Rack-mounting screws for mounting equipment, shelves, and accessories onto IT racks
Rack-mounting screws are used to rack-mount equipment, shelves, and accessories onto 19-inch racks such as 4-post server and equipment racks, 2-post relay racks, wall-mount racks, Telco racks, etc.
Whether 2-post or 4-post, racks typically come with rails fitted with one of two types of mounting holes:
- Square holes in 'universal' rails, designed to house cage-nuts
- Threaded holes in pre-tapped rails
Universal Rails (with square holes)
Originating in Europe and initially brought to the United States by Compaq, racks fitted with 'universal' square holes are now commonly used in enclosed equipment racks as well in open 4-post and 2-post racks for mounting servers, network gear, telecommunication and other IT equipment.
The square hole requires a cage-nut be inserted into it to make it useable for mounting equipment.
A cage-nut consists of a steel cage which wraps around the nut, in which the nut is situated in a way that permanently holds the nut in place. A cage-nut also consists of two spring 'wings' that - once slightly squeezed - fit into a square hole in the rack's mounting rail and, when released, hold the nut in position behind the hole.
The nut is being held slightly loose with some wiggle room in the 'cage', allowing for minor adjustments in alignment, making it easier to have the screw find its way to engage the nut.
Mounting screws & cage-nut sets are available in two sizes:
• Metric M6. The M6 screw has a metric thread size of 6 millimeters, which is the typical thread size for European rack applications. The M6 screw is larger than both #10-32 and #12-24 screws.
• American #10-32. The "10" refers to the drill size for a tapped (threaded) hole. #10-32 screw type has 32 threads per inch, with an outside diameter of 0.19". #10-32 screw is smaller than a #12-24 screw.
Both versions are compatible with 'universal' square mounting holes commonly featured in IT racks.
When mounting servers and other heavy IT equipment onto 4-post equipment racks, the use of M6 screws & cage-nuts is preferable, since they are larger and stronger than #10-32.
Tapped Rails (with #10-32 or #12-24 holes)
Racks fitted with round mounting holes are common in relay racks, Telco racks, wall-mount racks, and communication-closets boxes and brackets. The mounting holes are typically pre-tapped (threaded).
Depending on the rack, these pre-tapped holes may be threaded to meet two standards:
• #10-32. The "10" refers to the drill size for a tapped (threaded) hole. #10-32 screw type has 32 threads per inch, with an outside diameter of 0.19". #10-32 screw is smaller than a #12-24 screw.
• #12-24. The "12" refers to the drill size for a tapped (threaded) hole. #12-24 screw type has 24 threads per inch, with an outside diameter of 0.2160". #12-24 screw is larger than a #10-32 screw; smaller than an M6 screw.
Since the holes are typically pre-tapped – 'standard' mounting screws typically work well with these rails. However, pre-tapped rails may have their holes slightly clogged with paint (or powder-coat), making it more difficult to use 'standard' mounting screws. Self-tapping screws typically overcome this hurdle for an easier installation.
Self-tapping screws must be used with racks that are fitted with mounting holes that are not pre-tapped.
Rackit's Mounting Screws and Hardware
Rackit's rack-mounting hardware is available in three (3) styles to accommodate most any IT rack:
- Mounting screws with cage-nuts for square 'universal' mounting holes
- Self-tapping mounting screws for #10-32 or #12-24 mounting holes
- 'Standard' mounting screws for pre-tapped #10-32 or #12-24 mounting holes
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