Spinning a Tungsten Top in a Vacuum Chamber
ฝัง
- เผยแพร่เมื่อ 9 ส.ค. 2023
- In this video I’m attempting to better understand the upper limits of a spinning top. How much does drag affect spin times? How does high rpm influence the way a top spins? How much longer will one spin in a vacuum chamber? This video doesn’t completely answer all of these questions - there are many more factors involved - but it’s a starting point. I hope you enjoy the journey as much as I did.
Tools Used in this Video:
* Tormach Slantpro Lathe
* An old beat up Grizzly Manual Lathe
* BACOENG 2.8 QT Glass Pyrex Vacuum Chamber
* Dremel 8220
* Digital Tachometer DT-2234C+
Where to find Plier Spinning Tops:
*www.etsy.com/shop/PlierSpinni...
* / plierspinningtops
* / plierspinningtops
Thanks for watching, and please don't forget to like, share, and subscribe so you won't miss any future videos. - วิทยาศาสตร์และเทคโนโลยี
Criminally underrated channel, 81 likes is insanely low for content this good. Good luck brother, you'll go far.
Thanks! I appreciate that.
The sound it made on that bigger concave mirror was nice
Nice video, I liked to see it. Hulahooping is a common problem with tops with a ball tip at high speed; you can minimize it by using a littler ball tip, or eliminate it completely by using a spiked tip. 30,000 RPM is a fantastic speed ! For best efficiency in the vacuum, the top should be large, and light, not heavy, (with a high moment of inertia/weight ratio, more precisely); tungsten, which is excellent in the air, is not good in the vacuum. The only problem with a large and light top is that it slows down very rapidly in the air, so the air should be removed rapidly after the top has been spun. Even with a low starting speed, anyway, the spin time can be very long, if the top is specifically designed for to spin in vacuum conditions. Probably you know that I made a top which spun for 4 hours in the vcacuum, starting at about 2200 rpm: th-cam.com/video/Xah0ONSoq1k/w-d-xo.html But I appreciated your attempt. I found interesting to observe the sequences with the smoke, which help understanding how the air moves around the top.
Thanks! I always appreciate your advice! I was thinking that a smaller bearing would help at higher rpm, but didn’t know for sure. Since this top is typically what I make for long spinners, I was curious how it would act in other environments. That vacuum spin of yours is amazing, not sure how I hadn’t seen it. Does top your using have a lower center of gravity than the contact point?
That top has a recessed tip, but not so deeply recessed to be above the center of gravity, so it topples down in the end, at about 50 RPM. With an external tip , a top like that, large and low, would have toppled down at about 150 RPM, spinning about 20-30 minutes less in the vacuum. The recessed tip helps, but the main reason of the longest spin is the high moment of inertia/weight ratio, as said, and as I explained more in detail in the begining of the video.
Thanks!
@@iacoposimonelli7191 With some better sound, camera work, maybe a bit of commentary, and definitely some closeups of the top, that video would have way, way more views. 4+ hours is incredible.
Its the Magnus effect, actually. It doesn't have anything to do with the geometry of the tip aside from the fact that a spiked (carbide, I'm assuming) tip digs into basically any surface its on and prevents the translational motion necessary to induce and maintain the Magnus effect, at the cost of increasing the contact area of the tip with the surface (by pokin a hole in it).
The force from the Magnus effect is proportional to the rpm squared (I think; most aerodynamic forces are), which explains why the effect is so much more pronounced at higher rpms, where if it were a function of just the tip geometry, the top's tendency to precess would be linear with respect to rpm. The fact that the top is stable at 10krpm regardless of the curvature of the surface, but not 15krpm (again, regardless of the curvature of the surface) is a good indicator of the top ejecting itself being an aerodynamic effect and not just a geometric interaction of the tip with the surface.
The constant precession while under vacuum is more of an example of the effect of the carbide ball and the weight of the top causing the top to walk in a circle.
Actually, here's something dumb that you might want to try:
for a concave surface, the Magnus effect and the effect of precession of the top reinforce each other. For a convex surface, however, those two effects counter each other. If everything I just wrote isn't totally wrong, the top should actually be *more* stable on a convex surface for some rpm regime above 10krpm. Because of the square law though, it would be a relatively narrow window. Under a vacuum the Magnus effect would disappear and the top would just walk off the same convex surface at the same rpm.
I sure hope I'm not 100 percent wrong on all of this but I really don't think I am.
Cool video, kinda shocked how much better it did under vacuum. This is the reason guys put vacuum pumps on race engines. If you can pull 20 inches or more on the crankcase of an engine turning 8 grand , it really reduces drag inside the engine.
