Vibration isolating rollerballs

[jabbr]

There has been a great deal of discussion vibration isolating rollerballs on the thread started by YashN and a specific design offered by Barry Diament in this post: http://www.computeraudiophile.com/f8-general-forum/equipment-isolation-and-vibration-damping-24805/index2.html#post436931

 

tne found this: http://www.computeraudiophile.com/f8-general-forum/roller-type-vibration-isolation-devices-info-24991/#post440832 and I contacted Mike: http://www.computeraudiophile.com/f8-general-forum/equipment-isolation-and-vibration-damping-24805/index13.html#post441283 I misquoted the price for the 6061 material: he told be $85/set (not $75).

 

We should have the numbers to get the 20 set minimum price of $130/set (6 blocks). He's ordered 7075 product and needs to retool for the job so we are looking at August at this point.

 

So we can keep track of how many sets (and confirm the 20 set minimum) we can list the orders. Email Mike at [email protected] to arrange shipping and payment.

 

Jon

 

Username # Sets 7075

jabbr 12

[jabbr]

Right 6 pieces per set and the price is for everyone here assuming we have a minimum of 20 sets -- we are there already assuming everyone whose told me they want a set commits-- you can throw away the chrome steel bearings if you like -- they are very cheap.

 

I've just arranged for this with Ingress. Everyone can email Mike and arrange shipping and pay.

[jabbr]

Actually, maybe jabber would allow me to measure a set of his, he's signed up for 12 sets!

 

Sure I guess -- I'm keeping 6 sets and a friend of mine is keeping 6 -- we are getting these and then testing out different bearings -- probably my network switches and NAS will keep the chrome bearings but tube amp will get Silicon Carbide (or Tungsten if his uncle can get us a good deal)

[jabbr]

I believe a set is 6 pieces (3 tops and 3 bottoms) and 3 bearings. In terms of price, I'm reading it as each set is $130 , assuming the group collectively buys a minimum of 20 sets.

 

Yes

[jabbr]

Jon,

 

Is this the Group Buy thread ? It doesn't say so in the thread title ?

 

Sorry, but I'm confused about your prices for a set (3 or 6?), and the minimum. Is that for each buyer, or for all combined ?

 

I suggest that the project only do the bearing blocks and forget about the bearing balls. I think it would be better to let each individual chose what type of balls they want (SS, TC, ceramic), with links to the best sources.

 

I don't intend to take any payments myself or handle any shipping -- I just cajoled/convinced Mike @ Ingress to retool & get some 7075 for us at a good price. I have no relationship with Ingress other than good customer:)

[jabbr]

You want to measure Jon's balls?

 

Use to have brass, switched to carborundum

[jabbr]

For better isolation, you'd need the shallowest curve possible. Large recipients would allow that.

 

Personally, I'd use a flat dish, with curves at the very end to prevent falling off of the bearing. Proposed that mid-thread or so, after John Swenson's gedankenexperiment. Experimented a bit manually with my girlfriend's pancake pan.

 

There are all sorts of tradeoffs. I am going to experiment with ceramic dishes with a lip for this reason.

 

From a practical point of view however, the bowl keeps the ball bearing centered. You can use one set of bowls and a flat upper surface, or invert the bowls for even better stability. That's why the bowls come in sets of 6. Once you have them you can use them as you like.

 

After some back and forth, including my offering to find a cheap supplier for 7075, at the quoted price, Mike will do the 1" bowl (0.96) with a depth of 1.8mm (as per Post#30) with an overall diameter of 1.5" and a depth of 1/2". He states that he is using high quality 7075 US supply which will alone cost $40/set. This is in my opinion a very good price given the desire to maintain the highest quality -- and in my experience having a better quality 7075 is very valuable.

 

So in any case while I do really like AnotherSpin's design, and all else being equal would use it, Ingress has ordered 1.5" round 7075 stock based upon the specs I originally gave (what Barry suggested), and so we are limited from a practical point of view to a 1" bowl (leaving 1/4" of material around the bowl).

[jabbr]

There's no benefit for the purpose of isolation that the ball is kept centered. On a flat surface, it could still be off-center and the isolation would remain operational (and optimal).

