Vibration isolating rollerballs

[YashN]

As I understand, the question of design/measurements of bowls for group buy is open. In one of his posts in other thread Barry gave an idea of some measurements (not all) he used. I am sharing the design (everything is in mm) which I used for the bowls I have already for some time. Anyway, let's discuss.

 

[ATTACH=CONFIG]19531[/ATTACH]

 

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.

[YashN]

From a practical point of view however, the bowl keeps the ball bearing centered.

 

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).

[YashN]

Won't happen if there is a curve at the very end.

[YashN]

I would very strongly caution against this. Wait 'til you actually do it. I say, on the contrary, there is no benefit to having a flat surface. The ball *must* be in a curved bowl if you want to set up the resonance that will result in the isolation. On a flat surface, the ball meanders, and nothing else happens. Try it and see.

 

On the contrary, it seems you misunderstand why the isolation happens.

 

You should re-read John Swenson's thought experiment post on the other thread and do the thought experiment to see why.

 

A flatter surface is more optimal for isolation in the horizontal plane.

[YashN]

Additionally, there are a lot of fraudulent balls on the internet...just labeled as the higher grade/material. If the price seems better than it should be, it probably is. Just saying...

 

Good point.

[YashN]

In terms of understanding or misunderstanding, I can only offer what I've learned from experience and hope it is of use. I much prefer empirical data, i.e., direct experience, to theory.

 

There are the theories being expounded and there is the practical, real-world reality. Once you move on to the latter, understanding of why isolation happens and when (and when not) in actual use with audio and video gear will dawn.

 

Go ahead and try it yourself: you've gone half-way by removing the upper cup. Remove the cup below and the isolation is further improved.

 

Try it on smaller piece of equipment and set up some material it can 'roll' or 'fall' on to at extremes of motion, said material being of dimensions slightly smaller than the diameter of the balls.

 

If you read what John said, notice the mention of needing PERFECT leveling.

 

That is correct. Use a level surface, Or as close to level as is possible, in conjunction with the 'safety' devices I mention above.

 

If you've read my posts so far, you know I always suggest folks try things for themselves. Actually trying these things out will tell you more than I ever could. (Even in the post you quoted, I said "Try it and see.")

 

In reality, you oscillate between repeating for others to try things and discouraging others from trying anything that is different from your own current setup, at least that's what I've noticed.

 

No need to repeat to me to try things for myself, I think there's sufficient evidence I am already doing that (and not just for vibration isolation!)

 

Cheers.

[YashN]

You may have forgotten but while isolation may be new to you, I experimented with *all* of this well over a decade ago. That is how I arrived at what I decided to use. I'm at loss to figure out why you'd think I hadn't already been there and done that. No matter.

 

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

 

This is not true. Perhaps that is what you inferred but the evidence of my posts would not support such an assertion.

 

The last exchange where you keep speaking about your speakers where mine as different is what makes me say this.

 

Perhaps it is best if I just don't reply to your posts. In all honesty, the last few from you are feeling less than friendly.

 

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.

 

If someone not agreeing with you is what you call 'feeling less than friendly', then feel free to ignore what I told you, knowing that John Swenson said the same thing.

 

The CA forum has an 'Ignore' feature. Use it.

[YashN]

My, my, someone got out of the wrong side of the bed this morning, didn't they?

 

If someone wrote this to you, you would qualify it as <fill in the blank>?

 

1. Curvature of the bowl doesn't make the isolation. Curvature of the bowl makes for *practical* (as opposed to theoretical) isolation.

 

The first sentence is exactly what I said. Very different from the following, where in fact, you thought just the opposite:

 

Wait 'til you actually do it. I say, on the contrary, there is no benefit to having a flat surface. The ball *must* be in a curved bowl if you want to set up the resonance that will result in the isolation. On a flat surface, the ball meanders, and nothing else happens. Try it and see.

 

Good thing you changed your stance as if you go back the original thread, was trying to see if adding more damping would make the system better. Why? For two reasons: in some actual anti-shock arrangements there is damping added. Secondly, what do you think gravity and friction are doing to the pendulum-like motion of the ball?

 

Damping.

 

Initially, you wrote you didn't want any damping at all to maximise isolation. This was contradictory to using gravity (and the curved surface). Once you sort out the contradictions and get a better model for how things work and what should be optimised, you can design and build a better solution. There are pros and cons to each type of implementation, usually constrained by variable like cost and space.

