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Current Posts => Collecting, Modding, Turning and Spin Science => Topic started by: Bill Wells on August 08, 2022, 01:07:49 PM

Title: Shop made gyroscope
Post by: Bill Wells on August 08, 2022, 01:07:49 PM
I just completed making this gyroscope in spite of unexpected challenges along the way. It's not easy, I found, making a precision instrument in what is essentially a woodworking shop. My first attempts failed mainly because tolerances and fits were not "tight" enough. In other words, sloppy won't work.

This one won't walk a tightrope.


https://youtu.be/RXxW0O25KEE
Title: Re: Shop made gyroscope
Post by: Jeremy McCreary on August 08, 2022, 03:14:36 PM
Beautiful in both design and execution, Bill! Please let me know when mine's ready.

Enough procrastination -- back to packing.
Title: Re: Shop made gyroscope
Post by: the Earl of Whirl on August 10, 2022, 03:48:44 PM
Very interesting!!!
Title: Re: Shop made gyroscope
Post by: Bill Wells on August 18, 2022, 10:20:49 PM
Very interesting!!!

Thank you. Interesting yes, and perplexing. Still trying to understand the physics.
Title: Re: Shop made gyroscope
Post by: Iacopo on August 19, 2022, 07:56:26 AM
Interesting yes, and perplexing. Still trying to understand the physics.

One of the simplest explanations is in the following video. 
At least, this is the video that made me understand the basic logicality of the gyroscopic motion:

https://www.youtube.com/watch?v=_g3KSAqJ7Hs
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 06, 2022, 12:28:42 AM
One of the simplest explanations is in the following video. 

Thanks Iacopo. Seems that bicycle wheels are favorites when demonstrating precession.
I have been studying the subject for some time now, using the classical methods of torque and rotational inertia. I may now understand the principle.
 
I also made an electric motor driven gyroscope. The 4000 RPM DC motor was between two flywheels. My intent was (still is) to use it as a gyroscopic compass. I had it spinning, suspended in my workshop. It started running smoothly but somehow the imbalance became resonate and quickly the gyroscope disintegrated. The motor was ruined as well as many of the items on my workbench. After buying a new motor I will continue the experiment. Of course learning from my mistakes.
It seems that a gyrocompass should easily maintain it's axis direction while Earth revolves around it.  However, experiments with my smaller gyroscope were not successful. I will post photos and results of my trials in the future. A few months.

I love your new tops, how do you achieve such a brilliant finish?

Alla Prossima, Bill
Title: Re: Shop made gyroscope
Post by: ta0 on September 06, 2022, 09:52:44 AM
It seems that a gyrocompass should easily maintain it's axis direction while Earth revolves around it. 
No, not easily.
First, we need to distinguish between a Gyrocompass (used in ships) and a Heading Indicator (used in aircraft). Both used gyroscopes, but the first one aligns with true north (slowly) while the second keeps pointing in a certain direction (for a while).
You are thinking about the second type. But they only can keep the direction for a while until friction makes them wander away and the error accumulates. On an small airplane you have to periodically realign it using a regular magnetic compass (on large planes the feedback is automatic). The reason they don't just use the later, is that when the plane is rotating and accelerating the magnetic compass gives wrong indications.
I believe Foucault who invented (or made popular) the gyroscope tried to used it to measure the rotation of the Earth. If I recall correctly, he was only partially successful and was more successful with his giant pendulum.
Title: Re: Shop made gyroscope
Post by: Iacopo on September 07, 2022, 03:47:24 AM

It seems that a gyrocompass should easily maintain it's axis direction while Earth revolves around it.  However, experiments with my smaller gyroscope were not successful. I will post photos and results of my trials in the future. A few months.

The degree of precision needed in a gyroscope for to detect the rotation of Earth is high and very difficult to achieve with our simple home made devices. I couldn't do this with my home made gyroscope. Not even with the "super precision gyroscope" sold by www.gyroscope.com. 



I love your new tops, how do you achieve such a brilliant finish?

Thank you! I sand the brass up to grit 7000, then I polish it by hand with diamond paste grit 200,000, and cotton wool.  I sand the wood up to grit 3000 then I treat it with Shellawax.  But the main ingredients are time and patience.
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 16, 2022, 12:06:52 PM
I believe Foucault who invented (or made popular) the gyroscope tried to used it to measure the rotation of the Earth. If I recall correctly, he was only partially successful and was more successful with his giant pendulum.

Yes, Foucault is credited with inventing and naming the gyroscope. He initially used the pendulum, then a year later the gyroscope. It was hand cranked to 12,000 RPM and ran for about 10 minutes. See attached photo.

I am stubbornly continuing my experiment and agree that it is not easy. I will power the gyroscope with a continuously running DC motor and probably float the entire thing in water.



