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Clutch tops
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Most tops have built-in stems for spin-up purposes, but it doesn't have to be that way.
About this creation
Please feel free to look over the images and skip the verbiage.

The "clutch tops" presented here have detaching drive shafts coupled to their rotors only during spin-up. The 4 "main" clutch tops are named by color: White, Red, Yellow, and Lime.



Each has a rotor based on one of my favorite studded top foundations -- a ring of 6x6 sloped round corner bricks (95188) on a 10x10 octagonal plate with center hole (89523).



Torque is transferred from drive shaft to rotor via dog clutch in White and Yellow and via centrifugal clutch in Red and Lime.

Each clutch type has a "male" and "female" half. I name the clutch after the gender and type on the rotor and call the detachable half the "driver". Hence, Red above has a male centrifugal clutch and White, a male dog clutch.



Here we have the main tops being spun up with various top spinners. Their clutches encompass all 4 type-gender combinations, but only 3 different drivers are needed, as Red and White take the same one by design.



I personally prefer the 2-stage planetary spinner below because I like its mechanical feel.



However, the electric spinner and wind-up spinner above also work well.

The spinners generally make for easier start-ups, cleaner disengagements, and longer and smoother spins, but clutch tops are also easy to "twirl" (spin up by hand).



This long video starts with the 4 main tops and ends with 4 additional tops described below.

On this page:Warning! Always wear eye protection when working or playing with high-speed LEGOŽ rotating machinery and keep valuables and bystanders (including pets) a safe distance away -- especially when testing new designs.




Main top comparisons

Yellow and White both have dog clutches -- respectively, female and male.



Tops with dog clutches are easier to couple up and start up than those with centrifugal clutches. That's especially true of female dog clutches like Yellow's. Dog clutches also yield the quickest and cleanest disengagements.

Red and Lime both have centrifugal clutches -- respectively, male and female.



The male halves of these simple centrifugal clutches bear 3 freely pivoting black Technic rubber connectors. Centrifugal force pushes these "grippers" outward at speed. The female halves use 31x15 mm Technic wheels as "drums" (the enclosures the grippers are designed to grip).

Red's male centrifugal clutch is easier to couple up than Lime's female and also separates more cleanly.

Red and White both have male clutches. Despite the differing clutch types, both use the same female driver by design.







The protruding central axles guide the driver home during coupling and keep Red's centrifugal clutch centered during spin-up.

The female centrifugal clutch on Lime's rotor takes a dedicated male driver.



It's rather fiddly to couple up and keep centered during initial spin-up but centers itself nicely at speed.

The female dog clutch on Yellow's rotor also needs its own male driver. This clutch is the easiest of all to couple up.



All main tops use my preferred tip.



Little separates the main tops aerodynamically, but Lime and Yellow are the cleanest, and Red, the dirtiest. Since White weighs the least (37 g), it sees the least tip friction, but not by much. The other 3 have nearly identical masses (39-40 g).



The tops are also pretty evenly matched in axial moment of inertia (AMI). Lime has the greatest transverse moment of inertia and the highest CM as well. These parameters are nearly equal in the other 3.

All main tops put in good spin times by hand: 65 sec for White, 60 for Yellow, and 55 sec for Red and Lime. The spread mainly reflects the higher release speeds attainable with the dog clutches. Lime wobbles least.

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Other tops in 2nd video

The 2nd video (the one showing the main tops being twirled by hand) includes 4 additional tops for comparison purposes.

These 2 tops use rotors and tips like those on the main tops but have built-in drivers (stems).




The "jungle top" is one of my all-time favorites.

The wheel tops below have female dog clutches just like Yellow's. I included them to show that clutch top rotors and tips aren't limited to those on the main tops.



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Engineering notes (optional)

As mentioned, the 4 main tops use the same rotor except for ornamentation. This rotor has 2 desirable attributes: (i) A center of mass (CM) close to its bottom surface, and (ii) a high AMI per unit mass. (See my AMI primer for details.)



These rotor properties reduce the precession and wobbling (nutation) likely to follow imperfect disengagements by lowering the CM and increasing the AMI of the top as a whole.

After some experimentation, I settled on 3 as the best number of dogs in a dog clutch.



Remember that famous 70s cover band, "Three-dog clutch"? No? Well, maybe it was Three Dog Night. Anyway, the band apparently knew a thing or two about clutch tops.

The band, you will recall, deemed 1 the loneliest and saddest number -- no doubt because a 1-dog clutch would be a non-starter in a clutch like Yellow's. White still works with a single dog but not smoothly and only because of its central guide axle.



The band also had their doubts about the number 2, and sure enough, I found 2-dog clutches prone to sloppy disengagements. These often left the tops precessing and wobbling (nutating) to beat the band.

