Thoughts on this DIY flexy rack?

[aprather]

Im about to receive a new amp and pre-amp and want to build a nice AV rack (that will also hold my center channel speaker). Here is a current visio rendering that I have just created.

The center is about 50lbs, the amp is 115lbs. I plan on using high quality pine (3/4" to 1" thick) and staining it to a nice rosewood finish. The poles will be threaded rod (as per flexy specs).

Please give me some tips/suggestions

http://members.cox.net/aprather21/avrack.jpg

Thanks!

[SVonhof]

When I made my Flexi style rack, I decided to try to stop vibration from getting transfered from one shelf to another, so I used stepped washers so that the threaded rod would not be touching the shelves (step would go into the hole and the rod would be smaller still).http://www.vonhofs.com/theater/sm_10-31-01_flexi-rack_3.jpg Good concept, but the washers allowed too much wobble to the rack. I would instead reccomend going with some larger all-thread rod, such as 5/8 thread or something and just use regular washers(or just the nuts) and call it a day.

Do you plan on using 4 holes per shelf? I wanted to get three points of contact/support for each shelf (3 points make a plane, right?), but the problem was that I went with the two on the outside of the sides and one on the inside of the outer shelves, so that I had to have another rod on the back of the center shelf section. Worked, except that I didn't offset the ones on the inside of the outer shelves, so that the center shelf section had two holes in the middle of the edges and one in the very back, so that if I put too much weight toward the front of the middle shelf, it wanted to tip the whole thing.
Since I am sure that was about as clear as mud, here are some images that might help clarify:
http://www.vonhofs.com/theater/sm_10-31-01_flexi-rack_2.jpg
http://www.vonhofs.com/theater/sm_11-17-01_rack.jpg
http://www.vonhofs.com/theater/sm_3-18-03_mniplex_13.jpg
Basically, for the support rods, going from left to right, I had two in-line, one, one, one, and two in-line.


BTW, I never liked the Flexi when I was done, so I replaced it with a new rack that I built based on the idea of the other Salamander design, the Synergy:
http://www.vonhofs.com/theater/2-12-04_Theater_22_sm.jpg

[aprather]

Hi,

Yes, I plan to go with thicker rods, probably 5/8. And I also plan to do 4 holes per shelf. Ive updated my design and it looks very close to your original one. I plan to use 5/8" galvanized nuts (which are pretty big) and washers to seperate the top shelf from the ones right under neat it. I also may add rubber washers for vibration absorption.

How deep did you make yours? 30"? Also, is there a reason you didnt use a long single peice at the bottom instead of 3 individual peices? Was that just preference?

Here is an updated drawing:

http://members.cox.net/aprather21/avrack4.jpg

Thanks!

[SVonhof]

The wood I was going to use didn't come in lengths longer than 42" (it is 1 1/4" thick pine, bucher block style) and I was making my overlall length almost 95". Because of that, I went with three individual shelves.

BTW, check www.McMaster.com for the nuts, washers and all-thread. They have stainless on there, which gives a slightly cleaner look, for more money though and they will deliver to your door via UPS.

[shaun@au]

Sorry to hijack an old flexy-thread, but it seemed like a better idea than starting another one :)

Here's my first attempt at a flexy, mostly to see how it'd turn out:
http://www.users.on.net/~whatdot/images/75-Flexy.jpg

I've now decided to make a flexy-style entertainment unit, with 8 shelves (to hold my growing collection of gear), TV, centre speaker, and DIY portable screen.

It was assembled just to check everything fits together:
http://www.users.on.net/~whatdot/images/77-BigFlexy.jpg

Then dis-assembled so it can be varnished (same as the first rack).

Construction on both racks is using 18mm MDF with 3/4" threaded rod (zinc-plated steel) & washers & nuts. If I get a bigger centre speaker, I'll need to reinforce the top shelf - probably by using thicker MDF.

[kthomson]

You might consider using 3/4 cabinet grade plywood instead of pine. It's cheaper, it's stronger, it's stains better, and the edges can be finished with oak veneer edging to give it a finished look. Oak veneered plywood is about $35.00 a sheet at HD or Lowes, and they will rip it to width if needed.

[Tweak]

I also may add rubber washers for vibration absorption.

I would recommend against doing that. While on the surface it seems like a good idea, it conflicts with what should be the primary goal of an audio rack: being rigid and low-mass. The rubber washers would serve to isolate the shelves from one another to a small degree, however, what you gain in isolation you'd more than lose in compromised rigidity.

You can always isolate your components from the shelves, but there is little that can be done to address deficient stiffness in a rack. Also, the rack can easily be isolated from the floor (a sandbox being just one of several methods). If the rack is isolated from the floor, and the components isolated from each shelf, the vibration passed from shelf to shelf will be minimized beyond what rubber washers could do.

I agree that pine is not a very audiophile-friendly material. Oak ply is a good chioce, but my favorite is birch ply. Of course, I subscribe to the theory that the best shelf is no shelf, which is why I designed and built a shelfless rack out of composite materials.

