Built a Flexi-type rack?

My "flexi" was built using 2" maple, sized at 24" x 24". My upright support rods are 3/4"-10 threaded brass from McMaster-Carr, with all brass fittings - nuts, washers and top acorn nuts. For the spikes, I used Audio Points (model 2.0AP-1OINT). I have four shelves and a total height of 48 inches. The rack weighs in at around 300 lbs, and sits on a fiberglass reinforced concrete basement floor. Holes were cut in the maple using a 13/16" forstner bit. Rear legs offset toward center by 1" (each side) from the front legs, mainly to break up vibrations as a result of symmetry (think of a perfectly square listening room and the resulting sound - I believe the same problems occur on a much smaller scale vibrationally in a rack). I had prototyped several flexi models using steel rod and hardware, and several types of shelf material (furniture grade plywood, MDF, several composite laminates, etc) but found the thick maple to perform the best. I also believe brass to be one of the better metals to use in audio applications (there are numerous discussions online as to the relative merits of various metal types for audio use). Personally, I found that rubber-type damping materials either as through-hole bushings or as spacers between the washers dampened the sound to a degree I personally didn't care for, and seemed to detract from the overall dynamics of the system. Since I utilize brass Audio Points under all my components on the rack, the coupling/mechnical diode effects of the points seem to form a synergistic relationship with the rack itself, and measurable vibration seems nearly nonexistent. Of course, YMMV depending on existing substructure (wooden floors, etc), other types of isolation products already deployed, and personal taste. Happy building.

-Richard

As I recall, the final cost of materials was right around $550 - a simple breakdown was $275 for the maple (sourced from a local millworking company), another $125 for the brass audiopoints, and around $150 or so for the brass bits from McMaster-Carr. A similar rack from Mapleshade is right around $1000 + shipping. The basic differences are in upright diameter (1.25" steel on the Mapleshade vs. my .75" brass ), and in the shelf dimensions, where I use a 24" x 24" shelf, the Mapleshade uses a more "standard" rectangular audio size of 24" x 15". I also dispensed with the Amish craftsmen ;-))

-Richard

I would like to point out that I constructed this rack about three years ago. With the wild upward fluctuations on the world metals market, I am not at all suprised by the price quotes on the raw material. Material such as copper has nearly doubled in price over the past 4 years, and wood seems to rise continuously in price. Last night, I dug up the invoice for the brass - $178.44 (so I was off by $25), but still this is indicative of how much the price has risen over the past few years. BTW, my invoice shows $31.14 each for the threaded rod - a considerable increase to $47 each!! I'm in Albany NY, and actually sourced the material through a millworking company outside of Utica. I'd recommend them, but since I'm trying to be helpful, won't - since they were a pain to deal with. Nice product, but it took forever to complete. Cheers,

-Richard

Measure twice and cut once! When I drilled my shelves (on a drill press which I know to be mandatory - it is nearly impossible to cut a perfectly perpendicular hole with a hand drill), I made a small jig out of thin aluminum, which guaranteed the position of the hole - just align it to the corner, and go. I think the most important aspect of cutting the hole is to use the right speed, and the right bit. As I said, I went 1/16" above the rod size to get a little play, and used a brand new forstner bit (most will state the correct speed for the material you are cutting), which gave me perfect cuts - no splinters or tearing of the grain at all.

My problem with most commercial products, and hence the impetus for building my own, was the near ubiquitous use of tubular material which rings like a bell. Who the hell wants to fill a rack with lead or sand? Commercially available racks in the price range we're looking (or building) at, are built to a price point, and are filled with compromise(s). There are many exceptions, but we begin to start talking serious cash. I also think it quite nice to be able to customize your dimensions, your choice of materials and finish, and to make the rack a customized unit that suits your needs. I also find great joy in building things myself - pride of workmanship, if you will. My rack seriously outperforms (sonically) everything I've heard under the $1000 mark (and of course I've not heard everything), but as a bang for the buck DIY project, I don't think you'll ever look back.

The aluminum (or whatever material) jig doesn't have to be square - simply consistent - though being square certainly helps align to the corners of your workpiece. Mark the jig as to what the top outside corner should always "key" to -- in other words, if you use a square jig, and don't mark it for consistency in alignment, there will always be some margin of "play" in the way the workpiece is marked/drilled since you may inadvertently rotate the jig during workpiece marking. I used a 3" x 3" piece of aluminum with a thickness of around .0625" (1/16") , and cut a hole to size that matched (and some) the diameter at the tip of the forstner pilot arbor. This ensures that ALL the holes will line up consistently, since the pilot on a forstner extends perhaps a quarter inch below the actual cutting head. Be sure to mark (with tape et al) which side of your workpiece is your top, and then mark the edges (front or back). I tend to pick the best finish on any given workpiece, and then go from there. Since no piece of material is ever truly square in all dimensions, it helps to start at one corner, and "jig" around the workpiece clockwise so that each shelf is consistently marked and drilled. As long as everything is marked and well-planned, you'll have no problems.

-Richard

John,

Nice score on the brass. I figured that since the final weight of the rack was in excess of 200 lbs while fully loaded, there was no need to firmly tighten all of the weight-bearing brass cones - the sheer weight of the rack alone would provide sufficient coupling in this instance. What I did was thread them all the way in (flush to the bottom brass nut on my rack), and then slowly loosened the sagging corners (in effect raising that corner). My basement floor, while ostensively level, was in practice nothing of the sort. I came up with a perfectly level bottom shelf, and levelled everything else from there. McMaster-Carr also has laminated brass washers in the requisite size that are layered in .01 inch increments. These allow firm coupling of the cone to the rack hardware, and can be trimmed in thickness (by peeling off layers) so that firm coupling can be achieved. I used these layered/laminated brass washers when installing the AudioPoints on the bottom of my speakers to great effect. Happy listening,

-R.