Rack Screws

Whether you are designing a network racking rig or making changes to your existing parts, it is easy to lose or misplace the cage nuts and rack screws.

Rack-mount screws are used in the racking system, usually to mount electronics or to the system’s vertical members.

Depending on where you are based, it can be different (the imperial rack rail, which uses M5 screws, is mostly used for U.S .- built racks, while in Europe you will most often see rack strips or full hole rack rails using M6 screws) and vary from manufacturer to fabricator.

One odd thing about the racks is, they don’t have a regular form of thread. Many rack rails on the market today actually have square tapped holes which require mounting with cage nuts.

What is a rack screw?

Rack screws are to fasten devices to a 19′′ rack’s vertical uprights. It doesn’t have a standard type of thread. 

What is the size of rack screw?

The three most common sizes and types of rack mount screws found in rack-mounted equipment are:

• 10 – 32 Threads

Historically, 10-32 threads are of the original form of server rack screws. The word 10-32 comes from Specifications issued by ANSI B1.1-1974 for Standardized and American Screw Threads for Bolts, Nuts, and Machine Screws.

• 12 – 24 Threads

The most commonly used in pre-threaded racks is the 12-24 thread size. The fasteners are slightly bigger than those on 10-32, and the threads are more closely aligned.

The word 12-24 also originates from the traditional Unified and American Screw Threads for Bolts, Nuts, and Machine Screws.

The number “12” has no numerical sense and used as a scale designator. “24” means 24 threads per inch. By measuring the diameter with a ruler at slightly less than 7/32 inches (5.6 mm), you can classify a 12-24 screw.

• M6 Threads

M6 threads consist of 6 mm metric screws. The main screw on the metric rack is called M6 x 1.

The ‘M’ stands for the metric. The ‘6’ is the outer diameter expressed in millimeters and the ‘1’ is the distance, often in millimeters, between the neighboring threads.

Metric threads are used in the USA and are widely used by HP and other multinational organizations in products.

You can classify an M6 screw by using a ruler to calculate the diameter. It’ll be 6 cm, or just over 7/32 inches (0.228′′).

What is the material of a rack screw?

• High-grade carbon steel construction
• Corrosion and rust-resistant black zinc chromate plating
• Pre-installed nylon washers

What are rack screws used for?

As mentioned above, rack screws are designed for mounting equipment to a 19  “vertical rack.

When it comes to racking equipment, most racks use 12-24 threads, Dell equipment uses 10-32 threads, audio racks and HP equipment uses M6 metric threads.

Size and Capacity in server racks – – – What is the difference?

The difference between a rack and a cabinet is one of the apparent distinctions between the server storage solutions.

Fundamentally, the variations are very slight, except that racks are relatively open, and cabinets are closed.

Instead of concentrating on the difference between racks and cabinets, businesses should stress size and capacity, as these aspects are among the most essential when selecting the right server rack.

The study clarified that when it comes to size, the racks are labeled in units marked with a U. Every “U” stands for 1.75′′. So, a 42U rack is around 73.5′′ high.

The height of a rack determines more than how much equipment it can carry in. It also provides a guideline for how much power can be transferred to the device in the room.

There are several racks on the market, but the most common type you see in data centers is the 42U-high 600mm-wide rack, which is between 1,000 and 1,100 mm deep everywhere. These all support standard 19 “IT products with mounting.

One typical rack you can find in a data center is a 36U rack, but the trend shifts to 42U. While the most common in the sector might be a 19′′ rack with a height of 42U, the report said other companies would install more massive server racks when they need to store equipment at higher densities.

Additionally, shorter racks support businesses that need more space between the server rack and the ceiling.

Rack Screw Holes

While operating with server racks, you need to be in a position to protect your computers. To do so, you’ll need to locate the screws or fasteners that match inside your rack’s holes.

When it comes to rack screw holes, there is no single set method, so it is essential to understand the different options when using them and other relevant details about this subject.

• Threaded Holes – Threaded holes are widespread, and they come in various sizes. A threaded hole allows a screw to fit in naturally and safely as they more quickly direct the screw in.