(https://i.ibb.co/KNDTjD4/1-s2-0-S1631070517301019-gr002-lrg.jpg) (https://ibb.co/KNDTjD4)
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 16, 2022, 12:17:49 PM
The degree of precision needed in a gyroscope for to detect the rotation of Earth is high and very difficult to achieve with our simple home made devices. I couldn't do this with my home made gyroscope. Not even with the "super precision gyroscope" sold by www.gyroscope.com. 

I also have the "super precision gyroscope" and it is certainly an excellent device. I used the included drive motor in an unsuccessful attempt to detect rotation of Earth. So will continue, using larger home made devices.
Title: Re: Shop made gyroscope
Post by: ta0 on September 17, 2022, 02:06:46 PM
Nice drawings of the Foucault gyroscope. I don't recall seeing them before. I have a book called Pendulum about his life but it doesn't have them. I re-read the part about the gyro and it seems that he did detect the rotation by looking at the gryo movement with a microscope. This makes sense as it did not have a motor and he had to detect it over a short time.

I looked on the internet for an experiment showing the rotation of the earth using a gyroscope. You would think this would be an experiment that would be done at every educational physics lab, but it's not. That tells me that it's very difficult to do.

I found a couple of videos on youtube that claim to have done it. The most interesting one is this (you only have to watch the first 15 minutes). He took a lot of precautions doing the experiment and provides the complete experimental results. Unfortunately, I think he fooled himself:

https://www.youtube.com/watch?v=xNYW8JWMVOY

Title: Re: Shop made gyroscope
Post by: Bill Wells on September 18, 2022, 12:34:42 AM
Thanks Jorge, this is useful. I'm not quite at the millionth of an inch precision.

I am also considering latitude in my work. I'm at almost 47 degrees here. This is an important consideration.

There are several (three?) YouTube videos where the experimenter floats his gyroscope in a "boat" to reduce friction. None of them consider latitude. I'm skeptical of their method. Seems it would be feasible at North Pole only. Its notable that none of these were successful. 

Question for you: would a DC motor generate a magnetic field that would tend to align with the earth magnetic field? I'm using 6V and 12V motors to power the flywheels. I don't want the motor to induce error. Interesting that the gyro compass in your video is air driven.
Title: Re: Shop made gyroscope
Post by: ta0 on September 18, 2022, 12:59:23 AM
You are correct, if you measure the rotation in a horizontal plane, you have to apply the same correction factor as for the Foucault pendulum: multiply by the sine of the latitude. So it would turn 15 degrees per hour at the poles, but only half that at 30 degrees latitude and would not rotate at the equator. The guy on the youtube video I posted had the correct idea: place the gyro on a plane that remains parallel to the equator and align the gyro axis perpendicular to the direction to the North Star. Unfortunately, I believe he doesn't align it correctly (although, because he is close to 45 degree latitude, this error is not too big).

No, I don't think a DC motor would align with the Earth magnetic field. But I'm not too sure why the heading indicator and several other instruments on airplanes typically work with "vacuum".

Edit: A small, cheap, DC motor with just two poles would align with the Earth magnetic field. Motors with a large number of magnets should not do that.
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 18, 2022, 12:52:31 PM
...place the gyro on a plane that remains parallel to the equator and align the gyro axis perpendicular to the direction to the North Star.

Yes, exactly what I will do after my new DC drive motor arrives. I did preliminary trial in this way using the "Super precision gyroscope". Now I am turning larger flywheels on lathe and will have more powerful 12V double shaft motor. The inclined plane will be set at 43 degrees since I am at 47 latitude. And will have a more precise alignment with Polaris. Also better anti-friction bearings. If this setup works there will be photos and video. If not successful, will find some other way to spend my time.   :(
Title: Re: Shop made gyroscope
Post by: ta0 on September 18, 2022, 01:24:32 PM
The inclined plane will be set at 43 degrees since I am at 47 latitude.
Correct. But note that the guy in the video (starting around 10:00) aligns it wrong. If you slope the plane so it goes up towards the north by 90 minus the latitude, the plane would not point to the North Star, and rotating it 180 degrees will not make it perpendicular (unless you are at 45 degree latitude). The way to do it is to slope the plane by 90 minus the latitude but going up towards the south: that will make the plane perpendicular to the direction of the North Star.
Title: Re: Shop made gyroscope
Post by: Iacopo on September 19, 2022, 03:13:37 PM
Yes, exactly what I will do after my new DC drive motor arrives. I did preliminary trial in this way using the "Super precision gyroscope". Now I am turning larger flywheels on lathe and will have more powerful 12V double shaft motor. The inclined plane will be set at 43 degrees since I am at 47 latitude. And will have a more precise alignment with Polaris. Also better anti-friction bearings.