Fascinating! I had no idea that engineers did that to race crankcases!
@@verysmallcats1374look up how dry sump lubrication works in internal combustion engines. Most race cars use them since a typical oil pan setup allows the engine oil to slosh from side to side under sharp turns and heavy braking/acceleration. That in turn stars the engine of oil and in a race car at 10,000 RPM that is catastrophic. The dry sump system pumps oil in from a reservoir, which maintains oil pressure even under lateral g forces and even when the engine is upside down.
Wow I did not expect how effective that vacuum chamber would be…. Looking forward to the giveaway!
I didn’t either! But after seeing how adding 13,000 rpm to the spin only added 5 minutes of spin time, I realized how much energy is lost to the air.
@@plierspinningtops The top of the vertical axis is too high in height. An imbalance on its longitudinal axis in the upper part, even 0.001 grams, at 30,000 rpm creates a monstrous overload and causes micro vibrations, as a result of which the gyroscope begins to move in a circle and stabilizes only with a decrease in the number of revolutions by about half.
Shorten the top of the axle and you sir will get more impressive results and stable rotation by reducing parasitic vibrations.
I suspect the cross hatched handle grip is doing some pretty crazy things with the air at those kind of speeds.
Very cool demonstration.
Nice to see that you did my idea with the dremel spinning 👍
Yes! Thank you!
4:40 the sides broke the sound barrier. Take that top to the doctor because it is freaking siiiick.
I saw that little puff and heard it too, super cool!
Saw the same thing but the sides aren't moving fast enough for that to happen. That disk has about a 1 inch radius, moving at 30k rpm, means about 180mph edge speed. Unless there's some weird nonlinear stuff going on at the edge interface with the air, I don't see that's the case.
Also, there was no real shockwave that you would expect (i.e., any sort of sharp crackle or bang sound).
Instead I think that the disk was going fast enough to lower the pressure via the Bernoulli effect, and that in turn lowered the condensation point of water vapor in the air. The droplets then made the puff and dissipated.
Edit: just replayed in slow motion and I'm fairly sure this is accurate. The air will take a few seconds to accelerate via the boundary effect (while it trains along with the disk's edge). If you slow the video down, you can notice there's a growing bubble of condensate that eventually "pops". I don't know why it pops suddenly, though.
Thanks for the trip down memory lane. In high school electronics my friend and I built a magnetically levitated pentagonal mirror that we could then spin like the rotor of a motor (based on toy maglev globes but way souped up and a mirror from a photocopier)
We had access to an industrial vacuum chamber and from about 100k rpm it spun for hours! Eddy current losses in the suspension magnets were really the only energy loss.
Also (outside the vacuum) had fun bouncing a laser off a mirror taped to a speaker and then the spinning mirror to make scan patterns of music on the wall...It was an amazing project I'm sorry we didn't document it better.
Well done. I wouldn't have thought air resistance would play such a big role.
There's a type of ultra high vacuum pressure sensor that is essentially a floating, spinning sphere. The energy it takes to keep it at a constant RPM is correlated with pressure.
That was a super cool video. I know that air resistance plays a huge factor. But I didn't think it would affect the top so much it being such a small and smooth object.
This has reminded me of those large spinning-mass Uninterruptible Power Supplies ("Dynamic UPS", "Rotary UPS", "Flywheel UPS") which are available, which have a large spinning mass inside a vacuum, which floats on magnetic bearings to minimise drag even more.
Power input and output is electromagnetic and they only provide on the order of minutes of power after a power outage, but they are intended merely to cover power for the time it takes diesel generators to start up and take over the long term power delivery, until the power outage is over.
2k by hand is a pretty crazy thing to think about.
Love this and just sent it to all my kiddos to watch. 👊 You've got a new sub! Now what is that thing at the end of the vid that looks like it's dripping smoke?
Thanks! The smoke is from backflow incense.
Important QA from the cat! Furreal!
Hahaha!
Damn dude, did you see that vapor being produced from the very fast oscillation @4:43?
I just came to see if anyone else commented on it. Looked like brief cavitation to me.
The sound barrier?
@@admacdo I think this take is correct. I rarely copy and paste my comments around, but this is such an interesting phenomenon that I think OP should make a video about it:
Saw the same thing but the sides aren't moving fast enough for that to happen. That disk has about a 1 inch radius, moving at 30k rpm, means about 180mph edge speed. Unless there's some weird nonlinear stuff going on at the edge interface with the air, I don't see that's the case.
