Like most folks, nearly all of my electronics and computer gear--well, the stuff on shelves anyway--was stacked on a shelf with the wires gently shoved behind everything. When anything failed--and something always did--it was nearly always the piece of equipment on the bottom of the shelf. This precipitated the usual round of trying to balance all the other equipment with one hand while unplugging and untangling the cables from the back with the other hand. And also invariably, I'd pull half the cables either out of the wrong component or out of the back of unit they were sitting in.
When I finally got to the point where I could have a [relatively] custom office, I decided that none of the computer equipment was going to suffer from that any more. Components were going to be only one deep on each shelf and i was going to manage the cables so that they were organized and I could get in and out of the cabinet with ease.
Which was easier said than done...
The shelf part was easy; I'd just make sure I had enough shelves and make sure they were installed with pullouts. The cable part was another matter; and in fact the pullout made the cable part more urgent. Just sitting components on shelves and allowing cables to dangle meant that I was probably going to crimp, crease, score, slice or otherwise screw up all of my cabling. I'd seen several cable management arms for rack-mounted equpment; however, they were both way too wide (for your typical 3/4" shelf) and way too expensive (for your typical cheap nerd: me). After lots of design experimentation I finally came up with the piece here.
Incidentally, this is my first attempt at an instructable (please be gentle with me :-). And I apologize in advance for the quality of the photos. I tried to take them one handed so that you can see me manipulating the pieces; however, I'm not particularly steady when I do that. All of those photos look like a cross between earthquake pictures and something from the movie Cloverfield (and have been--mercifully--left out).
Step 1: Get Set Up
The first thing to do is gather materials and take appropriate measurements. My control arm dimensions are based on two important measurements: the depth of the cabinet and the thickness of the shelf. I'll deal with the second one first.
My shelves were 3/4" particle board with a front trim edge for strength and to make a more attractive edge. So I'm using aluminum C channel that has an interior width of 3/4". Honestly, an exterior width of 3/4" would be better, but my local big-box home improvement store doesn't have that. And with a thickness of 1/16", it really isn't that far off (more on the thickness issue momentarily). I also used two pieces of aluminum 1/16" bar stock--3/8" and 1 1/2"--that I'll cut down for connectors.
The depth of the cabinet decided the length of the stock; my cabinet is 24" deep (actually, more like 23.5"). Therefore, each part of the arm needs to be close to 12" long so that when the shelf is fully extended, the arm isn't overextended (check out the diagram for a little more clarity). Given the number of these I was planning on building (3 shelves worth), I needed 6' of C channel. For the bar stock, I only needed about 1' of the 3/8" stock and about 2' of the 2" stock.
Regarding the connections, the unit itself is connected using 1/8" pop rivets--8 of them per arm. The arm is connected to the pull out shelf using two #8 machine screws and nuts (1 1/4" length). The other end of the arm is connected to the back wall by 4 #6 5/8" wood screws; however, you can use whatever length is appropriate given the wall you're attaching to.
Regarding tools, you'll need something to cut down and shape parts of the aluminum stock. I used a right-hand and left-hand set of tin snips and a bench grinder, but you can do all of it with only a bench grinder. You'll also need a drill with an 1/8" drill bit as well as a hacksaw (or some other tool to cut the aluminum stock) and a center punch and a hammer. And the pop rivet gun, of course.
What about the 1/16" issue? Well, thicker (1/8") would be better but it would make fabrication more difficult. The necessary strength is really dependent upon how much weight the arm has to bear and how often you plan on moving the arm. So if you need a really strong arm, thicker stock would be better ... or using a different metal (like steel). In my case, neither was an option (couldn't get the aluminum thicker and the steel was just too expensive). So far, these have held up well.
OK, let's get started.