I saw a couple of videos with the flywheel kept in motion with electric motors, with the set up floating in water, and it seems to me that the magnets of the motor do act like a compass. Maybe a solution could be to use two equal electric motors mounted in opposite positions, trying to neutralize the magnetic field.  I would enclose the spinning flywheel, and maybe even the motor(s), in a cover, for to avoid thrusts due to the air moved by the flywheel.  A second larger cover could be put around the whole floating gyro, for to avoid the possible influence of air currents in the surrounding environment.  There could be currents in the water too, caused by temperature differences, which could be better to try to avoid. The most difficult part is to have a gyro that spins with a stable orientation, without random movements, sufficient for to detect the Earth rotation which is only 1 degree every 4 minutes, twice slower than the rotation of an hour hand in a clock.   
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 19, 2022, 08:11:47 PM
... it seems to me that the magnets of the motor do act like a compass.

I also wondered about the magnetic field of the motors.  I asked Jorge, he is an electrical engineer. He now agrees that a cheap DC motor with two magnets (exactly describing my motor) would act as a compass. Not sure what I could do to compensate.

I also watched the YouTube videos where the experimenters had their motor and flywheel in a small "boat" floating in water.  Another video showed the motor and flywheel in a glass jar, suspended from above. None of these experiments were successful. None addressed the issue of alignment regarding latitude.

I will take all of your (and Jorge's) suggestions into consideration. I will also continue experimenting with the "Super Precision" gyroscope.
Title: Re: Shop made gyroscope
Post by: Iacopo on September 22, 2022, 04:04:12 AM
DC motor with two magnets (exactly describing my motor) would act as a compass. Not sure what I could do to compensate.

I thought to it in these days.  One possibility could be to make the flywheel to spin by inertia, without motor.
So there would be no problems related to the magnets.
There should be no need for a very long spin duration, after all; even after just 1 minute spinning, Earth rotated by 0.25 degrees, which is an angle easy to detect, using a laser pen and a mirror on the small floating boat, like in the YouTube videos we saw.

The problem of not having a motor is that the deceleration of the flywheel would cause a torque on the small boat;
if the plane of the flywheel is set at 43 degrees, a component of this torque would make the boat to rotate on the water and the stable orientation would be rapidly lost.

This problem can be overcome by setting the rotation axis of the flywheel exactly horizontal;
in this way, the torque from the decelerating flywheel would have no effect on the orientation of the small boat, which would remain stable.
The construction would be not too complicated, because it's a flywheel with two bearings, mounted on the small boat, no gimbals needed.
The horizontality of the rotation axis of the flywheel can be fine tuned by moving some weight in the boat from stern to bow or from bow to stern.

I believe in fact that it is not necessary the plane of the flywheel to be set at 43 degrees.
The Foucault pendulum works even at the intermediate latitudes, even if its plane of oscillation is always vertical; in the same way, the spinning flywheel should be able to follow the rotation of Earth, at the intermediate latitudes, even if the plane of its flywheel is vertical.

As for the problem of the currents, maybe it could be better to use oil instead of water;
water evaporates and this makes its surface to be colder, this certainly causes some currents in the water, with the colder water moving downwards.
The currents can move the small boat and hamper its stable orientation.
We want the liquid to be as steady as possible, so it could be better to use a liquid which does not evaporate, and that has the same temperature of the surrounding environment; also, with a sufficiently steady liquid, it would be not necessary anymore to use a device to maintain the small boat at the center of the pool.     
Title: Re: Shop made gyroscope
Post by: ta0 on September 22, 2022, 10:47:47 AM
Measuring the rotation of an inertial flywheel over a short time/angle is how Foucault did it. Not spectacular but probably the best approach.

If you start the gyro horizontal, it will not be anymore after a while, moving in a plane at [90° - latitude] from the horizontal.
If you constrain it to stay horizontal, you have to apply a torque, and this will make the flywheel precess. What you get is a gyrocompass that will align after a while with the north pole (with the help of friction).
If it's not constrained, the angle measured in the horizontal plane will be the rotation of the earth x sin (latitude), as per the Foucault pendulum (so about 70% for 43 degree latitude).
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 22, 2022, 12:17:20 PM
Jorge and Iacopo, thanks for your useful input.
I have several schemes planned for gyro compass experiments.

Presently using the Super Precision gyroscope. Learned something interesting yesterday. I was using the gyro in a configuration suggested in the operating manual. It would precess for a few minutes with the gyroscope getting lower and lower. I wondered why it would not precess for longer time, since spin of the flywheel was still very fast (I can now spin the flywheel up to 15,000 RPM). I suspected friction at the mounting, indicated with red arrow. So I mounting it upside down, suspended with a bearing ball between two magnets. This arrangement has lower friction. Result was much longer precession.
(https://i.ibb.co/hfkJkBc/gyro-3.jpg) (https://ibb.co/hfkJkBc)

(https://i.ibb.co/C7vC2yV/DSCN3688.jpg) (https://ibb.co/C7vC2yV)

(https://i.ibb.co/n02rHch/DSCN3690.jpg) (https://ibb.co/n02rHch)

flag for diego garcia emojis (https://emoticoncentral.com/category/flag-for-diego-garcia)
Title: Re: Shop made gyroscope
Post by: Iacopo on September 22, 2022, 02:48:16 PM
If you start the gyro horizontal, it will not be anymore after a while, moving in a plane at [90° - latitude] from the horizontal.
If you constrain it to stay horizontal, you have to apply a torque, and this will make the flywheel precess. What you get is a gyrocompass that will align after a while with the north pole (with the help of friction).
If it's not constrained, the angle measured in the horizontal plane will be the rotation of the earth x sin (latitude), as per the Foucault pendulum (so about 70% for 43 degree latitude).