Also, there was no real shockwave that you would expect (i.e., any sort of sharp crackle or bang sound).
Instead I think that the disk was going fast enough to lower the pressure via the Bernoulli effect, and that in turn lowered the condensation point of water vapor in the air. The droplets then made the puff and dissipated.
Edit: just replayed in slow motion and I'm fairly sure this is accurate. The air will take a few seconds to accelerate via the boundary effect (while it trains along with the disk's edge). If you slow the video down, you can notice there's a growing bubble of condensate that eventually "pops". I don't know why it pops suddenly, though.
@@thebestnumber1 So it wouldn't be possible to have the effect sustained since the air around the edge does speed up over time?
Love it.
I like when content creators put titles to explain what's going on, a prime example is in this video at 2:27.
Ha! Glad I could help.
Was that a visual artifact of the video compression or some kind of a puff of smoke at 4:43 ?
i think it wasn’t spinning perfectly true which u can hear by the very fast vibrations, and this vibrations are so quick that it repeatedly creates a tiny vacuum around it which ‘rips’ moisture out of the air
@@hazza2247 Kind of like a propeller in water? I forget what the effect is called, but when it happens in the water it causes pitting on a propeller which will eventually destroy it.
@@anon_y_mousse that’s called cavitation and i see what you’re saying but no it’s not quite the same. like cold air, low pressure air can’t hold water in it well and so when the top vibrates and creates a vacuum around it, the moisture in the air can stay as vapor so it condenses
@@hazza2247 Yeah, cavitation. It's the same in both air and water. There's a whole field of study for fluid dynamics.
@@anon_y_mousse it is not the same in air and water, they both these phenomena happen due to sudden decrease in pressure but they aren’t actually the same thing
Experiments are hard. Great work. I would have put the little ring around the spinning top vs chasing it all the time. Or, in teh bowl, as you did for the vacuum test.
Very cool.
the performance improves dramatically...take your thumb up..
Pretty cool
Fantastic video. You can now calculate what percentage of losses are air drag and whatnis point friction.
Obviously your point friction is very large, that is a big ball bearing and you can see the energy being transmitted into the surface causing the top to wander and chatter. A tiny ball bearing would be much better, maybe 2mm diameter, or a ruby ball.
Thanks! I’ve tested different sized bearings over the years. And surprisingly, the lager ones spin longer. Theoretically, they all have the same size contact point, but I assume there is more contact with the larger ones. I thing the larger ones stabilized the spin a bit and lets the top spin at a lower rpm which adds time. This is all a guess, I could be completely wrong.
Ommgggg
At first I was happy to see this you were using the same little vanity mirror I have, but oh dear… when I saw that 16” concave mirror?!!
I must know where you got that giant thing!? 🤪
The application potentials for it are numerous and I would love to have my own go at them ( with the highest of likelihoods that I will break it at some point lmfao)
The big mirror is from Amazon. Lucky for me for me they accidentally sent me two, because I broke one. Didn’t get it on video though, ha. Thanks
Like for cat.
Catte
could you use one of those magnetic stir plates to get the top going indefinitely ?
4:42 what was that flash? Breaking the sound barrier? Shockwave?
Saw the same thing but the sides aren't moving fast enough for that to happen. That disk has about a 1 inch radius, moving at 30k rpm, means about 180mph edge speed. Unless there's some weird nonlinear stuff going on at the edge interface with the air, I don't see that's the case.
Also, there was no real shockwave that you would expect (i.e., any sort of sharp crackle or bang sound).
Instead I think that the disk was going fast enough to lower the pressure via the Bernoulli effect, and that in turn lowered the condensation point of water vapor in the air. The droplets then made the puff and dissipated.
Edit: just replayed in slow motion and I'm fairly sure this is accurate. The air will take a few seconds to accelerate via the boundary effect (while it trains along with the disk's edge). If you slow the video down, you can notice there's a growing bubble of condensate that eventually "pops". I don't know why it pops suddenly, though.
Just awesome.
The time you saved me from having to go through this myself is appreciated 😀
Step 1 ... buy a lathe.
I believe that part of the stability problem is that tungsten is harder than glass and the top tries to dig into the glass.
I suggest using a composite top with tungsten peripheral and a mild steel as he pivot point.
Use an air compressor to spin the top. Use a metal ball on the top and a magnet to hold it up. Blow the air on the rim to spin it. I didn't know anyone else did this beside me hahaha. I even have the same mirror. I have concave lenses from a projection tv I use too. Silicone on the mirror doesn't seem to help, makes it worse infact. A little bit of friction is required to keep it upright. A small amount of ash smeared on the glass seems to work well.