For 19′′ rack mount holes, the original design was a threaded hole. In a threaded hole rack, the rack uprights are thicker than unthreaded frames to ensure that the threads do not strip out.

Threaded racks fit well for audio equipment and no-rail cases. Most shelves carry threaded racks. Many modern fabricators of OEM servers have limited success in mounting their rails in threaded racks.

• Round Unthreaded Holes – IBM first introduced round unthreaded holes into the server racks market, but they have gained some popularity ever since. You will find several different Dell, HP and IBM OEM rails and other equipment that suit the unthreaded round holes.

Due to the universal square rack holes this type of rack hole has fallen out of favor in recent years. Although mainly found in older racks now, there are still some places where hardware for this kind of hole is available.

• Universal Square Rack Holes –  Square rack holes are presently the most common on new server racks. These have 3/8 “by 3/8″ square holes and are usually on steel uprights that can be anywhere from the thickness of .085 ” to .11″ which makes them sturdy enough to withstand almost any equipment.

This type of hole has made the creation of ‘fast rails’ much easier for fabricators. So rails reduce the upgrade time, and it helps to prevent failures. Another good thing about square rack holes is that they can be quickly and cheaply converted to a threaded hole using a cage nut, which will snap into the square hole.

Some examples of hardware that uses square rack holes:

• TechEdge 2 Post Racks
• Rail Kits
• Open Frame Server Racks
• Server Cabinet Enclosures

How do you mount a rack on a screw?

Here is a short guide of how to mount a rack on a screw:

Tapped Holes and Screws

All rack mounting holes have been tapped to acquire a specific form of rack threaded screw.

The problem with tapped holes and screws is that a thread can often break, or a screw in the mounting hole may attach and break off.  It will make the hole in the mount unusable.

There are other mounting alternatives for the server racks and enclosures where adjustment is the standard.

• Tools Needed

For installation, we suggest an electric screwdriver or drill with the right Philips, square or star bit (only if it has an adjustable clutch setting).

Use enough torque only at slow speed to securely hold the hardware to the rack. Too much speed and can permanently damage the device or the tapped holes.

Round Holes and Cage Nuts

Cage nuts and clip nuts are used to keep rack-mount screws in place. A cage nut consists of a steel spring cage built to lock onto the open mounting hole. The steel cage has a captive nut inside.

The nut may be removed and replaced with a new one if a screw is stripped or broken. That means that mounting the hole itself remains intact and functional.

Round holes and cage nuts were so popular that Dell specially made a rail for them. But, the Square Hole is the most common in unthreaded rack mount holes.

• Tools Needed

Again, we suggest an electric screwdriver or drill with the right Philips, square, or star bit (only if it has an adjustable clutch setting).

Too much torque or speed can still be a concern – but you will only end up removing the cage nut and screw (which can be removed easily with one of our removal devices for cage nut).

Square Holes, Screw-less Mounting and Cage Nuts

Square holes are the most popular in rack construction today. They require mounting without screw, without tools.

The rack-mount equipment with square holes can be hooked down to the lip of the square hole. This process makes swapping out hardware simple-so square hole server racks are perfect for environments where there is a lot of change.

Equipment not designed for square hole racks can still be used easily by using cage nuts that fit into square hole racks.

• Tools Needed

None of that! Unless your material is built for a square hole rack. You would then need to use the process of installing the round hole rack.

Cage Nuts and Washer

What is a cage nut?

 A Cage Nut is used for a rack that has square mounting holes. If you need to install a product into your frame that needs a threaded hole, you will use a cage nut. A cage nut is a square nut that has wrapped threaded holes in a piece of spring steel shaped like a cage.

The size you’d need would depend on what the product you’re assembling needs. To go with the cage nut, I still recommend buying the corresponding screw because it also makes installation simpler if the wrong size cage nut is selected.

Cage nuts can rip your fingers with your bare hands, trying to mount or uninstall them. Consider using a Tool for Cage Nut.

Washers

They usually consist of a flat, circular or disc-shaped metal piece with a hole in the center, washers often used in combination with threaded fasteners.

A washer can be inserted through the end until a threaded fastener, like a screw, is pushed into a surface.

