Down the anti-vibration rabbit hole again...

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Smokedaddy
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Post by Smokedaddy »

enricosavazzi wrote: What you need next is a transducer that transforms vibration to an analog signal. The following module incorporates XYZ vibration transducers, and judging from the data sheet, would seem suitable (it measures between 1Hz-500Hz or 1Hz-100Hz for different models, which is plenty enough), but I have no information about price:
http://signalquest.com/download/Vibrati ... SQ-SVS.pdf
I tried filling out the stupid contact form for a price on 3 but without success, o'well.

-JW:

Joyful
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Post by Joyful »

Have you seen the 4-level pendulum setup used in the A-LIGO (Advanced Laser Interferometer Gravity wave Observatory) setup to suspend their mirrors from ??

They reduce vibration to a point where detection of 10 to the minus 23 orders of magnitude are possible ?

Some ideas for you there.

Oh - one thing - they are in the middle of a desert !

Beatsy
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Post by Beatsy »

Joyful wrote:Have you seen the 4-level pendulum setup used in the A-LIGO (Advanced Laser Interferometer Gravity wave Observatory) setup to suspend their mirrors from ??

They reduce vibration to a point where detection of 10 to the minus 23 orders of magnitude are possible ?

Some ideas for you there.

Oh - one thing - they are in the middle of a desert !
Dang - I hadn't thought of that! Guess I should scrap plans for an orbital macro platform then... :D

Joyful
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Post by Joyful »


ChrisR
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Post by ChrisR »

This is a snap of a free phone app. A 1 second exposure, phone strapped to the camera which sat on a bench.
Noise is more of an issue than sensitivity, which could have been set higher.
This is with slapping mirror.
There are many apps to choose from with different modes - linear accelleration, gyroscope, etc.
Image
Chris R

Smokedaddy
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Post by Smokedaddy »

ChrisR, if that was directed at me, thanks. I still want to figure out how to use my new oscilloscope toy for my rig vibration (or whatever). I have no skills in this area whatsoever. I also bought a function generator via eBay the other day. I suppose I need to find a forum to see how to accomplish this task.

-JW:

ChrisR
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Post by ChrisR »

It's worth looking at the apps, to see what their sensors can do. Their components are available for a couple of bucks.

If you get a lab power supply (which shows current and voltage), some breadboard, and a couple of multi-packs of components, you can set something up which shows vibration.

If you want to go from there to making, say, more than a certain amount of vibration throw a switch, you'd need some analog electronics knowledge, and you'll need to add controls - pots etc. And some digital components, probably. You'd get to know about voltage levels, resistances, amplifiers perhaps, data signals , comparators, timers, counters... I teach this stuff to (up to ) 16 year olds, (& beyond which you wouldn't need), so I can send you a course (and mark your exercises!). Actually we have a few 12-13 yr olds coping with the first part, if they're keen.

There are lots of kits of simple circuit kits (eg search for 555 AND 4017) on ebay which will quickly show you what's easy/possible at that level.
There are free circuit design packages (like Yenka) which would help at that stage too

At a certain point you'd probably be thinking that it would be better to be using a processor like an Arduino, or Raspberry Pi, to measure the vibration. Then you can use standard Arduino-compatible controls, displays and outputs for things like lights and relays.

You can use the modules anyway in non Arduino circuits. Some of them are particularly good. If you want a variable 10 second timed output which switches 2 amps, it'll cost you about $1.99!

If you want to make a system which has "take next shot in stack" as an input signal,
then waits for the rig to be still,
then sends "expose next frame" to an output
then checks to see if the flash fired
then either outputs "DONE" , or ALARM, or REPEAT EXPOSURE or counts the failures first,...

you can do it with an Arduino more simply than separate components. But by the time you'd learned how to use an Arduino you could have done it with standard elements of circuitry.

The early parts of analog self-education would still be very useful if not vital.

Then if you wanted to build a whole stacking system, you'd really need a processor. Otherwise it would be huge and complex. There's more & easier support for Arduinos on the web, than there is for "circuitry".