You seem correct... The simple flywheel with its axis fixed horizontally and without gimbals on the small boat, seems more like a gyrocompass, unable to detect the rotation of Earth. So at least one gimbal should be added..
Title: Re: Shop made gyroscope
Post by: Iacopo on September 22, 2022, 02:51:58 PM
I suspected friction at the mounting, indicated with red arrow...

I can confirm it, I could see the same in my gyroscope, I even made a video about this effect, (the first of the three experiments explained here, "Effect of the friction of the bearings of the vertical axis in a gyroscope"):

https://youtu.be/s-wt6m7KDFo
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 22, 2022, 03:22:22 PM

(1)   One possibility could be to make the flywheel to spin by inertia, without motor.

(2) ... problem can be overcome by setting the rotation axis of the flywheel exactly horizontal;

(3)  .. it is not necessary the plane of the flywheel to be set at 43 degrees.


Iacopo, I noticed that you sent new reply with videos. Have not yet reviewed the videos.

Regarding comments above:
(1) I am now experimenting with our Super Precision gyro. Now have TWO of them! I can spin them to over 15,000 RPM by increasing voltage. That should give enough spin time.
(2) and (3) Setting angle to 43 degrees increases complexity. My experiments will be with axis horizontal.

Not sure what you meant in your comment: "The simple flywheel with its axis fixed horizontally and without gimbals on the small boat, seems more like a gyrocompass, unable to detect the rotation of Earth. So at least one gimbal should be added..".  Why would a flywheel with its axis fixed horizontally in a small boat not detect rotation of Earth?
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 22, 2022, 03:32:31 PM

I can confirm it, I could see the same in my gyroscope, I even made a video about this effect...


YOU MADE THIS GYROSCOPE?
Title: Re: Shop made gyroscope
Post by: ortwin on September 22, 2022, 03:47:38 PM
"Why would a flywheel with its axis fixed horizontally in a small boat not detect rotation of Earth?"


I don't think that he really meant that it can not detect rotation, is would act as a north seeking gyro compass and the rotation of the earth is of course the most important thing to make this possible. But with a gyro compass you can not detect directly at what speed the earth is rotating, it just points north.
With Foucault's pendulum you can calculate the rotational speed of the earth directly also with a gyroscope that is free, at least in part, to  keep the orientation of its axis stable in space. In the gyro compass this axis is aligning as well as possible in parallel to the axis of the earth.



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Title: Re: Shop made gyroscope
Post by: ortwin on September 22, 2022, 03:59:51 PM

I can confirm it, I could see the same in my gyroscope, I even made a video about this effect...


YOU MADE THIS GYROSCOPE?


I don't think Iacopo made himself the so called "Super Precission gyroscope" that is also visible in the video, but the shiny one that he starts with a string I am pretty sure he made all by himself. Really impressive indeed!
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 23, 2022, 12:20:04 PM
Really impressive indeed!

 I thought the gyroscope Iacopo was using in his demonstrations was a commercially made one similar to the one you borrowed from a university. Then it dawned on me that he actually made it!

Welcome back, Ortwin.  Among my recent wacky experiments was (accidentally) an example of eddy current torque. I used a Styrofoam boat  to float the spinning Super Precision gyroscopes, with a magnet in the pan to keep the boat centered. Made the boat rotate due to Eddie Current! Reversed spin of gyroscopes and boat rotated in opposite direction.
Title: Re: Shop made gyroscope
Post by: Iacopo on September 23, 2022, 02:23:02 PM
Why would a flywheel with its axis fixed horizontally in a small boat not detect rotation of Earth?

Because it would work like a gyro compass, maintaining its orientation relatively to Earth, like a compass, so it couldn't show that Earth rotates.

The reason, to use the words of Jorge, is that, with a flywheel having its axis fixed horizontally on a small boat,
If you start the gyro horizontal, it will not be anymore after a while, moving in a plane at [90° - latitude] from the horizontal.
If you constrain it to stay horizontal, you have to apply a torque, and this will make the flywheel precess. What you get is a gyrocompass that will align after a while with the north pole (with the help of friction).
Practically, if our small boat has its flywheel axis horizontal, and oriented east-west, as Earth rotates a bit, the axis of the flywheel cannot maintain its orientation relatively to the stars because it is constrained to follow the rotation of Earth; the rotation of Earth would cause a torque on the flywheel axis in the direction to make the east side of the axis to sink down and the west side to rise up.  Because of the gyroscopic effect, the movement happens with a 90 degrees delay, this makes the flywheel and the boat to rotate on the plane of the water.  The speed of the rotation of the boat would be the same of the rotation of Earth, so, on Earth, the boat would appear to be steady.

