There is no single set standard when it comes to the rack holes to secure your devices to the rack. Therefore, it is important to understand the different options, their pros and cons, and when they should be used.

Square Rack Holes

Square rack holes are the most common rack holes in the market today. The standard square sizes are 3/8” by 3/8” varying from 1.5 mm to 3 mm thick. The standard cage nuts work with the standard square rack holes. However, different cage nuts have different threads with most common variations being M5, M6, 10-32, and 12-24.

10-32 and M5 are similar in size. For 10-32, the “10” refers to the size of the screw (Dia. 0.19”) and the “32” denotes 32 threads per inch. As a metric coarse standard thread, the M5 measures roughly 5mm at the outside diameter of the thread with a pitch per 0.8mm. Be sure to check the threads before accidentally cross threading them.

12-24 and M6 are also similar in size. For 12-24, the “12” refers to the size of the screw (Dia. 0.216”) and the “24” denotes 24 threads per inch. As a metric coarse standard thread, the M6 measures roughly 6mm at the outside diameter of the thread with a pitch per 1mm. These screws generally offer better load capacity without much increase in cost compared to 10-32 and M5 screws. Be sure to check the threads before accidentally cross threading them.

Squared hole racks are typically cheaper than threaded hole racks. They offer the flexibility to replace the threads if damaged by replacing the cage nuts. However, depending on the size and time constraints of the project, it may be time and energy consuming to install and reinstall when adjustments are needed.

Some of the server equipment uses rack rails that can only be installed on square rack holes. Check your equipment mounting specifications before making the decision.

Threaded Holes

Threaded rack holes come with different thread varieties including the four types of threaded mentioned above (10-32, 12-24, M5, M6). Most shelves and audio equipment do not need rails. Without the need to install cage nuts, using a threaded hole rail can be a significant time saver.

The worst thing that can happen to a threaded rail is when one of the threads stripped. The stripped thread means the rack unit is no longer mountable and skipping over the rack unit decreases the overall rack capacity. The ways to fix the situation include to replacing the rail or adding a hex nut behind the rail. 12-24 or M6 threads are less prone to thread stripping due to their higher strength capacity. Therefore, NavePoint recommends going with 12-24 in the US as the default thread for threaded hole racks.

NavePoint offers 12-24 threaded interface on 2-posts racks, 4-posts racks, vertical rack rails, and more.

Furthermore, some of NavePoint’s product offers both interfaces at once, so you can start off with threaded holes and move on to cage nuts when the need arises.

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