Good luck on your journey!
Chris R

Beatsy
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Post by Beatsy »

Follow-up: well, that's my rig sorted. The solution was a 600x600x35mm concrete slab sat on 9 Sorbothane hemispheres with 5 smaller hemispheres on top of that supporting the original 500x500x10mm steel plate. An optical rail is bolted to the plate with a WeMacro rail, camera and specimen stage attached to that (horizontal rig).

I had a (very) strenuous time "tuning" the base. Cutting a long story short - I spent ages (and no small amount of sweat) trying out different combinations of 1 or 2 concrete slabs with various sizes and numbers of Sorbothane feet under the base and between concrete and steel. Although the amount of vibration being "cured" was pretty small (only visible at 50x), none of the combinations seemed to reduce it. So I hit Google again but concluded I just hadn't found the right combination yet. Sigh!

So, I setup my android pad to record vibrations and get quantitative data on each change. I started with the setup I'd last tried so also had the live view running. Banged an adjacent table - nothing. Wheeled my chair around the floor - nothing. Stamped on the floor - nothing. Banged the table with the kit on, a small wobble (to be expected). Every one of these tests had caused a visible wobble just half an hour earlier but now it was working perfectly!? It appears that Sorbothane needs a short time to "settle" before it reaches maximum vibration-absorption. Possibly the high elastomer content? I dunno. But I don't care either - it's working and that's fine by me. I don't fancy another major work-out just to see if I can make it a few percent better :)

Irisoratoria
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Re: Down the anti-vibration rabbit hole again...

Post by Irisoratoria »

My street is not very busy but I live 150 meters from the train track, when the train passes vibrations are important. I found a good solution with the rail on two granite slabs of 12 kilos each (24 kilos in total). I put silicone for mirrors between the two slabs (it sticks hard and is anti-vibration). Underneath are hemispherical Sorbothane stickers. The equipment is screwed to a 3 cm thick oak sheet. Vibrations are not noticeable now (I took photos up to 20 magnification)
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MarkSturtevant
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Re: Down the anti-vibration rabbit hole again...

Post by MarkSturtevant »

This seems more like an Equipment discussion post.
I could have sworn that I saw a post somewhere here where someone used bungee cords to solve a vibration problem, but I can't find it. It might not have been a post about vibrations.
In my 'former life' I was in a research lab where people would do micro-injections of DNA into fruit fly eggs (long story). The cast iron platform on the table top was floated on a couple bicycle inner tubes. This to effectively suspend the weighty microscope and micro-injector thingy on a cushion of air. It would be a simple and inexpensive thing to try, at least.
Mark Sturtevant
Dept. of Still Waters

rjlittlefield
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Re: Down the anti-vibration rabbit hole again...

Post by rjlittlefield »

MarkSturtevant wrote:
Wed Feb 02, 2022 2:54 pm
This seems more like an Equipment discussion post.
I agree. It was also idle for over 4 years, until resurrected by Irisoratoria's post.

So with no further ado and no waiting, I have moved it to Equipment Discussions.
I could have sworn that I saw a post somewhere here where someone used bungee cords to solve a vibration problem, but I can't find it. It might not have been a post about vibrations.
At viewtopic.php?p=236581#p236581, Chris S. reports using that approach to suspend an illuminator, to prevent its fan vibrations from coupling into the rest of the photo system.

The platform-on-inner-tubes approach is a classic technique. It works best with lightly inflated tubes, just barely enough to support the platform.

--Rik

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Re: Down the anti-vibration rabbit hole again...

Post by Chris S. »

I could have sworn that I saw a post somewhere here where someone used bungee cords to solve a vibration problem, but I can't find it. It might not have been a post about vibrations.
I recall someone referring to such an approach in an offhand reference within a larger discusion. I don't recall detailed documentation of it. (This said, my recollection is sometimes as sharp as a soccer ball.)

rjlittlefield wrote:
Wed Feb 02, 2022 5:19 pm
At viewtopic.php?p=236581#p236581, Chris S. reports using that approach to suspend an illuminator, to prevent its fan vibrations from coupling into the rest of the photo system.
For clarity: My illuminators are suspended from braided nylon ropes, not bungees. My first stab was a rope suspending one illuminator. This worked well, so I hung a wooden shelf from four ropes and placed three illuminators on it. This has served me faithfully for years.

