LEGO Mechanical Speed-Graphing System

[@Mariano.Bernacki]

The brake mechanism you reinvented is called a "Sprag Clutch", and it is used in helicopters so that power can be transmitted from the engine to the rotor blades, but if the engine fails or the transmission seizes, the blades can still spin freely so you may autorotate (helicopter gliding) to a safe landing. It transmits torque in a single direction.

[@bukowskii]

Also very similar to trailer brakes, the magnet does not have the power to stop the the drum but has enough power to "jam" the shoe into the drum and then the rotation of the tire does the rest.

[@NmpPnm]

D8sc* (yes 8 8ncluded)

[@MaddiMäddi-p7x]

It‘s probably one of the best Lego Technic vids I‘ve ever seen! Who else agrees?

[@PCrailfan3790]

I do

[@BananaGearStudios]

Wow, thank you so much!

[@antoniozhang6055]

Me too!! so many mechanisms ❤

[@marcuscurrie7233]

i do

[@lsf3og]

Yep

[@guard13007]

The Schmitt linkage (or however its spelled / named sorry memory bad) made me so excited cause I've watched so many "simple mechanisms" / "simple machines" in Lego videos and they always demonstrate the concept, but never show an application of it (which, to be fair, isn't the point on those videos) and I'm just so excited to finally see someone using them practically!

[@BananaGearStudios]

That's really nice to hear, I'm glad you liked it!

[@Tydwhitey]

@@BananaGearStudios I was also going to mention how I giddy I got when the Schmidt linkage came into play! And just like @guard13007 said, it's always been one of those things I've seen demonstrated, but until now I'd never seen it I've seen it implemented. Bravo!

[@Budder99]

This is so incredibly clever and well thought out, I can't believe it doesn't have more views! You explained everthing so well I was able to keep up and appreciate each step and part!

[@BananaGearStudios]

Thank you so much! I'm really glad you liked it!

[@NmpPnm]

​@@BananaGearStudiosRESPOND

[@Blazico]

Cool video! As an electrical engineering student I have learnt a lot about sampling digitally in the electrical domain so I know the theory you discussed at the end of the video. It never dawned on me that this theory is also applicable to mechanical systems in the exact same way!

[@BananaGearStudios]

Thanks! I know, I also thought it was really cool that principles you normally only see in electrical systems can occur the same way in a mechanical system like this.

[@BananaGearStudios]

Good point, I'm always having to account for it too when editing these videos - most of the clips are actually sped up/slowed down between like 80% and 120% speed to line up with me talking, but I always know to stay well clear of 50% or 150% speed because it means 1 in 2 frames gets skipped and it looks really juttery.

[@dragoncoder047]

Technically this is a position-graphing machine, not a speed-graphing machine, but doing a derivative mechanically is really hard - even the fly-ball governor is not perfect. But leave it to this man to eventually come up with something that actually does this - I'm just thinking, maybe a combination of a conical pendulum and a torque amplifier and connect that to a really big fly-ball governor. I'm already anticipating the next video!

[@mutekn0wm0re82]

You could probably introduce one of those mechanical differentiators into the system.

[@Spicii9896]

​@@mutekn0wm0re82that would be so sick to see

[@EuphemiaRem]

With the mechanism shown in the video, it might be possible to use a spring to reset the pencil at the end of each “tick” along the graph, to replicate the mean value integration on the dial system. Getting the timing worked out would be tricky but it seems physically possible

[@computeraidedworld1148]

Yeah he says that in the video.

[@virtualfpv3568]

This has to be the most interesting lego machine I've ever seen. The second I saw the discrete measurements, I was thinking about Nyquist; hearing you mention Nyquist made me so happy!

[@mxfxmmuller1778]

Really good! Also a very nice demonstration of digital sampling and the niquist theorem!

[@BananaGearStudios]

Thanks!

[@BrickAutomaton]

At this point this is more like ingenering than building with lego🔥 keep going yout build are awsome!!

[@BananaGearStudios]

Thanks so much!

[@isaacmurray8490]

Lego now offers the slip gear, white boxy gears with a light grey axle collar in the center. These are useful for bypassing systems of extreme torque backlash, like, say, when the escapement is stuck for a second because that’s how it works. Because they escapement works by creating a brief moment of very high torque then releasing said torque, using a slip gear as an input point and a solid gear as the connection between the two, you can use a motor to power a chain which could be an infinite escapement force that never needs wound.

[@just_Ro]

17:09 The Shmitd Linkage came in so unexpectedly... Amazing showcase of engineering and mechanical knowledge!

[@MrAwawe]

Amazing! I love how many maths and science concepts you managed to explain over the course of the video. You really have a knack for education.

[@techman2553]

Great build, and very clever ! If I were building this myself, I wouldn't be happy until I figured out how to lay the paper down flat and draw on it like a typical plotter. I always love those things ! Fun fact: The old phrase "going balls out" refers to the fly-ball governor mechanism. The balls ( or weights ) are furthest out when it is spinning the fastest. Going "balls out" means going fast.

[@andreacarpi2971]

Great quality! Love the way you explain complex topics with legos!

[@lucasguythebest]

Bro deserves so much more than 11k subscribers 😭😭😭

[@biggie_kellogs7919]

wow super cool stuff! Bringing back to memory a lot of stuff i learnt in my engineering degree!

[@BananaGearStudios]

Thanks, glad you liked it!

[@deadcat7026]

my mind is blown, incredible!

[@BananaGearStudios]

Thank you, I'm really happy you liked it!

[@alexroberts4504]

Love how you worked out self servo action for the brake, it is actually used in cars, but only on drum brakes; for the leading shoe only, or on old stuff with 2 slave cylinders to push both shoes out as a leading shoe, drum brakes are only on the rear of smaller/cheaper cars these days.