Anyway...

I think that this also depends on the direction of spinning of the flywheel;

if the flywheel axis is horizontal, and oriented east-west, and the flywheel spins with its upper part moving towards south, the gyroscope will rotate in sync with Earth, practically maintaining a stable orientation relatively to Earth.

But, in the same situation, if the flywheel spins in the opposite direction, (its upper part moving towards north), this should make the gyroscope to behave differently. We will see the gyroscope, and the small boat with it, to rotate clockwise on the plane of the water, (at a speed twice that of Earth, i.e. 0.5 degrees per minute).

If my reasoning is correct, the experiment could still be interesting.
The logicality is a bit more complicated than that of a gyroscope maintaining its orientation relatively to the stars, but it still shows, using a flywheel, that Earth rotates.  On the plus side, to make a boat with a flywheel fixed horizontally is relatively simple, there are not gimbals, it is easier to make it work precisely, without random movements. And the speed to detect is doubled, so it is easier to perceive it. 

     

Title: Re: Shop made gyroscope
Post by: Iacopo on September 23, 2022, 03:08:16 PM
YOU MADE THIS GYROSCOPE?

Yes I did !   ;)

(https://i.imgur.com/sEuwybi.jpg)

(https://i.imgur.com/Sq1SPRs.jpg)

But looking at the your I thought to make another one, with more wood and less metal.  Maybe one day...
Title: Re: Shop made gyroscope
Post by: ortwin on September 23, 2022, 03:51:56 PM
...
Welcome back, Ortwin. 
Thank you Bill, but I was never gone! It is true, my posts lately were mainly in the other section of the forum, but I followed this one at least.
The season with worse weather is coming up so I guess I will turn more to endurance tops again for the next few month. I still have goals there that I did not reach yet and some clear ideas how to move forward there. The main improvement I am hoping for will come from an idea you Bill brought here: a balancing method with a vibration app. We will see if it works for me over the course of the next few month.


....Among my recent wacky experiments was (accidentally) an example of eddy current torque. I used a Styrofoam boat  to float the spinning Super Precision gyroscopes, with a magnet in the pan to keep the boat centered. Made the boat rotate due to Eddie Current! Reversed spin of gyroscopes and boat rotated in opposite direction.

Sounds  like a fun effect you observed, but I don't quite get it:
Maybe a little rough sketch would help me understand your setup. My first impulse was to say " that is not eddy currents, it is just the conservation of angular momentum!" But then I realized that because of the opposite spin directions it can't be that.





Title: Re: Shop made gyroscope
Post by: Iacopo on September 25, 2022, 04:15:07 AM
I found the patent for an air gyroscope, (not made like the Kruger fountains), I don't know if this could be stable enough to maintain its orientation sufficiently to show the rotation of Earth, but the inventor says:

"Another object of my invention is to provide a gyroscope which may act as a true space fixed reference and in which precessional errors due to friction are greatly minimized".

This is the patent. There are two drawings also:

https://patents.google.com/patent/US2729106


If someone is interested, I found an air gyroscope for sale, ($ 450), Kruger fountains style:

https://www.pureunobtanium.com/product-page/air-gyroscope


It is not frictionless anyway; from a video, (of an air gyroscope like the one in the video below), I could calculate that it loses 5 RPM in 18 seconds, from 140 to 135 RPM.  It's a spin decay similar to that of my tops, in that range of speeds.
And I have no idea at all if during the precession it sinks down like normal gyroscopes, or it rises like tops, or it stays stable.
The nutation seems maintained quite longer than in gyroscopes with normal bearings.

An air gyroscope in action:

https://www.youtube.com/watch?v=XyLC_1KW1-A
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 25, 2022, 01:18:21 PM
If someone is interested, I found an air gyroscope for sale, ($ 450), Kruger fountains style:

Interested, yes, but not enough to spend $450.

My interest is in the experimenting. I am behind in reading and viewing all the recent replies on this topic. Presently learning from failed trials - that is how we progress.
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 25, 2022, 02:07:49 PM
...it seems to me that the magnets of the motor do act like a compass. Maybe a solution could be to use two equal electric motors mounted in opposite positions, trying to neutralize the magnetic field.
Jorge had the same concern. I confirmed this by suspending a large two magnet 12V motor. It definitely aligned with Earth magnetic field  :-[ .

I will try the two electric motor scheme, with two Super Precision gyros. Interesting that the gyros connected together completely cancel each other, no gyroscope effect. This can be remedied by changing polarity of battery connection. Then gyroscope effect is doubled.
 