 

Right. The benefit is for those of us with kids and/or dogs and/or intoxicated friends who might be inclined to roll a speaker or other piece of heavy equipment, right off the stabilizers and onto the floor, thus creating both low frequency vibrations as well and a strong audible shriek from my wife whose self sustaining echos will not be damped by any mechanism discussed here nor known to physics -- it might only response to powerful pharmacologic agents but again, the entirely flat design would not be optimal under the circumstances in my own environment.

[jabbr]

jabbr,

 

What is the diameter of the curvature of the bowl ?

 

I take it that the the cheaper 6061 alloy is no longer an option ?

 

I quoted 1.8mm -- that's actually 1/8 inch depth. section of a 2" sphere. So diameter 2".

 

Much of the work involved is in setting up the machining. I suspect that there would need to be some minimum number of sets for a run of 6061 but he may keep 6061 in stock. I'm interested in 7075. If people are also interested in 6061 we could use this thread to get a rough number and then ask Ingress.

[jabbr]

For us, visuals, is it possible to see how selected design for group buy may looks a like? And, no discussion here? No input (possible) from Barry?

 

You are the only one who has ever provided a drawing! I'd be happy if you converse with Mike [email protected] and come to an understanding of what is possible given the constraints of what he's ordered in terms of material and reasonable price. Mike wants to make something that we like. I'm happy to go with either the spec Barry gave us already, or yours if that meets the manufacturing constraints or something in between.

[jabbr]

I have pledged 3 sets.

 

About the design, if you see Mike's website, he has one that has edges chamfered. This will possibly give some visual oomph.

 

Some possibilities:

1. Small radius on the edges.

2. 4mm of the bottom of the disk could be left un-mirror finished. This will give some definition to the disk.

3. Else we could have some lathe groove at the 4mm mark, that would be cool too.

4. Or the bottom 6mm could be provided with concentric groove every 1.5mm, hence 4 parallel groove.

5. The top should definitely be mirror finished to allow for full isolation.

 

Can do cadd drawing if required.

 

BTW, Carbide Ball can be sourced from China. ~5 USD each for 12mm dia.

 

I would like to have a mirror finish on both sides of the bowls -- that way they can be used either against a flat top or inverted.

 

Where can you get carbide for $5 12mm bearing? That's an excellent price!

[jabbr]

I found a Delaware supplier of half-inch TC balls at US$3.25 per ball, see https://www.craigballsales.com/1-2-12.700mm-lot-of-10.html.

 

I do not know them and have no idea of the grade of the balls, i.e. G25 or else.

 

My apologies if that has been covered in other threads, and I do not recall it has, but is there a benefit in having the ball and the bowl, cup, or disk as I call it, made of the same material of the same grade? My quasi non existent knowledge of metallurgy makes me think that having both made of the same material of the same grade should produce better results than otherwise. The probability that the desired properties of one be limited or defeated by those of the other of another material would be minimized. Does this make any sense? Am I splitting hair here?

 

I posted this while I had time today but will not have much time later today and tomorrow to read your replies, if any. I will of course catch up as soon as I can either late Sunday night or Monday at the latest.

 

Many thanks in advance, and have a great weekend. Happy Independence Day to our US friends!

 

Gilles

 

Thanks for the link -- at those prices for Tungsten Carbide I'm getting a few to try out -- I'm also getting a few from that TaoBao link -- it was actually fun to navigate the site in Chinese with mostly English translation -- I actually had to figure out the symbols for USA at one point because the menu didn't translate:) we will see if the balls come as well as how round and smooth they all are. Maybe someone wants to compare them blinded for me:)

[jabbr]

If you think you've 'been there and done that', then it seems you have settled for a largely sub-optimal implementation.

 

Sub optimal is ok -- no bowls and we have nothing to group purchase:) I have no doubt that with a bunch of time and energy we can come up with something better -- Barry even has his own "iteration #2". That's ok because I just want *something* that is reasonably good that I can widely implement. I'd like to use this now and then test this baseline against improvements. I suspect that the improvements are more likely to involve vertical and these bowls will have a long and productive life!

 

 

Your impression that it is the curvature of the bowl that makes the isolation is wrong. That is a simple fact, and having the wrong understanding of how it works may lead you to settle on a sub-optimal implementation.

 

I strongly suspect that at the magnitude of the horizontal vibrations we are isolating, that the vertical displacement caused by the bowl curvature falls within the magnitude of vertical vibrations that also need isolation -- that is that the bowl acts as if flat from a practical point of view.

