rack screws??

  • Thread starter Thread starter dmbfan1981
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dmbfan1981

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is there anything fancy about rack screws?? Are they just simple 10-32 pan head screws?? Should you use nylon washers or metal? Any other tips or tricks for mounting rack gear that anyone wants to share?? :confused:
 
Nylon washers are there to protect the equipment from getting rack rash, or at least not as much as you would with a bare screw. I just buy bags of them from fullcompass, cause they come with nylon washers, and they are cheap. Maybe you could do better at home depot, I have never gone to go look.
 
I use nylon shoulder washers, on both the front and back of the faceplate of the gear being mounted. The shoulder lifts the gear off the screw and along with the washer between the faceplate and the rack rail, isolates the gear from the metal of the rack.
 
SonicAlbert said:
I use nylon shoulder washers, on both the front and back of the faceplate of the gear being mounted. The shoulder lifts the gear off the screw and along with the washer between the faceplate and the rack rail, isolates the gear from the metal of the rack.
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Is it important to keep the rack units isolated? I used to do it that way as well, but got lazy when I had to change some stuff around. Didn't really notice any difference.
 
thanks guys. I will check out full compass and home depot to see whats the cheapest.
 
My machinist friend says the Middle Atlantic screws are well made. I do know that some of the hardware store screws I've used on non-audio projects strip out and go fubar on me so... The real thing might be worth the price in this instance. Tell us what you find out.
 
pikingrin said:
Is it important to keep the rack units isolated? I used to do it that way as well, but got lazy when I had to change some stuff around. Didn't really notice any difference.
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There's actually two schools of thought on that... some will bond all of their rack gear to a common ground... others will isolate... either, in a perfect world, works (I prefer bonding the entire studio to one common earth ground).

Simply using plastic washers behind and in front of the rack ears doesn't ensure electrical isolation because the screw passes through the rack ear hole and can still make contact and complete an electrical circuit...

There is a company that sells thru-hole rack washers... though I can't for the life of me remember...
 
The shoulder washers in most cases lift the rack ears off the screw. But yes, the thru-hole rack washers would be better for that if isolation is what you are going for.

I do use screws made by Middle Atlantic, and they work great.
 
dmbfan1981 said:
is there anything fancy about rack screws?? Are they just simple 10-32 pan head screws?? Should you use nylon washers or metal? Any other tips or tricks for mounting rack gear that anyone wants to share?? :confused:
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They're actually not standard machine screws, no. Equipment racks are generally not pre-tapped (threaded) when you get them. The screws actually tap the holes the first time you screw them in. That's why they're so hard to screw in the first time. They're actually behaving like a die and cutting their own threads.

You can tell that they are tapping screws because they are shaped differently, with the tips tapering down to a much narrower size so that they center themselves before they catch. photo of a self-tapping screw This means that normal screws would just strip out.

Of course, you only need one bag of rack screws. After you've tapped all the holes, you can use any standard screws. Oh, yeah, and when you run them in the first time, you should periodically (maybe once every full turn or so) twist them in reverse a fraction of a turn to clean the grooves, or so I'm told.

Note: some racks probably come pre-tapped, in which case you can disregard this.
 
Every rack and rack rail I've ever bought has been pre-tapped. I've never once seen a rack that wasn't.

What kind of racks are you buying, who makes them?
 
It probably seems like they aren't because of that powder coat, or paint or whatever, is gumming up the threads. I just bought one of those cheap table top racks and it was like that, you could see all the paint falling out from getting the screws in the first time. They weren't self-tapping screws though...
 
And, FWIW, there are different standards in rack rails in the USA.

The more popular one is the pre-tapped for 10-32 screws. In telecommunications, there are ones pre-tapped for 12-24. There is a metric standard sized at M6.

Some racks use cage nuts and you see some using clip nuts. These racks are more popular for use on rack gear in the computer world than the audio world but I use one and love it.
 
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all VERY useful info. I just called GC and they have a pair of 6-space for 12.99. Two pairs of those should do me. I will look into screws and washer and try to make a good decision.
 
ozraves said:
And, FWIW, there are different standards in rack rails in the USA.

The more popular one is the pre-tapped for 10-32 screws. In telecommunications, there are ones pre-tapped for 12-24. There is a metric standard sized at M6.
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Interesting. The screws I bought might have been self tapping for a slightly larger size. They were from a computer store, presumably for telecomm racks. Regardless, the telecomm racks I've used definitely are not tapped, as even the non-painted ones are an absolute bitch to screw into the first time. :D
 
Like above, every rack or set of rack rails i've delt with is tapped. But they usually have thick paint or powercoat (usually the second), which can add alot of material. I would image that on a threaded hole, the powdercoat will make the hole close to 1mm smaller.
 
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