(https://i.ibb.co/bbnPQZZ/double-gyro.jpg) (https://ibb.co/bbnPQZZ)
Title: Re: Shop made gyroscope
Post by: ortwin on September 25, 2022, 02:47:13 PM
...


If someone is interested, I found an air gyroscope for sale, ($ 450), Kruger fountains style:

...
We talked of possibilities making one here (http://www.ta0.com/forum/index.php/topic,6618.msg74697.html#msg74697) for showing the "intermediate axis theorem", "Kovalevskaya top" or "show the T handle effect with clarity". Did you continue with anything in that project? I must admit I have not.
You said you calculated the braking of that top is in the same range as your tops in some corresponding speed range. That would be just so great to have a top with that low a friction and at the same time the freedom of movement that a ball gives plus the possibility of choosing the different relative moments of inertia by moving weights inside the ball.
Title: Re: Shop made gyroscope
Post by: Iacopo on September 25, 2022, 03:52:34 PM
Interesting that the gyros connected together completely cancel each other, no gyroscope effect. 
 
(https://i.ibb.co/bbnPQZZ/double-gyro.jpg) (https://ibb.co/bbnPQZZ)


When you tilt the axis with the two gyros attached and spinning in opposite directions, do you feel a resistance to tilting ?  Or there is no resistance, as if the flywheels were not spinning ?  I am not sure about it.

Did you continue with anything in that project?

No I didn't, mainly for lack of time.  I keep it as a project in the drawer. 
I thought to some details, how I could make them. 
I observed carefully the video and it seems that there is no tendency of the air gyro to rise/fall while precessing. I like this fact.
Probably one day I will make it.  Maybe with the T handle effect too. 
I would buy the one I found, but $ 450 is too much.   
Title: Re: Shop made gyroscope
Post by: ortwin on September 25, 2022, 05:59:10 PM
...
When you tilt the axis with the two gyros attached and spinning in opposite directions, do you feel a resistance to tilting ?  Or there is no resistance, as if the flywheels were not spinning ?  ...
My answer, although you did not ask me, is, there is no resistance, it is as if the flywheels were not spinning!
At least if you tilt it around the center of the connection between the two gyros and the gyros are at the same speed. Bill will tell us first hand what he observes with his gyroscopes, I had the chance to feel it in experiments designed directly for that purpose in science centers similar to this experiment here (https://www.technorama.ch/de/exponate/doppelkreisel) or this one (https://www.technorama.ch/en/exhibits/rotating_chair_with_electric_double_gyroscope).
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 25, 2022, 11:51:56 PM
When you tilt the axis with the two gyros attached and spinning in opposite directions, do you feel a resistance to tilting ?  Or there is no resistance, as if the flywheels were not spinning ?  ...

There is no resistance, as if the flywheels were not spinning.
Title: Re: Shop made gyroscope
Post by: ortwin on September 26, 2022, 06:20:57 AM
@Bill: if you pick up the connected gyros (spinning in opposite directions) with a string, does it matter where you have the string? Does it matter if it is in the red or in the blue (center) position?

(https://i.ibb.co/ZLWtzM6/double-gyro.jpg) (https://ibb.co/ZLWtzM6)

 
Title: Re: Shop made gyroscope
Post by: Iacopo on September 26, 2022, 07:00:37 AM
My answer, although you did not ask me, is, there is no resistance, it is as if the flywheels were not spinning!
At least if you tilt it around the center of the connection between the two gyros and the gyros are at the same speed. Bill will tell us first hand what he observes with his gyroscopes, I had the chance to feel it in experiments designed directly for that purpose in science centers similar to this experiment here (https://www.technorama.ch/de/exponate/doppelkreisel) or this one (https://www.technorama.ch/en/exhibits/rotating_chair_with_electric_double_gyroscope).

There is no resistance, as if the flywheels were not spinning.

Thank you. As for the position of the string, I suppose there is no difference, there should be no gyroscopic motion in any case, but Bill can see it with his eyes.
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 26, 2022, 12:44:52 PM
@Bill: if you pick up the connected gyros (spinning in opposite directions) with a string, does it matter where you have the string? Does it matter if it is in the red or in the blue (center) position?
I can check this today, but pretty sure blue/red are the same - as if gyros not spinning. Seems they cancel each other out.
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 27, 2022, 11:42:45 AM
@Bill: if you pick up the connected gyros (spinning in opposite directions) with a string, does it matter where you have the string? Does it matter if it is in the red or in the blue (center) position?

(https://i.ibb.co/ZLWtzM6/double-gyro.jpg) (https://ibb.co/ZLWtzM6)
Sorry, took me a while to find blue string  ;D
With the gyros spinning opposite, it is like they are NOT spinning. No gyroscopic effect.