 

But I am more than willing to be proven wrong if data to the contrary is presented!

[jabbr]

The resonant frequency of such a system would be mainly set by the radius of the cup. Larger radius, lower frequency. A larger ball would have a bit less friction, and be less effected by the surface smoothness of the cup. Of course, cost, and size practicalities will enter into it.

 

Now I am referring to the radius of the sphere the cup would make if the curvature was continued into a complete sphere. So there probably is no optimum size, just a size adequate for whatever frequency you wish to reject, and practical in other ways. You can't use 5 ft diameter balls for instance under equipment even though it would have less friction. The shallowness of the curvature will need to be gauged against not allowing normal use of the equipment to cause the ball to roll over the lip.

 

Maybe for large scale deflections -- if I turn a slightly stiff potentiometer or flip a switch this causes a brief

Oscillation as the equipment settles down but for vibrations that are sourced from the ground -- I just don't see visible large scale deflections where I live -- I mean maybe for folks in Ca where there are frequent earthquakes but I'm not seeing this -- in fact you can measure the amplitudes with a laser but realize that the amplitude is highly magnified. For small scale vibrations I suspect the frequency response to be determined largely by other factors -- the bowl acts as if flat.

[jabbr]

Would a flat surface with a lip to prevent ball(s) rolling off allow more of the motions of cone drivers to result in unproductive reactive motions of the speaker and balls, in contrast to a curved bowl restricting those unproductive reactive motions to a greater degree?

 

A very practical benefit of spherical bowls is that they are not sensitive to leveling inaccuracies within the limits of the depth of the bowl -- the bearing always centers itself to the local minimum

[jabbr]

The evidence points to quite the contrary: I think you bailed out quite early of the original thread because you had 'difficulty following me' or maybe the rest of the thread, including the more sound theoretical and modeling aspects.

 

Yash,

 

I didn't mean to fork the discussion off your original thread where there's alot of great information and debate going on. I think I didn't name this thread properly, and regret that, as it was intended to be a group buy type thread for people interested in obtaining aluminum bowls at reasonable prices. I never intended that this be the only isolation technique, nor even that it is the "very best obtainable" rather something simple and practical for a group of people who wish to get some at a reasonable price.

 

I would prefer that the excellent discussion of new isolation techniques, and research into improved isolation techniques, continue to take place on your original thread. That's where I'm trying to post more theoretical responses. This has been a great and productive discussion.

[jabbr]

Hey, I thought we were talking about engineering balls, not wheels!

 

Alex -- turns out that smooth & hard balls make the Amber sing a pretty tune!

[jabbr]

Indeed I am argumentative, but I don't need to 'wonder why', I know why: it allows me to detect the bullshitters from the people who have actual knowledge, and then in the case my lack of knowledge is corrected by the latter, I don't get worked up at all and accuse them of unfriendliness or lack of civility: I learn something valuable from them and I thank them for it.

 

Confronting good arguments and facts is a healthy way of increasing one's knowledge about the world.

 

Learning is a win for me, but not for some others I can see here: easier for them to make baseless accusations instead of referring to the facts.

 

I'd rather be an argumentative and learning bugger than an ignorant bugger.

 

Why are you still replying to me?

 

Peace out!

 

No one is going to die from a few stray vibrations:)

 

Look, Barry has been incredibly generous by sharing his well tested and vast experience. There is a lot to be learned from experience.

 

You are also doing a great job highlighting a bunch of important and oft overlooked issues. You have a lot of creativity and curiosity. Keep generating ideas, some will live, some will die. That's how things work. Don't take any of this personally. If one idea doesn't fly, then launch 10 others:) If someone will die from a bad idea then fight hard. This is all fun.

[jabbr]

I've just been informed that Ingress is no longer interested in making the aluminum bowls to what I consider a reasonable spec. The proverbial straw was that he doesn't want to "spend an hour" polishing each bowl. The initial picture I was shown looked rather rough. I've got a bunch of tungsten carbide, silicon carbide and silicon nitride balls on the way, as well as a set of porcelain dishes and bowls on order, so a few things to play around until we can find a good way to get these made.