 

2. I have no problem with disagreement. It is incivility that is the issue. Actually, it would seem *you* are the one with the problem regarding disagreement, evidenced by how quickly--and often--you've forgotten your manners. Again no matter. And given your previous posts, no surprise.

 

The only one showing difficulties in accepting disagreement is you.

 

I wish you happiness. And perhaps one day, if not knowledge, at least a modicum of maturity.

 

Don't you think maturity and civility also implies acknowledging where you went wrong in modeling the phenomenon, as well as recognizing that when people disagree with you and point the facts to you, they aren't being 'unfriendly' in any way? Maybe practising what you preach about civility and maturity is in order.

[YashN]

Give it a rest.

 

Is that you, prout? I'll add you to my ignore list with all the other trolls.

 

Take isolation to whatever degree you want and we'll all do the same.

 

Why, isn't pushing the boundaries of what this is exactly what we (proper contributors) are doing in the thread? I haven't seen you contribute anything.

[YashN]

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

 

In the spectrum of sub-optimal, you can move a little more towards optimal. For the horizontal plane, I already described how.

 

Maybe you missed it, but some people already veered off into a group buy...

 

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!

 

Same approach here. I also think there are improvements to vertical isolation to be made, and additionally to tilt control.

 

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.

 

There could be something to it, but it requires more analysis and data, equipment + material and a willingness to experiment and learn along the way rather than being stuck in an inaccurate model because 'been there done that', 'this may be new to you', 'I've already tried everything', etc...

 

I can devise part of the equipment and I have some equipment that can be useful, but getting materials is difficult for me.

[YashN]

The problem with where you are headed is that there is nothing to stop the sideways motion of the top vs the bottom surface. If you use a bowl with a flat bottom then the upper panel will slide sideways without resistance until it meets a curvature and then will start to ride up that curvature until gravity overcomes the sideways force being applied. If you stop applying a sideways force the platform will simply come to rest at the point where the flat bottom meets the beginning of the upward curvature. In a constant bowl, that is at the center of the bowl, but it is always the slope of the curved wall that determines how much resistance there is to any vibration in the horizontal plane.

 

No, the safety device is the curvature even with the flat surface bowl but at the end of the race, but you do need the surface on which the cup rests to be horizontal or else things will immediately slip and moreover, you would want the flatter bowl to be rather large and also strongly set on the platform supporting it. There is more info on this thread. You would probably get more from the thread by starting from the original post and reading through. We already established the motions in daily use aren't visible (not including handling the component) and that isolation in the horizontal plane has to be as free as possible, therefore the gentler the curvature, the better the isolation. Hence the thought of using a flat surface, which has its own set of design and implementation constraints.

 

In theory there is a way you could create an isolation platform that has virtually no resistance side to side (think about the magnetic levitation used in Maglev trains -- where electromagnets are used to create a virtually friction-less interface between two surfaces). But once again you have to do something to keep the top part from just continuing its sideward slide until it falls off.

 

There are ways to do that too, but we haven't discussed this in great detail yet, presumably there are very few implementations. I may have come across one mentioning it but I can't recall the name. If I do, I'll add it to the other thread.

 

So Barry has found what I believe is simply the best practical solution.

 

That's not true to me: it clearly isn't the best practical solution, neither for DIY nor among commercial implementations. It clearly is very good compared to having nothing, and even for daily use, so it's a good start for exploration, and I would say it is an intermediate solution for DIY. Then again, it all depends on what you understand as 'the best practical solution'.

 

Continue on the fallacy that the curve must be there to help with isolation, and soon enough you have people using and buying bowls with radically high curvatures, which actually end-up hampering the isolation.

 

The one interesting modification is the one suggested by Daudio, which is to figure out what the optimum ratio between bowl size and ball size is and how that affects the resonant frequency of the device. Although I believe a smaller ball will prove to be better from a resonant frequency perspective, too small a ball will create more movement friction between the ball and the surface of the tile sitting on it.

 

It's worthwhile to explore, but it is not the single interesting modification. Many more have been discussed, and more than just the horizontal - there are 6 degrees of freedom in which vibration can act and which we need to isolate against ideally.

[YashN]

Geez, you try and provid real life experience and results from your findings, you engage in a flurry of questions with him in the other thread, haven't pushed any agenda, etc..? A simple agree to disagree would have been sufficient from him. Good lord.

 

Yes, the ignore feature will come in handy

 

You and I have a VERY different perspective on the facts. Try harder not to distort them.