It would be neat to monitor the speed with an IR tach (would need sharpie marks or something), and monitor the bottom of the plate (maybe paint it black) with a thermal camera to watch for heating from friction (probably negligible but would be cool to see if possible).
Could u use a rotating magnetic field to accelerate and stabilise the top while within a vacuum.
Yes, that may work. I’ve used a magnetic stirrer to keep a top spinning. But it will just spin forever like that until it’s turned off. So maybe stationary magnets under the top would help. Tungsten is slightly magnetic, so I’m not sure if it’s enough to keep the top centered. Another commenter suggested a smaller bearing, maybe a combination of both would help. Thanks!
@@plierspinningtops i mean there is always the option of using a superconductor but i assume that has pinning problem maybe something diamegnectic in a vacuum would allow almost zero friction
Interesting idea, thanks!
So question if you were to design a top that is being spun with the dremal instead of knurling why not machine fins that help with the airflow either pushing down or pulling up. Would that work or am I just thinking weird
No, you’re right. This is the top I made in my previous video to be spun my hand, so it was not made to spin that fast. I think if I were to design a top for high rpm, I wouldn’t have a stem at all, basically just a spinning coin. Thanks!
@@plierspinningtops oh that would be really really cool to see, especially! I love tops wish I could afford a nice top to fidget with to help calm my ADHD lol.
Send me a dm on Instagram or Facebook. I have a lot of tops I can’t sell because of small imperfections; I just give those away (they typically are copper or brass, not tungsten). Happy to send you one.
I'm wondering if the top could run longer if it was hanging from a magnet? Iacopos video mentions that increased weight on the tip can drastically increase friction, and i believe that should negate that problem. Also, project farm did a video on motorkote, which drastically reduces friction, but im not sure an oil would be ok in a vacuum 🤔🤔
I think, in theory, it would. I’ve spun a small top with a tungsten caribe bearing upside down on a magnet. Tungsten carbide is just enough magnetic to hold a small top. The issue is holding up a heavier top. The other issue is that surface of the magnet is not as smooth as glass, causing more friction. Maybe a strong magnet and a thin piece of sapphire would work. It would be worth a try. Thanks for the idea!
4:42 what was that popping sound ? Was that the breaking of the sound barrier?
I said the same thing, it looks and sounds like it did.
is there a shockwave visible ? at 4:42
No, it’s a small piece of reflective tape popping off. I was using it to get a good rpm reading. Quite a bit more boring than a shockwave. Ha
4:43 wow was that a sound barrier boom? :o
I was going to ask the same thing. My jaw hit the floor when I saw that, Had to replay it several times!
I came here to say the same thing!!! Wild
The reason the top went all crazy as the rpms got higher is the Magnus effect which turns the rotational motion of a body (especially anything cylindrical) rotating into a force that pushes the top in a direction perpendicular to the direction its translational motion is in. It's self amplifying, so even a tiny translational motion gets amplified into flying off in a particular direction.
Thanks! I didn’t think of the magnus effect. I was thinking it might be the 1/4” bearing. I wanted to try a smaller bearing and see if it helped. It would be interesting to experiment with a few variables and see what factors are at play. If it was the magnus effect, a vacuum would cancel it out. But I didn’t have the top spinning more than 15k rpm in the vacuum. Thanks for your input!
@@plierspinningtops vacuum wont fully cancel it out since its still transmitting force through the plate. also air drag doesnt increase exponentially, but with the square of the velocity.
I’m no expert in aerodynamics, so I wouldn’t be surprised if exponential is not the most accurate way to put it. But from what I understand, it varies a lot depending on shape. And drag is closer to linear at low velocities and more exponential at higher velocities. But that could be wrong or an oversimplification.
@@plierspinningtops its just the square of the velocity. at low speeds the square and a linear function dont differ much so you can say its approximately linear but really its just square. drag goes with the V^2 * Area * shape * density
@@plierspinningtops I'm just going off what I was taught probably 25 years ago, that in general drag=(drag coefficient)*(velocity^2).
Its very definitely an approximation and breaks down everywhere to some degree.
I remember doing some ballpark guessing when I first saw this video and guessed the outermost part was going 40(ish)m/s? That seems in the "pretty normal" regime for a drag coefficient.
Your tops (tops with radial symmetry in general) probably almost exclusively experience boundary layer friction rather than "flying through the air" drag, but so do things like sailplanes, and drag coefficient seems to work ok for them.