 

Barry, I'm still willing to pay extra for low serial number, signed bowls -- not the ones with a hole down the middle though well maybe :)

[jabbr]

Well, all might not be lost. I'm working on getting a test set of the bowls made and will inspect. They may or may not need to be additionally polished. One of the engineers at a firm that makes high end things for me tells me that they use 320-400 pre-anodization and wenol to polish after anodization. These bowls will be smoothed with Emory 320.

 

The tungsten carbide, silicon carbide and silicon nitride balls have arrived. They all look good to gross inspection. Tungsten carbide is *very* heavy. These are all $3-4 each. They are all round smooth and hard Don't expect that these are DoD spec but who cares? (I'm not spending $35/ball) 'sides the marble on the upper surface isn't mil spec either

[jabbr]

Hi Jabbr,

 

What might be the cost for these bowls?

 

I'm working with Mike at Ingress. He is making a set for me, smoothed with Emory 320 and I will check it out. I'm not sure if a mirror polish is needed -- this may work well.

[jabbr]

I found a picture of a stock Ingress bowl block and cropped it some, to show the bowl finish:

 

[ATTACH=CONFIG]19641[/ATTACH]

 

I too believe that the smoothness and concentricity of the bowls and balls are a big contributer to the quality of these type of devices.

 

That is the design with 1" diameter bowl and was made with diamond cutter. There are many trade offs. Many options. Trying to come to reasonable compromise.

[jabbr]

Hi j,

 

Try 'em out.

In my experience though, the smoother the bowl (i.e., the easier the ball can move), the more effective the isolation.

In other words, a high degree of smoothness is key.

 

Best regards,

Barry

Soundkeeper Recordings

http://www.soundkeeperrecordings.wordpress.com

Barry Diament Audio

 

Yes. My understanding is that when very high grade equipment is made there is one shop that does the machining and smooths to Emory 320-400 before being sent to an anodization and finishing shop that anodized and then places a mirror polish. Question is how much that second step costs-- reasonably

[jabbr]

Please don't take this the wrong way or too personally. But this approach is fairly typical of high end, and why I think it often puts cart before horse and while the resulting hardware is effective it often is not at all cost effective.

 

For instance, price going up rapidly with more and more polished or smooth surfaces. Yet no one is doing research or testing to figure out is there a point beyond which smoother makes no difference? Is there a point at which you get all your vibrations below and nothing else can help audibly? You know good enough so nothing better is actually better. Nope, not being done. Smoother is better, ad infinitum and in time so is the price.

 

One for instance, through my experimentation I know even surprisingly crude surfaces are indeed effective. Has anyone thought about the fact these are more or less like filters. Meaning you can cascade them for twice the effect. Is it better to triple price in order to smooth the finish picking up maybe 10% in performance (number I just guess at here) or would it be better to use two layers of cup and balls and shelves to double performance for double the price? Can relatively rough surfaces work as well as polished if given a dollop of silicon fluid? It might well be so. Would a less hard bearing on a rough surface metal cup have less resistance than a hard bearing? High pressure tires have less rolling resistance with less pressure on roughened surfaces.

 

At one time I had in mind prioritizing my vibration sensitive components. I would put bottom shelf on cup and ball, and it held my tube power amp, plus another cup and ball set holding my tube pre-amp, and it would hold another cup and ball set holding my TT. TT gets triple isolation (and needs the most), pre-amp gets double, and power amp gets single isolation. Something along those lines would likely get results possibly equal for the whole system of more extensive and expensive systems not put all together in priorities this way.

 

In the high end, it just doesn't work that way. It often results in stunning performance, but an equally stunning price, and then some. Too often available synergies are thrown out rather than taken advantage of because simplicity and extreme measures are easier to market and get people to believe in.

 

Excellent points. I agree although I am getting a set polished with Emery 320 which I will inspect. I am prepared to test this against a set of porcelain bowls. I am also prepared to polish and retest this set. I have a range of tungsten carbide (both craigballsales.com and taobao), silicon carbide (higher spec) and silicon nitride. To first listen, they are each pretty good. So in fact there is a large number of variables to test and frankly I often have a hard time telling the difference. Point being that good enough is good enough. Vibration isolation does make difference but I hope I'm able to tell the difference between chrome steel and tungsten carbide, but if I can't then certainly anything that is good enough for Barry Diament is good enough for me:) At $3-$4/ball for tungsten carbide from craigballsales.com, its something people should certainly try. At $35-40/ball from my friend's military spec connection, not so sure I'm going to try:)