[YashN]

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

 

It isn't a large seismic event these are meant to isolate from, but the smaller everyday motions: vehicles, bridges and buildings flexing, lower earth seismic activity, roadworks, etc...

 

In practice, the ball would move very slightly at a time.

 

For the larger shock events, the last thing you will think about is SQ, you'd rather be running fast or hide somewhere safer or do whatever people that is recommended in these cases.

 

Check the Townshend PDF linked to in the original thread, I think it's called Earthquakes and your Hi-Fi or something like that.

[YashN]

Think of it as a long pendulum, those can swing at small amplitudes not easily visible, yet the period of oscillation is unchanged.

 

Indeed, it is a model of a pendulum.

 

It occurs to me you could make use of a flat surface and weighted ball bearings. They would need to be larger. If the bearing is weighted heavily to one side that side will end up being down. Align all 3 or 4 such bearings and small disturbances will still re-center themselves. Of course this would be a higher frequency of resonance due to the effectively shorter pendulum.

 

Another possibility is a hard hollow bearing with fluid in it. Fluid less than full would have some of the same effect if high viscosity. It would dampen as well as re-center for small movements. That might be tricky to optimize.

 

It could be interesting to try these two, probably not that easy to test different setups.

[YashN]

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?

 

The disadvantage here is that should the component/ball find themselves at the edges of the race, i.e. in contact with the edges, you would need to move them back near the centre (it doesn't have to be the exact centre).

[YashN]

You have done a lot of reading in many disparate and far flung areas of vibration isolation and conrol. Which is great, but my very strong feeling is that you have not yet fully integrated all that data in your head.

 

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.

 

This is the reason why you hadn't yet understood that the ball being centered or the ball being brought back to the center by gravity isn't necessary for proper isolation...

 

Had you stuck around in the thread and made the effort of reading properly not just the papers linked to but also the various posts by people who are actually interested of delving deeper in this subject, you probably would also have seen a post by John Swenson saying there could be merit in a mostly flat surface.

 

I'll take the feedback of a single John Swenson over a million of you nay-sayers and easy accusers any day.

 

That, and the primitive state of your home experimentation, make me regard your statements with less impact then from someone who has been involved a lot longer, and done much more direct experimentation.

 

The only thing primitive here are your understanding and accusations. I probably already made a lot more experiments and measures than you did.

 

I find your arrogance towards disagreements misplaced and counterproductive, and a poor approach towards unraveling the mysteries of this interesting area which confront us all.

 

Please chill out, and return to the search

 

Maybe you should spend more time and effort trying to understand what those of use providing alternate designs and better optimised ways of doing things are writing about and come to your own conclusions.

 

By your own admission, you have difficulty 'following me', but that doesn't mean what I write or do is without value, just that it's difficult for you to understand...

 

This requires effort, study, research, and not blindly following someone who has an inaccurate model of how the phenomenon works.

[YashN]

Yash: I'm going to agree with Daudio's suggestion that you take a bit more time to digest your own reading. There are some "laws of physics" involved here that we are unlikely to rewrite. The first of these is that once an object is in motion on a truly flat and super smooth surface, it will not stop unless there is something to resist it. If that is the lip at the end of the smooth part, then the only thing that really matters is what is the curvature of the lip.

 

Daudio had some difficulty in following the physics. It seems you do too. In a flat surface, there is still friction/sticktion.

 

Re-read what John Swenson and I said above, find the gedankenexperiment he proposed in the other thread, think it through and you will see why (maybe, maybe you will also need to test it as I also did).

[YashN]

Have you ever wondered why you are such an argumentative little bugger?

 

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?

[YashN]

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.

 

Indeed, jabbr, I agree. The other thread and discussions about the theory and implementation are better there. Didn't mean to derail your thread, but saw blatant misunderstandings that needed correction.

 

See you there.

[YashN]

I am not sure how to say this, but you are picking on the wrong man. Barry has been a very friendly and helpful poster here.

 

I do not agree with you either.

[YashN]

Wow, those bowls look great! If your source wants to charge $60 to $75 for a set of three based on the work already done, I bet he can sell 20+ sets in about a day. I'd definitely be one to buy multiple sets...

 

Would you be willing to ask?

 

John

 

The price is great.

[YashN]

YahN, due respect, your comments are disrespectful and in my opinion uncalled for.

 

Second useless post I see you post about me. On the ignore list you go as well.