First of all, I'd like to thank the original poster, gregzo, for his write up which inspired me to put together my own mount, with several modifications. Here are some pictures, with the details after the jump:
As you can see, there are several changes from the original design. I am using a Klipsch RC-62II center, which has a depth of 12.8" and weighs ~ 30 lbs. Since the rear of the speaker is supported by a single foot which applies force to the rear center of the glass, only supporting the shelf from the front and center would be quite haphazard. Imagine pushing down on the very rear of the shelf - it would want to lift away from the front and tilt back, with the center bar as the pivot. To combat this tendency, I added two short bars which extend to the rear of the glass to support the back corners, while eliminating the unnecessary lower cross bar. I also did not drill holes or use screws to support the glass shelf. Simply sitting it on rubber feet provides more than enough friction to keep it in place. This also matches the rest of the media center (TV and A/V equipment stands use glass shelves that sit on rubber feet).
In order to put this together, I needed to place 3 separate orders: McMaster-Carr for hardware, Elite Custom Glass for the glass, and 80/20 (through a local distributor). The TV, by the way is a 60" Pioneer PRO-150FD, which has a 850x500mm mounting hole pattern.
Let's start with the 80/20, the hardest part. I actually had all the pieces machined rather than doing this myself, for higher precision and a more finished look. I used metric 25 series profiles (25x25mm), which made working with the dimensions quite a bit easier. There are 2 vertical bars, 1 horizontal cross bar, and 2 short cantilever bars, with the associated hardware. The horizontal cross bar is 825mm long - the centers of the vertical bars are 850mm apart and we need to subtract 12.5mm from each side for the additional width of the bars themselves. It only needs one T-slot, facing down. For the vertical bars, I measured from the center of the bottom mounting hole to the top of the TV. Then, we need to subtract 25mm from this length, because we are sitting the 25mm wide cantilever bars on top of the vertical bars. We also need to add 25mm to length to account for the bar extending down past the center of the bottom mounting hole. As you may notice, these cancel out, so just use the original measurement. For me, this resulted in a length of 688mm. Two T-slots are needed, one facing the rear of the TV (to attach the cantilever bars) and one facing the inside (to attach the horizontal bar). I also had 11 mm drill holes machined (at 25mm and 525mm from the bottom). The short cantilever bars (extending toward the rear of the shelf) are probably the most difficult measurement. I measured from the front of the TV, where the glass shelf would "start" to an imaginary vertical plane flush with mounting holes on the back of the TV, where the cantilever bars "start" (working towards the rear of the TV). We subtract this measurement from the depth of the shelf, and, allowing for some overhang, subtract about another 1/4". You also need to account for the thickness of the standoff washer, so subtract another 3mm. For me, this resulted in a length of 205mm. Only one T-slot is needed, facing down. Throwing in some endcaps and gussetted corner brackets, plus black anodizing on everything, and here is my 80/20 order:
Next, the hardware. We'll need thick washers to sit the bars slightly off the rear of the TV, thin washers that go under the head of the mounting screw, mounting screws, and rubber feet. The mounting screws are M8 socket head cap screws. Pioneer recommends 12-18mm of thread engagement, and between the head of the screw and the mounting hole, we have a thin washer (1.5mm), a thick washer (3.5mm), and the aluminum bar (25mm). So allowing for 15mm of thread engagement (leaves room for error), we arrive at a 1.5+3.5+25+15 = 45mm long screw. The washers are trivial, we just need to worry about the inside diameter clearing the thickness of the screw (8.3mm). You can use whichever rubber feet suit your fancy. Here is my McMaster-Carr order:
Finally, the glass, the easiest part. I chose a depth of 13" to accommodate the 12.8" deep speaker with some room to spare. As far as the width, the mounting holes are ~33.5" apart. Allowing for the added width of the vertical bars (12.5mm x 2) and some overhang (about 1/4", apologies for mixing dimensions here), I arrived at 35" of width. I ordered a 35" x 13" x 1/4" tempered, black piece of glass with a flat edge polish, to match the TV stand.
I placed four rubber feet spaced across the length of the horizontal bar, two at each of the back corners, and four on the glass itself (the edge that sits on the TV).
And there you have it folks. Putting this all together took about 15 minutes and is easier than assembling any piece of IKEA furniture. Doing extensive research of the 80/20 catalog (first time using the stuff), and triple-checking all the measurements was by far the biggest pain. I hope that this post helps and encourages someone else to do the same thing and saves them a bit of effort! Feel free to ask any questions you might have ...