iTopSpin

Top spins with a very slight wobble on the counter but an annoying rapid wobble on the base. Since self-righting is weak on the counter but strong on the base, I'm not getting
the stately wobble-free precessions seen in the video

Sounds like the bearing balls of the base are not spinning well. Have you tried to lubricate them?

My poor english... ok, the counter is very simply the "table", and the base is the piece with the three ball bearings.

Jeremy, if the self-righting in your gyro is too fast, I believe that the reason is that there is too much friction in the bearings inside your gyro. You could clean those bearings with some solvent and lubricate them with oil, this should solve the problem.

I like the design of that gyroscope. The idea of the three ball bearings in the base is brilliant; they make for a very low rotational sliding friction, this low friction helps the rise of the gyro. It is possible to decrease the speed of the rise, or even to stop it, also by increasing the friction of these bearings, maybe by using a bit of grease in them.

It is cool that the tip for the base is shaped like a ball, with a thin neck. This allows for the gyroscope to spin on the base with a really very tilted position, maybe even more than 90 degrees. It would be interesting to see if the gyroscope can rise, at least a bit, from a so low position. Theorically, as far as I understand, it can't rise at all from there, because at 90 degrees of tilting the effect of the rising torque is totally canceled.

Iacopo wrote: Theorically, as far as I understand, it can't rise at all from there, because at 90 degrees of tilting the effect of the rising torque is totally canceled.

I don't think it makes a difference. If the external torque stays in the same direction, it will raise the gyro/top that is at 90 degrees or even if it's below the horizontal.

ta0 wrote: I don't think it makes a difference. If the external torque stays in the same direction, it will raise the gyro/top that is at 90 degrees or even if it's below the horizontal.

I am assuming that rolling resistance is the cause of the rise.
In a normal top the rolling resistance is a torque about an axis which is always horizontal, (or, to say better, an axis which is always parallel to the spinning surface), whatever the angle of tilting of the top.
The base with the three ball bearings makes the picture more complicated but I believe that there is still resistance to rolling with the same effects of the rolling resistance of a normal spinning top, and that this resistance is still a torque about an axis which is always horizontal.
If the gyroscope is tilted by 90 degrees, the axis of the rolling resistance torque becomes aligned with the axis of the gyroscope;
in this condition the component of the torque wanting to tilt the flywheel disappears, and the only effect of the rolling resistance is that to slow down the spin speed of the gyro.
When the gyro is below the horizontal, the effect of the rolling resistance becomes reversed, it pushes the top downwards instead of making it rise, so the gyro can only sink down at this point, since the other torque too, (the friction torque about the vertical axis), is in the direction to make the gyro to sink down.

I desume from my experiments that generally friction torques about the horizontal axis, (like rolling resistance), make the top or gyro to rise, and that friction torques about the vertical axis instead, (like rotational sliding friction), make the top or gyro to sink down. Anyway when I tried to measure and calculate the magnitude of the forces in play, it seemed like rolling resistance by itself is a bit weak for to justify the speed of the rise, so there is something I am missing.

For this reason I was curious about the behaviour of this new gyroscope.
Maybe Jeremy could tell us if the gyroscope can rise from a very tilted position.

On a fall color road trip in the mountains with very little signal. Will try some experiments when we get home.

Two videos about magnetic (tip) tops:

https://www.youtube.com/watch?v=59Z73xfH0GU

https://www.youtube.com/watch?v=sJv26cEBRXs

The page he shows from Gould's book is from a French publication (La Nature, 1896) so I'm not sure if they should be called Victorian (although some may be English). The article was translated to English and publish in Scientific American the next year.
The one with the magnet horseshoe (#41) is a different type of top. I believe the top itself is not magnetic but of a conductive metal and just shows the effect of eddy currents.
The last top he shows, with the clear acrylic, I got from the Grand Illusions shop, and it's indeed very nice.

I found this US patent from June 7, 1910, by Charles J. Schneider of New York:



As you can see, the patent already showed a nice serpent.

ta0 wrote: The last top he shows, with the clear acrylic, I got from the Grand Illusions shop, and it's indeed very nice.

A very nice but pretty obvious design change. Wonder why it took so long to come to market? Cost? Fabrication issues? Clear plastic's been around a long time.

The big question is, what happens when you plug the stem into a stereo audio jack and give it a spin?

---

BTW, this and several other tops from Tim's videos are also available from The Toupie Shop.

https://www.toupie-shop.com/acheter-tou ... ue-11.html

Grand Illusions carries only a small fraction on the tops Tim shows. If you just have to have one and can't find it there, you might check The Toupie Shop. The offerings may not be the same.

Jeremy McCreary wrote: A very nice but pretty obvious design change. Wonder why it took so long to come to market? Cost? Fabrication issues? Clear plastic's been around a long time.

Many things are obvious after the fact, but not necessarily before.

This toy solves the blocking problem by moving the "serpent" above the "top":

https://www.youtube.com/watch?v=ht8tfwC5Hl8

Although it's not really a top (the internal top is supported and cannot fall), I was interested as it has to do with another hobby of mine, tango dancing. I got the Tango Top from Lassanske's collection. He had several versions with advertising graphics, but this is the original with the tango dancing couple. It says patented March 21, 1916, both on the toy and the box, but the patent I found is from September 19th. It was issued to Geroge H. Reimer from Falton, Illinois.