Tellingly, the band had nothing bad to say about 3, as that's the happiest number when it comes to dog clutches on tops. Additional dogs add nothing of value and make coupling more difficult.



They wisely chose not to weigh in on whether the dogs should go on the driver (Yellow) or on the rotor (White), as the answer depends on whether you're more attracted to easy coupling (Yellow) or a driver that also works with a centrifugal clutch (White).

The detachable driver for a clutch top is on the driving shaft by definition. In real-world centrifugal clutches, the grippers go on the driving shaft, and the drum, on the driven shaft.

Lime's female centrifugal clutch follows suit in putting the (female) drum on the rotor. The (male) grippers then mount on the driver.



However, Red's male centrifugal clutch does just the opposite. This bass-ackwards approach would never do in a chainsaw or go-cart, but it makes sense in a clutch top for at least 2 reasons.



First, a male centrifugal clutch is less fiddly to couple up and keep centered during spin-up. Secondly, a female driver like Red's can easily be made to work with a male dog clutch like White's, but the male driver for a female centrifugal clutch like Lime's can used with no other kind.

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Specifications (main tops only)
(Specs that differ from top to top are given in "Yellow,White,Red,Lime" format.)

Construction:Studded
Clutch types:Female dog,male dog,male centrifugal,female centrifugal
Rotor diameters:96 mm
Overall heights:36,38,43,44 mm (excluding drivers)
Masses:39,37,39,40 g (excluding drivers)
Best spin times by hand:60,65,55,55 sec
Typical release speeds:n/a
Modified LEGOŽ parts:Tips cut from 4L round-tipped antennas
Non-LEGOŽ parts:None
Credits:Original MOCs
See also:Planetary spinners, electric spinner, and wind-up spinner

