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[Bill Wells]

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

[Jeremy McCreary]

Beautiful in both design and execution, Bill! Please let me know when mine's ready.

Enough procrastination -- back to packing.

[the Earl of Whirl]

Very interesting!!!

[Bill Wells]

Very interesting!!!

Thank you. Interesting yes, and perplexing. Still trying to understand the physics.

[Iacopo]

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

[Bill Wells]

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

[ta0]

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.

[Iacopo]

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.

[Bill Wells]

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.

[Bill Wells]

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.

[ta0]

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

[Bill Wells]

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.

[ta0]

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.

[Bill Wells]

...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.   

[ta0]

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.