-Tweak

[SVonhof]

BTW, I know the post that Tweak is talking about is old, but I wanted to second the idea of not using rubber washers. I used some stepped washers for isolation (the step fit into the hole in the shelf and had a smaller thru hole for the rod) and my flexy rack was flexing all over the place. It was only a few shelves high which didn't help, but it was not stable at all, one reason why I replaced it with what I have now.

[shaun@au]

I'm just using the steel washers - both my racks are pretty solid when empty, and totally inert when stacked.

[Tweak]

When I talk about stiffness in a rack, I'm assuming the concern is sound quality.

If you don't think vibration can negatively affect audio gear, I respect that opinion, but my words won't make much sense. Just label me a quack and move on....

It's very easy to build a rack that's incredibly stiff and strong. That same rack, however, could make your gear perform poorly. Being stiff enough to safely support your gear is not enough. It needs to be as stiff as possible, and as light as possible for the stiffness achieved. Being light and stiff raises the resonant frequency of the structure, and therefore reduces the magnitude of vibration during resonance. Also, as most isolation devices are low-pass filters, keeping the resonant frequency of the supporting structure as high as possible helps the isolation devices do their jobs.

When I was using a flexy, I started out with steel rods and washers. A distinct improvement in sound quality was achieved by switching to larger diameter aluminum rods and aluminum washers (I doubled the washers when I switched to aluminum to help maximize stiffness - I also eventually glued the washers to one another and to the shelves - increased stiffness with very little additional mass).

As noted above, switching to a shelfless composite rack (which was lighter and stiffer than the flexy) brought about a very nice improvement. I will never go back to a rack with shelves.

-Tweak

[SVonhof]

Hey Tweak, I know your new rack is not a Flexy, but do you have pics to show us? I want to see what you are talking about when you say shelfless.

[Tweak]

I don't have pics accessible to me here (only at home), but I'll describe it for you.

The basic structure is three vertical columns spaced out appropriately to accomodate my largest piece of gear. The columns are held together by horizontal beams - one set of three beams just below where each shelf would be if I were to use shelves. Between the beams at each corner are joists - the joists both stiffen the structure and provide a place to mount spikes (pointed upward). This comprises the rack structure.

For each component in the rack, atop the spikes I have a DIY constrained layed platform (a-la Symposium). Atop the platforms are DIY rollerbearings and the components sit on the rollers.

So, this essentially looks like a three-legged shelf-equipped rack, except instead of shelves I have spikes on which platforms can be placed.

-Tweak

[nirvana_av]

[QUOTE=Tweak]I don't have pics accessible to me here (only at home), but I'll describe it for you.

The basic structure is three vertical columns spaced out appropriately to accomodate my largest piece of gear. The columns are held together by horizontal beams - one set of three beams just below where each shelf would be if I were to use shelves. Between the beams at each corner are joists - the joists both stiffen the structure and provide a place to mount spikes (pointed upward). This comprises the rack structure.

For each component in the rack, atop the spikes I have a DIY constrained layed platform (a-la Symposium). Atop the platforms are DIY rollerbearings and the components sit on the rollers.

So, this essentially looks like a three-legged shelf-equipped rack, except instead of shelves I have spikes on which platforms can be placed.

-Tweak[/QUOTE]


Now we definitely have to see a picture :)

[Tweak]

I'll try to remember to log on and post some pics tonight. Sorry, I didn't go anywhere near the PC last night.

-Tweak

[D_B_0673]

need a pic. I can't visualize what you are describing???

[Tweak]

Will you settle for a crude Paintbrush drawing?

The red dots represent the spikes on this two-component version. You could forego the isolation devices and mount the components directly on the spikes.

http://home.comcast.net/~pburant/images/shelfless.jpg

-Tweak

[D_B_0673]

Thanks that helps, although I wonder about spikes into the bottom of heavy equipment. That is a lot of weight on a very small surface area

[Tweak]

Here's the real deal (sorry it's not more clear). Don't mind the clutter or the el-cheapo VCR on top:

http://home.comcast.net/~pburant/images/rack.jpg

As for heavy equipment, it's not an issue for me since I use rollers under my components. If I needed more weight-bearing capacity, I could just increase the size of the ball bearing.

A lot of spikes will ship with a puck (normally used to prevent the spike from digging into a wood floor, sometimes called a foot pad). You could use the pucks between the spikes and the bottom of a heavy component (and the puck would not need to be adhered in place - gravity will keep it still). Actually, you reminded me that since some of my contrained-layer platforms have wood bottoms, I used these pucks between the spikes and platforms, just as I'm suggesting above. To make life easy for myself in case I ever wanted to move things around though, I did go ahead and epoxy the pucks to the bottoms of the platforms.

