What are 'standard' depths for for post EIA racks?
Various sites advertise their product specs, but they don't always agree. Belden has a series of depths available (24, 28, 32, 36 inch depths):
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But I pulled an HP rack-mount terminal out of my scrap pile and measured the (not adjustable) depth between front and back mounting flanges at 29.75". This would suggest a 30" rack (1/4" off since my rack mounts to the inside of the rack rails.
I'm building up a rack (home brewed) to fit in an oddball location. I know that some side rails are adjustable. But some (see above example) are not.
What's the true story on standard front to back depths?
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Paul Hovnanian mailto:Paul@Hovnanian.com
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Telemark: If it was easy, they'd call it snowboarding.
Well, apparently, you can get them in 24, 28, 20, 32, or 36 in. depths, and probably more. I've seen rackmount stuff, and very seldom have I seen anything that depends on a specific rack depth. I _have_, however, seen horizontal rails from front to back where any depth of box can just sort of sit there, actually secured only by the panel.
To quote what's-his-name, Wot's yer real problem? ;-)
I don't think depth is a controlled standard.(?) I could be wrong about that, though.
Now, the hole spacing on the rack rails "IS" a standard, and there are (2) main flavors. One has the holes spaced in an alternating pattern to accept 1RU (1 rack unit) gear, and the other (mostly used in older communications relay frames - I think?) used evenly spaced holes. The two are not interchangable if you don't intend to leave blank spaces between equipment.
An RU is 1.75 inches tall. Standard racks are either 19 or 23 inches wide.
As to depth, one of the reasons I don't think this is a standard (or at least, not one that's followed very often), is that I've seen rack- mounted test equipment that have mounting ears in the center of the equipment sides. In other words, part of the equipment front sticks out significantly from the rack side rail.
As to hardware, most racks use 10-32, or 12-24 threads. I prefer pan-head philips, but lots of folks use slotted hardware or even hex heads.
FYI - Newton Instrument Company is another good resource for all things relay rack. Link:
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Also, Home of Metal Enclosures (or whatever they're called these days), has some unique wall-mount racks for tough situations. Link:
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Of course, all this stuff is pricey, and of little use if you've got stuff laying around. Still, a good resource for info, or if you need weird little hardware, etc... Good luck.
It depends on the application, AND the deepest component you have that needs to be racked and stacked, AND how much space needs to remain behind the component stack(s) after they get fitted.
We get racks with three sets of rails in them. Two get shelving for added heavy weight item support.
Those are the "seismic" racks. Others are 44U high (huge) and approach
4 foot depths.
ELMA, the Power supply and chassis maker, also makes rack cabinets (well, they bought the company that does).
There are no "evenly spaced" mount rails any more. Well, unless you specify one made custom.
ALL racks these days are drilled out at EIA 1U spacings. The even hole space rails will NOT accommodate modern gear, but the EIA rack rails usually WILL allow some of the older gear to be used.
With a rack already costing plural thousands of dollars, adding custom rail specs likely adds a third to the price of an off-the-shelf rack.
On the contrary, Newton stocks racks with several side rail hole spacings, including: (.... one of which, WECO, I've never even heard of.) But you're right - I don't see the hole spacing that I was thinking of, which IIRC was 1/2" uniform spacing down the entire frame. It's been YEARS since I've had to spec an open frame relay rack. I'm glad to see the world "went EIA". Non-standard rack rails were always a pain to deal with.
I'm building a rack for some audio/video equipment. I've got the panel widths, heights and rail dimensions pretty well documented.
But I'd like to pick a standard nominal depth (24" looks like it will do) and then fabricate the frame so that the front to back rails are at the proper depth for the nominal value.
I've seen some shelves and drawer supports that are continuously adjustable. These will not be a problem. However, some shelves are adjustable* in fixed increments (pre-drilled holes). So knowing the actual front to back dimension for a 24" depth (for example) will save me from having too shim and/or drill a bunch of stuff.
*Some are not adjustable. The one I found in my scrap pile is set to 29.75" deep. No adjustment possible. If I want to use this in my a/v rack I'd have to cut it down.
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Paul Hovnanian mailto:Paul@Hovnanian.com
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If the first attempt at making a drawing board had been a failure,
what would they go back to?
Well, then, look at whatever it is you're going to put into the racks, and pick the depth that fits the biggest piece, and make up the difference in the rest - I've seen them just leave the box dangle there, holding it only by the front panel. (when they install it, they let it lie on the box below it.)
You do realize that you can have multiple depths in a single rack? You can put two or more sets of rails in adjustable racks, as long as they don't interfere with each other. You can also turn them so yo can get within an inch of each other, if needed. The extra rails are nice places to secure bundles of cables, as well.
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It's easy to think outside the box, when you have a cutting torch.
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