My current experiment with earth rotation is much a challenge of making/assembling/handling components. Then floating them in a boat. Several times the boat capsized. Dealing with eddy current (again). Dealing with Earth magnetic field (it does affect alignment of even small DC motors).
Title: Re: Shop made gyroscope
Post by: Bill Wells on September 27, 2022, 11:57:07 AM
I found the patent for an air gyroscope...

You know we will make one of these.  Seems that just a decent fan underneath would suspend a sphere.
Title: Re: Shop made gyroscope
Post by: ta0 on September 27, 2022, 01:01:46 PM
Practically, if our small boat has its flywheel axis horizontal, and oriented east-west, as Earth rotates a bit, the axis of the flywheel cannot maintain its orientation relatively to the stars because it is constrained to follow the rotation of Earth; the rotation of Earth would cause a torque on the flywheel axis in the direction to make the east side of the axis to sink down and the west side to rise up.  Because of the gyroscopic effect, the movement happens with a 90 degrees delay, this makes the flywheel and the boat to rotate on the plane of the water.  The speed of the rotation of the boat would be the same of the rotation of Earth, so, on Earth, the boat would appear to be steady.

I think that this also depends on the direction of spinning of the flywheel;

if the flywheel axis is horizontal, and oriented east-west, and the flywheel spins with its upper part moving towards south, the gyroscope will rotate in sync with Earth, practically maintaining a stable orientation relatively to Earth.

But, in the same situation, if the flywheel spins in the opposite direction, (its upper part moving towards north), this should make the gyroscope to behave differently. We will see the gyroscope, and the small boat with it, to rotate clockwise on the plane of the water, (at a speed twice that of Earth, i.e. 0.5 degrees per minute).
I don't know if I follow your reasoning.
I think the only difference regarding the direction of the rotation of the gyro is that in one case one end of the gyro axis ends up pointing north and in the other case the opposite side.
If there is no gimbal to let the gyro rotate with respect to the boat, it will drag the boat with it.
If it's free to rotate in the horizontal direction, it will rotate with respect to the boat (stationary with respect to the earth) but the rate of rotation will depend on the spin.
In a commercial gyrocompass, it is fully gimballed, but it's maintained horizontally with weights (like a balanced arm scale).
Title: Re: Shop made gyroscope
Post by: Iacopo on September 27, 2022, 04:12:10 PM
I don't know if I follow your reasoning.
I think the only difference regarding the direction of the rotation of the gyro is that in one case one end of the gyro axis ends up pointing north and in the other case the opposite side.
If there is no gimbal to let the gyro rotate with respect to the boat, it will drag the boat with it.
If it's free to rotate in the horizontal direction, it will rotate with respect to the boat (stationary with respect to the earth) but the rate of rotation will depend on the spin.
In a commercial gyrocompass, it is fully gimballed, but it's maintained horizontally with weights (like a balanced arm scale).

You are right, Ta0, I was misunderstanding how the gyro compass works.
I found a better article about it and now I understand it a bit better;
the gyro compass points north, not because it precesses at the same speed of the rotation of Earth, but because it stops precessing when it points north.

I try again.
The small boat with the flywheel fixed horizontally in it, is a simplest kind of gyro compass.
It works well onlybest at the equator.
In the drawing below, the small boat is at the equator, we see it from North Pole.
The flywheel spins, with its axis oriented east-west, (A), and it tries to maintain its orientation, but Earth rotates and in position B a torque from the small boat wanting to align itself to the sea makes the flywheel to precess, so the boat rotates on the plane of the water.
The boat rotates until the position C, then it stops rotating, and the flywheel remains with its axis oriented north-south.
The reason that the precession stops at this point is that now the flywheel axis is exactly parallel to the rotation axis of Earth, and, from here, the rotation of Earth does not change the situation of parallelism, so there is no more torque, and no more precession.

This works best at the equator because at the other latitudes, especially near the poles, the axis of this flywheel, horizontal, would never be parallel to that of Earth, and the flywheel would tend to continue to precess, the leverage for making the flywheel to precess becomes progressively less efficient, until, at the North Pole, the gyro compass doesn't follow the rotation of Earth anymore.     

(https://i.imgur.com/SARayAa.jpg)

Still the experiment with a small boat and a simple horizontal flywheel without gimbals maybe could be worth.
Depending on the direction of spinning and the orientation of the flywheel, before to point north, a clockwise or a counterclockwise rotation of the boat on the water could be seen, showing that Earth rotates.
Title: Re: Shop made gyroscope
Post by: Iacopo on September 27, 2022, 04:36:20 PM
You know we will make one of these.  Seems that just a decent fan underneath would suspend a sphere.

I started looking for the materials for making the mine. Even if I don't know yet when I will make it...
Title: Re: Shop made gyroscope
Post by: Bill Wells on October 01, 2022, 01:59:51 PM
In the drawing below, the small boat is at the equator, we see it from North Pole.
Iacopo, your drawings always help.