Here's a link to the spikes I used. Note they are very inexpensive, but by no means cheap :-)

Brass Spikes (http://www.kalapanadesigns.com/)

-Tweak

[strongml]

The flexy rack is a very flexible design in terms of style and options. In one of the local tweeter stores, i noticed they used 10 or more of them in one of the HT rooms, all painted matte black. I built one for my living room to hold the (unfortunately small, but very heavy) 27" sony crt, and a few other components. It's quite solid and on large industrial casters. The casters were purchased from Home Depot and come with 3/8" threaded bolt ends, they're for a rigid table saw it says on the package. I prefer to use 3/8" all thread without washers. Four 3/8" all thread with plate washers on top and bottom provides plenty of strength for the shelf I'll post a picture of in the next post. Just be sure you torque all of the nuts equally tight and level each shelf as you assemble.

[strongml]

3/4" baltic birch ply stained with 2 coats rosewood stain
birch veneer tape left natural before clear coat
everything covered with 4 coats clear gloss
all waterbased minwax products
used 3/8" rods, plate washers, 3/8" nuts, and cap nuts for top,
3/8" couplers used to attach casters to all-thread.
panels were purchased pre-cut at Home Depot.
Total materials cost $195.00
http://ladenstrong.com/flexyshelf1.jpg http://ladenstrong.com/flexyshelf2.jpg

[shaun@au]

Looks good :)

[shaun@au]

Finally finished varnishing my Flexy HT Stand (as above):

http://www.users.on.net/~whatdot/images/88-BigFlexy.jpg

[cpotoso]

now *my* flexy rack (see attachment)... It took a while to thread all the nuts :)

[IMG]

The equipment is:


Yamaha YHT-755 (dvd carousell and receiver, one of the main speakers and the sub are also seen)
cassette deck (bought at garage sale for $4... just for the occasional old tape...)
please disregard old tv and vcr, we use a DLP for movies!)

[maxse]

guys how hard is it to actually build one of these things? I am considering it very much. And also what does it mean to Varnish? Is that just to stain the wood? And how easy it is to do that so that its shiny? In addition what material should I get from HD and the width in order for this to work. I need about 6 or 7 shelves. Also how would I cut the threaded rods to the size that I need? and are they strong enough and straight? I would really apprciate some help and please as much detail as possible. Also what should I expect the cost to be? I am looking to spend about ~$80. Is this possible? Thanks everyone for your help in advance.

Also how would I cut the holes in the wood for the rod? And what type of wood? Thanks everyone so much, if this is easy I am going to be soo happy. Thanks.

[SVonhof]

Dude, you have too many questions!

The rod is called all-thread and is available in all the normal thread sizes normally in stainless steel and zinc plated steel. In the larger sizes, it is typically very straight, so you don't need to worry about that. If you want to keep the cost down, stay away from the stainless steel all-thread, nuts and washers, since the zinc is much cheaper.

As for cutting the holes in the wood, typically a bit such as a spade bit will work fine as long as you have a peice of scrap wood below the peice you want to use, so you don't blow the other side of the wood out (drill through both peices that are clamped together). You could also use a forstner bit, but that is overkill as the holes won't be seen after everything is assembled and you HAVE to use a forstner bit in a drill press to get the best results.

If you want this all to be easy, you may want to have Home Depot cut all your wood for you since they have the panel saw (make sure it is working that day) and can make all the cuts for you. They do not garantee that the cuts will be accurate, but it may be good enough, that's for you to decide, you may need to make finish cuts on your own at home. The material you want to use depends on what you want the finished product to look like, since you can go with plywood or even thick peices of MDF if you wanted to, but the finish look will determine what type of wood you should use. Varnish is a type of finish that you apply to wood.

BTW, if this is your first project (it seems like it based on the questions) it shouldn't be a hard one and will allow you to buy a few tools if you don't have them already. Also, it will be an easy learning project, just make sure to take your time and follow the proper safety precautions with the power tools and wear all the proper safety gear.

[BigguyZ]

For finishing- use scrap wood to experiment what type of product you want to use.

[maxse]

Thanks guys, Yea SVonhof a lot of question I want to make sure I do this right. Im still not sure what I should use for the "feet" of the rack to stand on. And also what thickness of plywood should I be going with here. Also how easy is it to apply varnish to plywood? And what about the edges? Do I also need to get rubber washers in addition to the regular ones? Also I dont have a clamp or a vice so I am going to have to drill each one individually. What distance from the edges should I be drillling the holes?

[SVonhof]

If you don't have a clamp or vice, I would suggest spending a few bucks on some cheap clamps from Harbor Freight or something. You need to use a scrap peice of wood on the back-side of the plywood or you will get some splintering. You probably only need two clamps.

As for distance from the edge, just don't get it too thin, I would think if you left a minimum of 3/4" material at the edges, that would be fine. Whatever size washers you get, make sure they don't hang over as well...

As for varnish on plywood, depends on the type of plywood, but it should be fine. The edges can be left as-is and just finished at the same time as the rest of the plywood or if you feel so inclined, you could add either wood tape (requires you to iron it on and trim it afterward) or wood strips with mitres on the ends where they join.