra blades are seated properly and then place the top of the handle back onto the bottom. Then fasten the screw back into place and your utility knife is as good as new.

Checking for any design in the blade of a box cutter to ensure it is seated properly.

*When fastening the screw back into place you want to make sure to snug the screw but not over-tighten it. If you over-tighten the screw it will compress the handle and seize up the blades movement in the handle. To mitigate this, tighten and then check by opening and closing the box cutter a few times to make sure it is at a comfortable resistance to opening and closing.

Our Thoughts

We are using a standard metal box cutter in our example but many blades work in the same or a very similar fashion. Utilizing these blades will end up saving your company a fortune in the long run. Make sure you educate employees on the extra blades (if available) or have an employee who can change them readily available to change blades out for the other employees. The type of box cutter we used, after spending about five minutes on it the first time, we were able to change a blade in about two minutes. Making it significantly cheaper to have someone change the blades than to just buy more.

Replacing a Utility Knife & Box Cutter Blade

Utility/Box Cutter Blade Replacement Transcript

Scroll Down To Continue Reading

Bob: Welcome back to Albany County Fasteners – Fasteners 101. Today I want to show you how to properly change a blade in a utility knife. Lets get started.

So I have my utility knife here. This is just a standard utility knife. This is like a five dollar utility knife. You can get more expensive utility knives, unless you’re a contractor or or one of those guys that are using it professionally every day, this will do. This is a very simple unit.

Now I’m going to show you how to change the blade properly you need a number two Phillips and we get out of my case here. OK and i’m just going to unscrew this Phillips screw right here.

I’m gonna take that out. Remove the screw and then you just pop this top off. This whole mechanism comes out of the utility knife, like a casing, and then in the back, typically in the back of the utility knife itself, they give you a little package of additional blades. In this case they give you four extra ones.

So you take the blade out of there, you take the mechanism that it snaps into. So now, there are two holes. There’s only one you can get it into alright, so two slots they see those two slots you can only get it into one and that’s the only way will fit. It should fit snug in there, you shouldn’t get a blade that is sloppy and moves around and it should just fit perfectly as I’m showing you here.

Once you have that, you can just slide this, put it back in there, but the key to this is pushing this down so it will slide back and forth. Now when you put the top on, there’s a lot of people running into this problem. If they don’t put that in properly it won’t adjust for you and then this is like a hinge you just snap it in like that.

Before you put the screw, when you start screwing it, make sure that you have rotation; that it’s sliding back and forth for you. Put the screw back in, just snug the screw, don’t over tighten it, I just tighten it. I just tighten it till it stopped.

There you can see that it was free. A lot of times people over tighten this, put all their muscle into it and then in this case it’s not happening but in some utility knives it will not function properly.

There you go. Thanks for watching.

SHOP UTILITY KNIVES