I'm tempted to fire up OpenFOAM (a CFD simulator) but I hate it and it doesn't really like rotating 3D objects.
the sonic boom at 4:40 😲😲
Was really worried for you when that Meou-sha inspector showed up on your worksite.
when i saw the ruby, i knew you mean business
4:42 is that the top‘s outer edge dropping below the sound barrier or something what is that
That's what I thought it was, surprised nobody else mentioned it
Lessen the time to apply vacuum. Have the pump running, and the cover staged at the same level as the bowl top so minimal movement is needed to install it. Some guide blocks attached to the table might also help to quickly center the cover over the bowl.
Good idea! Thanks.
was that a sonic boom at about 4:37?
AWWWW THE KITTY
"Oh, come on!" 🤣
4:41 Did it break the sound barrier ?
Now lets see how long it will go, when using pressurizied air to spin it up.
"OH come on!"
I know that feel...
Spinning a aluminum flywheel will become superconductive at super high rpms🎉
4:42 Was that a sonic boom?
Spin the cat with Dremel in a vacuum
neat
I want to see more of the cat.
Commenting for the rhythm
KITTY!!!!
Nice milling! Not sure if any prototype CNC may help for upcoming content? If so, would love to sponsor and do something together! (PCBWay zoey)
Can be slowed down by magnetic field in immediate area as well!
now make it magnetic, super cool it with liquid nitrogen then spin that up in a vacuum and see how long that goes, so this way you won't even have the friction of the mirror, Would it stay colder longer in a vacuum?
Look you were going to get a like but the moment I seen your cat lol
Ever considered making a gyro with magnetic bearings?
Zero friction would mean you would not even have the axis touching anything.
Make it small, and spin it up with air from a small air line.
I’m talking SMALL, as in relation to your little top.
About the only thing you would need to do is machine some very tiny cups in the perimeter of the disc.
Once this is accomplished, the top should spin for many hours in a vacuum!
4:40 how can that break the sound barrier? The sound barrier is at 333 m/s. at 30000 RPM the top spins at 500/s. That means in order to break the sound barrier the circumference has to be 66 cm so the top needs to be 20 cm in diameter. That makes no sense so it should be another effect that causes this phenomenon?
It’s far less interesting than breaking the sound barrier. That pop is a small bit of reflective tape shooting off. I used the tape to make the rpm reading easier.
I see, now make a 20 cm spinningtop break the sound barrier@@plierspinningtops
Next step: magnetic levitation?
Never lend this guy any optics 😅
Ha! I’ve ruined quite a bit of nice optical glass.
Did anybody see the mini sonic boom on the mirror?😮
It really went for 1 hour 25 minutes?
This entire video could have been a picture instead.
make it spin with a magnet underneath
I have a magnetic stirrer, which will work on this top because tungsten is just magnetic enough to keep the top spinning. It will spin as long as it’s on.
2:30
Sir, you didn't give us the cat's weight, dimensions, or composition.
1 demerit.
thats makin some wack sounds 4:30
This guy stole my idea for a video.
Glad I did not start making it yet.
Sorry about that. But you should still make it. There a a lot of good suggestions here in the comments on how to get more spin time in the vacuum. If I were to do it again, I’d use a smaller bearing, and try a few more surfaces to spin on. And maybe go with a bit heavier top.
@@plierspinningtops haha, was not even remotely serious. This is amazing sir and I would not have the skill, patience, or equipment. As far as programming goes, this is niche as one can find--keep up the great work.
A CONVEX floor plate might hold tops better, perhaps for the same reason the wheels that hold ribbon belts are convex.
....
The top of the vertical axis is too high in height. An imbalance on its longitudinal axis in the upper part, even 0.001 grams, at 30,000 rpm creates a monstrous overload and causes micro vibrations, as a result of which the gyroscope begins to move in a circle and stabilizes only with a decrease in the number of revolutions by about half.
Shorten the top of the axle and you sir will get more impressive results and stable rotation by reducing parasitic vibrations.
Definitely. Thanks! I’ve made some tops without stems in the past; basically spinning coins. A design like that would be much better at high rpm.
@@plierspinningtops 👍
CAT
Now shoot some electrons at it
It is simply unbalanced. It has to be dynamically balanced for the speeds you're trying. Also the ball tip make it difficult to have a consistent point of rotation
Remove this spinning thing, bring back "cat".
Ha! My secret plan is to slowly transition from machining to cat content.
Expectation: Could spin for hours, maybe a couple days.
Reality: less than a minute and a half.
Timer is sped up. Watch from 5:21 onwards to see. You’re interpreting as minutes and seconds; the spin time is in hours and minutes.
CAT