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Comments

 I made it 
  May 19, 2016
Quoting Jack Sparrow Wow. As always, your attention to detail and explanations blow me away. I meant they're tops but you really make them more interesting. Thank you!
Thanks for those very kind words, Jack!
 I like it 
  May 16, 2016
Wow. As always, your attention to detail and explanations blow me away. I meant they're tops but you really make them more interesting. Thank you!
 I made it 
  March 23, 2016
Quoting Vibor Cavor This is a super cool idea. This should definitely be suggested to LEGO IDEAS!
Many thanks and good suggestion, Vibor! I'm working on a top-related submission for LEGO ideas.
 I like it 
  March 23, 2016
This is a super cool idea. This should definitely be suggested to LEGO IDEAS!
 I made it 
  March 20, 2016
Quoting Oliver Becker Hey Jeremy, what a bunch of fine tops here again, my friend! You're the master of spinning disaster of the world, I believe... ;) Go and get the next one here to present as a wonderful "spin- off" of the other kind... LOL :)
Too kind, Oliver! Well, one thing's for sure: I'm very good at amassing LEGO tops. I now have enough tops to cover ~4 square meters of table space with more on the drawing board.
 I like it 
  March 19, 2016
Hey Jeremy, what a bunch of fine tops here again, my friend! You're the master of spinning disaster of the world, I believe... ;) Go and get the next one here to present as a wonderful "spin- off" of the other kind... LOL :)
 I made it 
  March 16, 2016
Quoting Oran Cruzen They are all super duper! Have you tried to upload a new MOC in the past couple of days?
Thanks, Oran! Yep -- the text uploaded just fine, but image uploading was broken. The first indication that the images weren't uploading properly came on the first page meant to show their thumbnails. But instead of thumbnails, there were only "X" symbols.
 I like it 
  March 15, 2016
They are all super duper! Have you tried to upload a new MOC in the past couple of days?
 I made it 
  March 15, 2016
Quoting David Roberts More fascinating stuff. When's your PhD being published? Can you get grant funding to support your research? (i.e. get other people to pay for your LEGO!!). I like the 2 stage planetary spinner too, simply because of the concept of a planetary gearbox in Lego. It's still impressive how you used those ugly wheels/cogs. It's interesting how the type of clutch and how high it goes effects the CM and therefore the stability. I didn't realise that small changes in height and amounts of fairly light Lego would have that much influence. As a side note, Google obviously reads your write-ups. I'm constantly seeing adverts for spinning tops on the Google ads on various webpages! It makes me smile and reminds me of your experiments :D
Thanks, David! Current funding comes from a matching grant of sorts: Whatever my wife spends on shoes, I get to spend on LEGO. The good and bad news: It works both ways. In my experience, top behavior is more sensitive to CM height than any other parameter. However, the effects are hard to disentangle from those due to transverse moment of inertia, as the latter also varies strongly with CM height. Wow, didn't even notice those top ads until you mentioned them. Hmmm, we've seen a string of racy silhouettes here lately. Can't wait to see what kind of ads they're attracting!
 I like it 
  March 13, 2016
More fascinating stuff. When's your PhD being published? Can you get grant funding to support your research? (i.e. get other people to pay for your LEGO!!). I like the 2 stage planetary spinner too, simply because of the concept of a planetary gearbox in Lego. It's still impressive how you used those ugly wheels/cogs. It's interesting how the type of clutch and how high it goes effects the CM and therefore the stability. I didn't realise that small changes in height and amounts of fairly light Lego would have that much influence. As a side note, Google obviously reads your write-ups. I'm constantly seeing adverts for spinning tops on the Google ads on various webpages! It makes me smile and reminds me of your experiments :D
 I made it 
  March 5, 2016
Quoting Didier B Jungle top : 5/5 !
Thanks, Didier!
 I like it 
  March 5, 2016
Jungle top : 5/5 !
 I made it 
  February 29, 2016
Quoting Nick Barrett Three always was the magic number.... love these, especially the jungle top.
Thanks, Nick! Just occurred to me that the jungle top could be turned into a clutch top with a 4-dog driver.
 I like it 
  February 28, 2016
Three always was the magic number.... love these, especially the jungle top.
 I made it 
  February 27, 2016
Quoting Topsy Creatori Ha, ha... these would make for great EDC tops... no shafts to poke thru a pants pocket! BTW, after viewing that last posting of yours I did some searching on Youtube and found this... https://www.youtube.com/watch?v=MENrEgvGh94
Perfect, Topsy! Then I could out-do all those other EDC guys on (top) size alone. Interesting that you found that particular video, as it was my first glimpse at the EDC phenomenon. The tops in the video are perfect examples of the "exquisite metal objects" prized by EDC buffs. Some are pretty amazing.
 I like it 
  February 27, 2016
Ha, ha... these would make for great EDC tops... no shafts to poke thru a pants pocket! BTW, after viewing that last posting of yours I did some searching on Youtube and found this... https://www.youtube.com/watch?v=MENrEgvGh94
 I made it 
  February 26, 2016
Quoting Jimmie Martinez WOW, these creations are as brilliantly designed, flawlessly functioning, and showcased to the nth degree as the beautiful piece of classical music in the videos. BOAJEWD.
Too kind, Jimmie! For some reason, classical music and tops just go together -- especially allegro stuff from Mozart, Mendelssohn, and Bach. A musician friend thinks it has to do with the way tops move when they're not sleeping, and the way those movements interact with the layers of rhythm in such pieces.
 I like it 
  February 26, 2016
WOW, these creations are as brilliantly designed, flawlessly functioning, and showcased to the nth degree as the beautiful piece of classical music in the videos. BOAJEWD.
 I made it 
  February 24, 2016
Quoting jds 7777 So now we have clutches in tops! Next we will se tops with rubber bands built into them to keep them spinning longer! And then top spinners with transmissions! Keep 'em comin' Jeremy! Actually, I think the jungle one is my favorite.
Thanks, JDS! Agree, the jungle top is the best one here. It's also very popular at shows. Coming soon: A top that harnesses the rotational kinetic energy of passing vortices in the subspace tachyon field, which as you know are like little dust devils in the fabric of space-time.
 I like it 
  February 24, 2016
So now we have clutches in tops! Next we will se tops with rubber bands built into them to keep them spinning longer! And then top spinners with transmissions! Keep 'em comin' Jeremy! Actually, I think the jungle one is my favorite.
 I made it 
  February 23, 2016
Quoting Nerds forprez The innovation continues. Wonderful post. I love that someone else not only likes to create and build in Lego.... but also likes to "play" with Lego. By that I mean experiment, test, document, etc....
Thanks, NFP! That bit about play describes technical LEGO to a "T" in my mind. It's more than just a string of MOCs. It's an empirical process -- one that you and I happen to enjoy a great deal. And as you well know, there's just no substitute for working a gizmo with your hands to improve your sense of (i) why and how it works as it does, and (ii) how it might work better.
 I like it 
  February 23, 2016
The innovation continues. Wonderful post. I love that someone else not only likes to create and build in Lego.... but also likes to "play" with Lego. By that I mean experiment, test, document, etc....
 I made it 
  February 23, 2016
Quoting The Royal Brick Very interesting! I like the look of the tops without stems while they spin - they look simpler in a nice way.
Thanks, TRB! They strike me the same way. The main tops make me think of hovering flying saucers.
 I like it 
  February 23, 2016
Very interesting! I like the look of the tops without stems while they spin - they look simpler in a nice way.
 I made it 
  February 23, 2016
Quoting Walter Lee Amazing - very clever.
Thanks, Walter!
 I like it 
  February 23, 2016
Amazing - very clever.
 
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