Jeremy McCreary wrote: Top spins with a very slight wobble on the counter but an annoying rapid wobble on the base. Since self-righting is weak on the counter but strong on the base, I'm not getting the stately wobble-free precessions seen in the video.

Overall, I'd say worth at most half the price.

Update on the big stainless steel coax top/gyro: First, I goofed. The "annoying rapid wobble" I reported above occurs only with the rapidly spinning tip on the loose ball-bearing base. Guessing the base wasn't intended for that kind of speed, but have not tried lube.

The good news: Those "stately wobble-free precessions seen in the video" were obtained with the very slowly spinning stem on the base. And that's what I get, too.

Have yet to find a large effective surface for the Wizzzer-like rolling starts -- at least not one I'm willing to mar. Nor have I had time to put in the practice this starting method clearly needs.

But I made a very effective high-speed LEGO starter with a small rubber tire driven by the most powerful LEGO motor ever made. Whee doggies! Gyroscopic rigidity is very impressive with the starter. And so is the play value.

So now I see the big stainless steel coax top/gyro as a clever and elegant but very pricey spintoy with excellent play value once you get it up to speed. Kinda like a Ferrari.

Jeremy McCreary wrote: The "annoying rapid wobble" I reported above occurs only with the rapidly spinning tip on the loose ball-bearing base. Guessing the base wasn't intended for that kind of speed, but have not tried lube.

The good news: Those "stately wobble-free precessions seen in the video" were obtained with the very slowly spinning stem on the base. And that's what I get, too.

I believe that the ball-bearing base is only for the "stem", (the ball with the thin neck), not for the "tip".
The ball-bearing base allows for rotation only about the vertical axis;
so, it works well with the "stem" ball tip, which is not spinning; there is only precession, and precession is about the vertical axis, so it works fine.

The "tip" instead spins, and if the top is tilted, the spin is about this tilted axis, so the "tip" has to grind against the three balls of the base which do not allow for this tilted rotation. I am not too surprised if in this case there is some wobble.

Iacopo wrote: I believe that the ball-bearing base is only for the "stem", (the ball with the thin neck), not for the "tip".

Agree. The loose base ball bearings aren't prepared to handle operating tip speeds-- at least not smoothly.

Since the internal bearing between tip and stem is good but not perfect, the stem both spins and precesses when on the base with the tip at operating speed. And the base bearings happily accommodate this combined rotation, some of which is not about a vertical axis.

The stem's spin rate in that case is only a small fraction of the tip's. However, it looks to be significantly above the precession rate.

More experiments today with the big stainless steel coax top/gyro (center) and this equipment...



The wooden pull-out cutting board is my best surface yet for wizzzer-like rolling spin-ups. Its competition, the motorized LEGO starter on the right, was powered by the 9V LEGO train transformer on the left. The ball-bearing base was not used.

Both starting methods take some skill. After practicing each for several minutes, I measured spin times (from release to first scrape) on the slightly concave glass lens in top mode (with tip down as shown).

Best spin times:
Rolling spin-up = 6 m 14 s = 374 s
Motorized starter = 6 m 44 s = 404 s

Spin times varied quite a bit with both methods but less with the starter.

Haven't measured release speeds directly for technical reasons, but the fastest release speed here clearly goes to the starter. This is corroborated by the fact that the top usually tried to climb out of the lens with the starter but never with the rolling spin-ups.

Jeremy McCreary wrote: And the base bearings happily accommodate this combined rotation, some of which is not about a vertical axis.

It happily accomodates only the rotations about the vertical axis.
The rotations about the tilted axis can happen only by slipping of the stem ball surface on the surfaces of the three balls of the base, even in the case of combined rotation. You can see this by playing with a ball on that base.

Only when the top spins in sleeping position, the base bearing accomodates for the spin movement, which at that point is about the vertical axis.
The friction between the stem ball and the base, braking the spin motion, should decrease significantly when the top reaches the sleeping position.

I can't see the rotational speed of the stem in the video, but I can see the rotational speed of the three balls in the base, they accelerate when the top almost reaches the sleeping position, telling that the stem too is accelerating, this happens because the friction between stem and base is diminishing so the stem is more free to follow the speed of the tip.

A video titled "Tim and the Four Tops" but it's not about a 50's band.

https://www.youtube.com/watch?v=8aJGrJg9UkQ

Tim discovered Spinjitzu.

The second one is a prototype of a series of tops based on regular solids. I bought them directly from the independent inventor but later they were licensed by Duncan. Duncan doesn't offer them anymore, but when I went to the Duncan site (yo-yo.com) I found this notice: "Due to the COVID-19 outbreak, we are experiencing delivery service delays and unprecedented volume of orders." Perhaps a new yo-yo boom fueled by the pandemic is brewing! Unfortunately, the only tops on the site are the Imperial and Gyro Racers

salut Jorge
very entertaining vid as usual
i enjoyed every minute of it

and there's the suitcases in the back ....


I wish we could invite Tim to Marines in a dreamy future

jim