In the real world, experiments are difficult. Attached are photos of my attempts with floating the gyro in a small boat. As a convenience, I float the boat in the vacuum container used previously in my spin duration trials. Trials can be conducted in partial vacuum or in air.

(1)   It takes a long time for water to stop circular motion. It must be completely still before any gyro effect can be measured. Continuing water movement is always a problem.
(2)  Even with the small motor that comes with the Precision Gyroscope, the motor magnets do align with Earth's magnetic field. I may have solved that by shielding the motor with a steel cylinder.
(3)  I place a laser pointer on top of the boat in hopes of measuring angular motion. In last test, the pointer oscillated back and forth through 30 degrees for over an hour.
(4)  The middle photo, with gyro axis vertical, the Styrofoam block rotates in direction of the flywheel. This is simply due to friction. Rotation is slower when in partial vacuum.
(5)  In all cases, the boat is prevented from hitting wall of chamber by a pin attached to bottom of chamber, which extends up into hole in a Styrofoam block. This works well.
(6)  Gyro motor is driven by battery pack.

All this is very time consuming. May not continue this exercise in frustration. Unless someone has better suggestions.




(https://i.ibb.co/dGrGpkq/002.jpg) (https://ibb.co/dGrGpkq)

(https://i.ibb.co/7Sm9YQh/001.jpg) (https://ibb.co/7Sm9YQh)

(https://i.ibb.co/VHF1nTN/003.jpg) (https://ibb.co/VHF1nTN)






Title: Re: Shop made gyroscope
Post by: Iacopo on October 02, 2022, 04:32:14 AM
It takes a long time for water to stop circular motion. It must be completely still before any gyro effect can be measured. Continuing water movement is always a problem.

I think that it is difficult to have the water really still.
The problem is not only that water moves by inertia, (in which case we could simply wait until it stops moving), it moves continuously in any case because of differences of temperature.
You can put a drop of ink or something in the water to see its movements.
You can use mica, but mica tends to sink so it works well only if the liquid doesn't move too slowly, otherwise it settles on the bottom.
In the photo below, there is alcohol mixed with mica.
If you hold a glass in your hand, with alcohol and mica in it, you will see that the alcohol is not still but it moves continuously, and quite fast !  I was surprised when I saw it the first time.  The little differences of temperature in the liquid, caused just by the mild warmth of the hand at the sides of the glass, and the cooling at the surface of the alcohol due to the evaporation, are sufficient to cause the evident convection currents in it.
 
(https://i.imgur.com/ewTjv9R.jpg)

It's not very different with water.  Warmer water is lighter and wants to move upwards. Colder water is heavier and wants to move downwards.  The evaporation of the water makes its surface colder, (I measured the temperature of water in a bucket and it was about two degrees colder that the room temperature). In these conditions the water moves, and even if it moves slowly, it is still too fast for our aims.

For to avoid the convection currents, the water should have the same temperature everywhere in the tank.
The evaporation should be prevented. Maybe a thin film of oil on the water could help ? I don't know.
I suggested to use oil instead of water;  certainly using oil is more messy, but oil practically doesn't evaporate, so I believe that it would be easier to avoid convection currents with it.  Oil is more viscous, but I suppose that, for very slow movements, it is almost frictionless, so it could work.


motor magnets do align with Earth's magnetic field. I may have solved that by shielding the motor with a steel cylinder.

It seems a good idea.

I place a laser pointer on top of the boat in hopes of measuring angular motion. In last test, the pointer oscillated back and forth through 30 degrees for over an hour.

I have read that the simplest gyro compasses can oscillate back and forth, with a period of 84.4 minutes.
84.4 minutes is also the time that it takes for a theoretical satellite at the level of the sea to complete an orbit around Earth, and the two things are related.
But I can't even begin to imagine the reason of it.
 
Title: Re: Shop made gyroscope
Post by: ta0 on October 02, 2022, 10:32:31 AM
Yes, water seems very difficult to control in an experiment that needs to be very isolated from perturbations.

I have read that the simplest gyro compasses can oscillate back and forth, with a period of 84.4 minutes.
84.4 minutes is also the time that it takes for a theoretical satellite at the level of the sea to complete an orbit around Earth, and the two things are related.
But I can't even begin to imagine the reason of it.
I have no idea, but now I'm curious. I need to investigate this.
Title: Re: Shop made gyroscope
Post by: Iacopo on October 02, 2022, 12:11:21 PM
I have no idea, but now I'm curious. I need to investigate this.

It is in the end of this article, (in italian).
But reading it with more attention, it says something different, it says that, according to Max Schuler, if a gyro compass is built so to have a period of oscillation of 84.4 minutes, it will compensate for the errors due to the accelerations of the boat, and it will maintain a more stable orientation. The logicality seems still apparently bizarre, but I know nothing about gyro compasses.

https://it.frwiki.wiki/wiki/Gyrocompas