For vibration reduction, I'd avoid springy things like bungee cords, and look more at "stretch and slowly return" things like braided nylon rope. For vibration reduction, we want to remove energy from the mechanical system. "Bouncy" things like bungee cords retain energy. Stretchable, but slow to return, things like braided nylon rope dissipate energy. Dissipated energy is energy that isn't hanging around to bother us.

And as Rik said, in my use, the hanging shelf's purpose is to isolate the illuminators' vibration from the camera/subject stage. Consider how energy would have to travel, to get from my illuminators to my photo system: Vibration would have to go up the ropes, across floor joists, down cinder-block walls, across a concrete floor, up a slate pool table, then into my (somewhat massive) rig. That is many degrees of decoupling (aka, lots of attenuation).

But this is very different from suspending a photo system on a hanging platform. I think such platform could work for holding a photo system. The trial and error to make it work might be, um, amusing.
The platform-on-inner-tubes approach is a classic technique. It works best with lightly inflated tubes, just barely enough to support the platform.
Classic indeed. Also the dominant approach to vibration reduction for most optic/scientific instruments: Create a platform with mass; put this platform on something squishy; let the world vibrate below, while the platform floats serenely still.

I'd avoid bicycle inner tubes--too big, unless one builds something to contain them and runs them in serpentine-fashion within this container. There are smaller inner tubes intended for go karts and wheelbarrows, which I've used. Roller Blade inner tubes are even smaller, and look interesting. But NB: When small inner tubes are barely inflated, as they should be for this use, the valve stems stick out and can mechanically interfere with the intended use. Venture here only if you are interested in dealing with this issue.

--Chris S.

Beatsy
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Re: Down the anti-vibration rabbit hole again...

Post by Beatsy »

rjlittlefield wrote:
Wed Feb 02, 2022 5:19 pm
MarkSturtevant wrote:
Wed Feb 02, 2022 2:54 pm
This seems more like an Equipment discussion post.
I agree. It was also idle for over 4 years, until resurrected by Irisoratoria's post.
<snip>
--Rik
I was surprised by this thread reappearing nearly 5 years since I last commented on it! First, where did the time go? Second, I've changed just about everything about my anti-vibration approach since then. I moved from "lots of mass" to "lots of rigidity" instead. Most of my macro/micro/manipulator gear is now attached to Newport optical benches with the only soft insulation sitting between the bench tops and the sub-frame (and that's just passive hemispheric sorbothane bumpers). The only vibration this setup was initially susceptible to was traffic going over a speedbump on the nearby road (as before with the heavy bases). That was cured by adjusting the size and number of bumpers under the corners of the table tops.

In short, stable, rigid (and rather expensive) tables solved just about every problem I was getting with vibration and flexion (the last being where free-standing micro-manipulators would tilt relative to the sample on the microscope as I leaned on a normal table and flexed it a few microns). Now everything sits rock solid during use. I've run with this setup for over two years now and won't be changing it - I'll just continue with frequent re-arrangement of the stuff bolted on top, which this setup makes a lot more convenient too.

Adalbert
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Re: Down the anti-vibration rabbit hole again...

Post by Adalbert »

Hello everyone,

I have experimented too and found out that the heavy rails made of steel are problematic.
They resonate quickly and take a long time to settle down.

That's why I have built an ultra-light wooden rail.
The vibrations from outside have no influence on the rail.
In order to minimise the internal vibrations caused by the motor and the movement of the rail
I have isolated mechanically the camera and the object from the remaining part of the rail.
https://www.facebook.com/photo/?fbid=12 ... 0269581589
https://www.facebook.com/photo/?fbid=12 ... 0269581589

This is my personal observation and experience, not a general statement.

Best, ADi

MarkSturtevant
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Re: Down the anti-vibration rabbit hole again...

Post by MarkSturtevant »

:) You know, I never think to look at dates on these things. Well! A lot has changed over the years! Next time this is resurrected I wonder if we will be under rule by robot overlords or something.
Mark Sturtevant
Dept. of Still Waters

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