DIY Ball Bearing Isolation

[jp11801]

Ok I have read a bunch from Barry Diament about ball bearing and air bladder isolation and I want to take the plunge.

Here is what I am trying to find but without the high audio price tag

any ideas where I can find stainless steel cups like that and very hard ball bearings? These are like $180 for a set of three and I am hoping to source something like it for a lot less. Any ideas?

[CarlSeibert]

Do they have to be concave? Could you just constrain the ball between two plates and pen it in with an o-ring glued to one of the plates?

[jp11801]

according to the man concave with no flat spots

[nikongod]

You can get ball bearings in a wide variety of materials & sizes from McMaster Carr (McMaster-Carr)

Here are my DIY isolation feet.

(taken from the recent NYC meet thread)

They are IKEA votive/tea lite candle holders

LINK

And squash balls which are available in several hardness grades and whatnot. I use double yellow dots, the softest/least bouncy.

[jp11801]

Ari thanks for the tip on the bearings now I just need the cups. The squash balls are cool but I am trying to test out this thing as the results for speaker isolation is said to be great. The catch is you do not want to be drunk and knock into them.

[grawk]

You better avoid that then

[Voltron]

Seems unlikely that JP could avoid that.

[crappyjones123]

if the sandwich plates were flat then is there anything to stop the speaker from just rolling off on the ball bearings. i think the concavity holds the ball bearing in place not allowing it to move around. just my thoughts.

wait, for some reason i forgot the whole o ring part. if the o ring is too tight, the bearing will ride the o ring and depending on how heavy the column of weight above any o ring, the bearing might go deeper in some o rings vs others. if the o ring diameter is too big, the bearing will have room to walk.

[CarlSeibert]

My thought was the flat plates (in addition to being easier to source) would provide no resistance to lateral motion, which seemed at the moment to be the idea, while being solid up and down. I figured the o-ring would prevent the whole affair from walking off the plate. But then I guess it might just walk until it hit the o-ring, in which case you would have a resistive/reactive affair based on the elasticity of the o-ring being squashed under the ball.

Now I see that the idea is more like a pendulum. As the system displaces sideways, it lifts whatever is sitting on top of it and a moment later gets pushed back to its neutral spot. Which suggests that choosing and then achieving the right resonant frequency is the trick. Which, in turn, would require math. Oh dear. That brings us back to Jim's original method - find parts of the same dimensions as an example that already works.

I like Ari's idea. Glass and ceramic objects can be concave and they're pretty hard. And who doesn't love Ikea?

How about a negative meniscus lens? Eyeglasses are almost all plastic nowadays, but maybe at a place like Edmund Scientific?

I don't know how hard it is to make ceramic objects of the hard sort of material, or if it's really hard to hold tolerances, but a school with potters might be a resource.

I asked my wife to inquire around her jeweler friends to see if zirconia spheres are reasonably priced in that market.

[The Monkey]

This is cool. Science, DIY, and danger! Looking forward to seeing how this turns out. I predict that Nums will get it right. And promptly thereafter, in a drunken celebratory dance, he'll knock those fuckers over.

[Dreadhead]

2 plano-concave lenses and a good quality ball bearing?

Plano-concave lens, standard grade

http://rolynoptics.thomasnet.com/viewitems/simple-lenses/plano-concave-lenses?&forward=1

Glass should be plenty hard enough and the lens will have no hard spots. Would look pretty cool.

Edited March 15, 2010 by Dreadhead

[Dreadhead]

2 of these:

Item # 12.0010, Plano Concave Lenses on Rolyn Optics

10 Loose Balls 1/4" = 6.35mm Ceramic G5 SiC:Ball Bearings:VXB

You could call them black oysters

[grawk]

12 of the lenses and 1 of the 10 ball lots, minimum, if it's for 2 speakers

[Dreadhead]

I was saying for 1 but yes you are correct..

[grawk]

Ends up not being a very economical isolation system

[Hopstretch]

Ends up not being a very economical isolation system

Compared to the very-reasonably-priced commercial alternatives?

[Dreadhead]

Ends up not being a very economical isolation system

Very true but it is significantly cheaper than the commercial one. Also those lenses were likely overkill, I found several in the $3 price range but they had a lot less center thickness which I thought might be important.

[Dreadhead]

here this will likely work too:

AMEP - Product Details

[Voltron]

How about rubber?

Or a metal cap with a concave bottom?

[crappyjones123]

jp how heavy are the speakers?

i am assuming that the ball bearings on glass will have a single point of contact which would concentrate the weight on to one spot of the lens instead of distributing it over a surface. would make it easier to break.

would make sense to do it with some kind of pliable balls but again, one ball might get squished more than the other depending on the column of weight above it. wouldnt have that problem with ball bearings.

this is turning out to be a cool math problem

[aerius]

If you want an ultra cheap solution, cut the bottom inch or so off some pop cans and fill them plaster or epoxy, this will give you the concave surface for the ball bearings. Overfill the top edges by a bit to cover the sharp edges on the cans, stick a large marble or ball bearing between a set of can bottoms and there's your ball bearing isolation device.

[jp11801]

thinking of using concave furniture sliders found at home despot

[CarlSeibert]

this is turning out to be a cool math problem

That's easy for you to say

If you want an ultra cheap solution, cut the bottom inch or so off some pop cans and fill them plaster or epoxy, this will give you the concave surface for the ball bearings. Overfill the top edges by a bit to cover the sharp edges on the cans, stick a large marble or ball bearing between a set of can bottoms and there's your ball bearing isolation device.

I was thinking sort of the same thing, but filling the back side of the negative lens with JB Weld. That should (hopefully) support the glass well enough to keep it from breaking unless the load gets pretty large. Hmm. I wonder if epoxy would be hard enough? You could mold a positive lens - or anything convex - repeatedly into epoxy to make multiple parts.

I wonder if you could achieve the same result by hanging the load from short cables or fancy high-zoot fishing line? This thing seems fairly pendulum-like, so why not try a real pendulum? That might be better suited to an application that wants an isolation platform, rather than feet, but it's a thought.

And I just noticed I somehow thought the OP was morphsci. Humble groveling apologies.

[crappyjones123]

pulley ratchet arrangement leading to a suspended pair of speakers...thats sounds infinitely more fun than this silly ball bearing business. having the speakers suspended will also lead to being able to change the angle of inclination a lot easier and with smaller steps than perhaps with a ball bearing. i think jp might have created a whole new business opportunity by starting this thread...fishing line rolling "my fishing line gives tighter bass than yours!" imagine the fun that could be had with the average head fier!

[jp11801]

thinking of using a very hard wood and having concave discs made Concave Areng Wood Plugs 1.34" inch 34mm (p1011) - eBay (item 170296851330 end time Mar-19-10 15:58:20 PDT)

or

Edited March 16, 2010 by jp11801