When do you need lock washers? Lock washers are required when the assembly of the fastener is subject to vibration or is considered an issue wherever the backoff is.

Purpose of Washers:

• Load distribution
• Spacing
• Liquid protection
• Vibration absorption

What’s the right rack screw spacing?

The hole spacing on the mounting flange for regular 19′′ racks is lined out into groups of three holes. This group of three holes is known as a Rack Unit (RU), or sometimes called a U. 1U occupies a vertical area of 1.75′′ (44.45 mm).

The width of the three-hole group is determined from center hole to center hole and does not differ whether the server rack has square or round mounting holes.

If the installer fails to pay careful attention to where the slide rail is being assembled, this irregular hole spacing can trigger installation issues.

What is the usual problem with hole and rack screw spacing?

The size of the three-hole party is determined from center hole to center hole and does not vary whether the server rack has square or round mounting holes.

Unless the installer fails to pay careful attention to where the slide rail is being mounted, this irregular hole spacing can cause installation problems.

The most common issue is that the hooks or holes for the slide rail assembly do not fit with the holes in the server rack.

How to install rack screw?

1. Locate the holes in the rail you use to mount the equipment.

2. Obtain a nut from a cage and insert the nut’s lower lip into the square rail opening

3. Push the tip of the cage nut attachment instrument through the rail hole and grab the cage nut’s top lip.

4. Pull the cage nut through the hole using the attachment tool, until the top lip snaps into place.

What does #10 screw mean?

The “10” signifies the screw size and the “32” represents 32 threads per inch. It is a trendy type of screw and is available in different driver types.

Through measuring the diameter with a ruler to precisely 3/16′′ (0.190′′), you may classify a 10-32 screw.

Usually, 10-24 tells us about the screw’s scale and also its pitch diameter.  Those numbers provide us with the screw concept.

What is M5 rack screws?

The diameter and spacing of threads define metric threads. For example, the most common bolt size used on bicycles is 5 x .8, also known as “M5.”

That size is used for mounts for water bottles, cable anchor bolts, fender/rack eyelets, shifter mounts, etc. The “.8” indicates a gap of .8 mm separates the threads.

There is also the hardware of 5 mm diameter, of various thread pitches. The shorthand designation “M” signifies the standard coarse thread pitch (.8 mm in the case of “M5”).

Is M5 and 10-32 the same?  

The difference in pitch is not essential (.0315 “for 10-32 for the M5 vs. 0.03125”).

The M5 is a little larger in diameter than the 10-32. So, the modern M5 handle suits virtually any ear. The only exception to that will be the O.D. The handle is for the head ‘landing area’ (e.g., some Gillette News).

A 10-32 handle is not a sure thing on an M5 eye. It can suit, or not. When both the handle and the head are in a minimum state of material (a most massive hole, smallest screw), then you’re good to go. When both are in optimum material condition, it is not going to match.

What is M6 screw dimensions?

The threads have an outside diameter of 6 mm. Indeed the regular metric rack screw is an M6 x 1 mm.

Difference between 10-32 and 12-24 rack screws:

In pre-threaded racks, 12-24 is more popular now than 10-32. The 12-24 fasteners are slightly more significant than the 10-32 fasteners and have thread runners.

Its dimensions are the main difference between 10-32 and 12-24 threads. 10-32 screws have a diameter of 3/16′′ (4.8 mm), where the diameter of the screws as 12-24 is 7/32′′ (5.6 mm). M6 threads have a diameter of 6 mm, but just .4 mm more full than 12-24 screws.

When it comes to racking equipment, most racks use 12-24 threads; For example, Dell equipment uses 10-32 threads, audio frames, and HP equipment uses M6 metric threads.

Cage Nut tool

This stainless steel tool comes with a hard plastic covering on the back which includes a fast and easy reference guide to space size “U.” It also features 3 holes (10-32, 12-24 and M6) that are sized and labeled to make it easy for you to check which screws you own.

Putting up a cage nut with the attachment device is a snap — place the cage nut in the opening, hooking one of the tabs of the cage nut into the bar.

Stick the skinny end of the tool along the opposite edge through the hole, with the hook facing in. Using the hook to take the inside edge of the spring film and pull as shown above.