Rack newbie - cage nut hell

[SRussell]

Finally bit the bullet and bought a 24U rack; nice little APC unit. Guy selling also threw in a bag of cage nuts and screws. After mentally stepping on a few pieces of Lego bricks I realized that there are three different sizes of cage nut threads. Lucky me; I have a bag of evenly mixed sizes all the same coloration.

I am running all SuperMicro chassis, CyberPower UPS, and will likely stay on the SM bandwagon vs Dell or HP.

What size cage nuts threading should I standardize on: 10-32, 12-24 and M6? Is there a minimum screw length that should be used? I am not a fan of Phillips but that appears to be the dominant head. I have found Allen and Robertson headed screws but I am not sure if these heads would lead to over-tightening.

Lastly, do I need a washer? If so, does it matter if I use flat or lock washer? Is it better to use plastic or metal?

 

[pricklypunter]

Personally I would go with M6, as that's what I'm mostly familiar with, the other sizes often being used for telecom's equipment racks, rather than servers and network equipment. Have a look at your local hardware supplier though and see what is easy to obtain where you are and go with that. Just remember that if you run out of cage nuts later and have to add more, you will need to find the same type again or you'll end up with a mix of sizes in the rack, which, although workable, always becomes a pain in the backside at some point. As for length, most commonly I have used 12mm and 18mm (1/2" and 3/4"). You want at least a few threads sticking out beyond the back of the nut when all is tightened up. A little longer is fine, but never shorter. I would use thick plastic flat washers, they are not taking any weight, merely preventing marring of the surface finish of your equipment, but remember to add the thickness of them plus your nut, plus your rack ear plus a couple of thread pitches, to give you a minimum screw length, pick the next common size up. I would take the thickest rack ear and size off that for everything.

In saying all that, I have seen 2" machine screws holding up 1U Switches before, I guess that was all they had in the tool box that night

 

[SRussell]

In saying all that, I have seen 2" machine screws holding up 1U Switches before, I guess that was all they had in the tool box that night

There is a lot of truth in that statement. The people who built this house have slotted and Phillips screws in two different colors for the wall plates.

 

[Evan]

M5 is also common. Only thing to usually care is match the cage nuts to the screws.

 

[Blinky 42]

I stick with M6 but keep a small bag with M5 sets in my tool bag for the cases where the ears on a switch or whatever oddball shelf I am mounting won't take a m6 screw. I avoid the English sizes, only run into them when dealing with 2-post or crappy threaded hole racks.

Washers I was originally against back in the day, but after tearing down racks the washers when used make that much easier because it is less likely the screw is really bound in there and you can get it out clean - especially with front mounted equipment where most all the weight is on 2 of the 4 screws. Even more important when you use a powered screwdriver to rack equipment vs manual.

I have bought many of theses sets (25, 50 and 100 versions) Amazon.com: NavePoint M6 Cage Nuts and Screws for Rack Mount Server Shelves Cabinets Set of 100: Home Audio & Theater not the top of the line but decent for the price and black. Screw made well and the phillips head works with your standard #2 just fine with a manual screwdriver or small electric when racking up a lot of equipment. The nut is easier to get in that some of the other cheap ones. There is also a Tripp-Lite branded set you can get from major retailers that is good quality but generally more expensive.

 

[i386]

I stick with M6 but keep a small bag with M5 sets in my tool bag for the cases where the ears on a switch or whatever oddball shelf I am mounting won't take a m6 screw.

I think I had that problem with my mellanox or arista rail kit. I had m6 screws lying around but two mounting holes were threaded and required m5 screws...

 

[Patrick]

Someone just gave me some Chatsworth Clik-Nuts. Not something to recommend on this thread since they do not solve the size problem, but I have been converted.

 

[SRussell]

Someone just gave me some Chatsworth Clik-Nuts. Not something to recommend on this thread since they do not solve the size problem, but I have been converted.

These are pretty damn fantastic.

 

[Blinky 42]

Someone just gave me some Chatsworth Clik-Nuts. Not something to recommend on this thread since they do not solve the size problem, but I have been converted.

Ahh that is what those are called - I have seen them a few times here and there and always wondered what they are. Wouldn't need my stubby flat-head to pry the damn nuts in and out all the time Going order some and experiment.

 

[Serverking]

damn nuts

These nuts are making me thirsty!!

 

[Cixelyn]

At least in the US, it's much more difficult to get M6 in the average hardware store vs. 10-32 or 12-24. On one hand, metric is better down with imperial, but on the other hand the convenience of being able to get 10-32 on a moment's notice from the mom-and-pop hardware store down the street is useful flexibility.

Also we started using Clik-Nuts in our lab rack from a vendor sample, and we're also full converts. We want to buy more but now we're stuck with the same question -- do we all-in on M6? or 10-32 clik-nuts? At least I know now not to buy the Black Zinc ones -- finding black cagenuts in a black rack is such a pain.

 

[itronin]

Someone just gave me some Chatsworth Clik-Nuts. Not something to recommend on this thread since they do not solve the size problem, but I have been converted.

I received my free samples on Friday - they really are awesome!