[@KidarWolf]

This is fantastic - love the explanations, they're simple enough to be understandable, while still being right. Very nice build, and excellent video!

[@BananaGearStudios]

Thank you! I'm glad you liked it!

[@tomekoregano]

Great work 👀

[@BananaGearStudios]

Thank you!

[@meow-tr8uj]

1:39 danm that transition was smooth!

[@izzino6794]

this was some nice quality video ! i sat through it all and enjoyed it a lot even though i never watch lego Technic videos. good job mate! i hope this video will recieve the credit it deserv

[@BananaGearStudios]

Thank you! I'm glad you enjoyed it!

[@scottmuench6855]

Thank you for relation the physical world to the mathmatical concepts

[@BeesKneesBenjamin]

This man literally building a mechanical digital integrator. This is such a beautiful system, good job!

[@TheLegoAnimator863]

this is useful for some real life applications so well done❤

[@sage5296]

The nyquist-shannon sampling theorem is also why a 48kHz digitally sampled audio is indistinguishable (to a human) from an analog sample. Any frequency less than half (plus a small extra factor) the sampling rate can be recreated flawlessly, and humans generally can't hear anything above 22kHz (Down to as low as 12-15kHz as you get older/lose your hearing)

[@derpyyume]

This is insane, favorite lego channel to watch!

[@BananaGearStudios]

Thank you so much!

[@RealEverythingComputers]

Great video! You should have way more subscribers just because of this video!

[@BananaGearStudios]

Thank you for the kind words!

[@NickName212]

why is this getting like no views? Its incredible, i never could be able to make something like this!

[@BananaGearStudios]

Thank you! And hey, thousands of views ain't nothing to complain about, but I'm glad to hear people like it.

[@NickName212]

I know, but like compared to others you make amazing stuff, you deserve more views.

[@Raul-pg1pf]

I'd say it's because he goes on and on explaining small details in these videos, it's not extraordinarily entertaining. The explanation of the breaking mechanism for example felt overly verbose and frankly like a drag on, while it's actually pretty clear how it works. I take it he's very proud of it, which is fine, but being clear and brief is key if you want to reach more people.

[@parmsib]

Didn't expect a LEGO video to mention Nyquist sampling theorem. Great video though!

[@pg5200]

Very cool video indeed, it made sense all along. Loving how you detail the building/engineering process !

[@MazeFrame]

I am glad I clicked on this video! Fantastic work!

[@mikeydelamonde]

Brilliant video and completely unique to me! Well done- loved it!

[@girpe5635]

This explains the ticking on hasler bern tachometers! Thank you very much

[@rj5529]

6:54 drum brakes actually do kind of work this way, the leading shoe has a self servo effect which helps with braking, older cars with front drums would have what's called a double leading shoe arrangement to help increase the effectiveness of drum brakes.

[@TheCursedModder]

Wow this was really cool. Learned some things

[@Adl_LP]

Simply INCREDIBLE!!!!

[@NT-zf8dx]

蒸気機関車の速度計に時計装置があるものがあります。これは進行方向が変わっても問題ないように整流機構も組み込まれています。

[@Pystro]

You could probably make a device that graphs actual speed if you connected the motor to the dial, and then had a pendulum-driven mechanism that periodically reset the dial back to zero.

[@BananaGearStudios]

That's a nice idea. Could be a little tricky to make it work, but it could be something I'll try in the future.

[@zombieregime]

Im gonna be that guy for a second... Uhm, actually, cars did use a brake setup similar to that. The shoes of drum brakes would pivot on one end and have a piston on the other, when the brakes is pressed and fluid is pushed through the system the piston presses the shoes into the internal face of the drum housing. One shoe would be trailing, but the other one would be leading. However, due to the design of the system and materials used (and some honking strong return springs) the scenario of jamming the rotating housing with the leading shoe was very, very unlikely. These days we use disk brakes which have calipers that squeeze the rotor faces to exchange momentum for heat (the heat of your brakes is the thermal equivalent of the energy it took to accelerate the vehicle (minus losses in the tire flex, wind resistance, etc)). And incase anyone is wondering, yes they are supposed to touch and drag a little with no pressure, its called lapping. As long as there is even wear on the pads, you're fine. A little one side or the other is okay, but it should be straight, not at an angle. If it is, lube your guide pins. Some wear on the rotor is fine. Dont let shops rip you off by showing you a normal worn in rotor and telling you it needs replacing. Long as its relatively uniform, and has more meat than the tolerance cast into the rotors inner rim, its fine. Tell them to piss off, and knock 20% off the bill for thinking you were dumb enough to fall for that, or youll call your cousin that works for NBC in the Dateline office (have you seen how small they make cameras these days? Its astounding....)

[@BananaGearStudios]

Interesting, I didn't know that.

[@RainDownpours]

What? Only 5.8k views? No way! You deserve more views.

[@BananaGearStudios]

Thank you!

[@RC.Bricks]

I was just thinking about a Lego rpm tester earlier, I was thinking of the first mechanism, I don’t think I could make this, but it’s really cool!

[@BananaGearStudios]

Thank you!

[@froodlenoodle]

this is awesome and explained so well

[@BananaGearStudios]

Thank you so much!

[@austinreed5191]

Great video! One critique: Every time you sped up the video, I would have preferred normal speed or even least slow-motion. Your finished mechanism working is like ASMR. You rushed through the best parts of your video.

[@CompoundBoy]

The existence og the Schmidt coupling blew my mind.

[@BananaGearStudios]

It certainly is very cool. I don't end up using it that often because it tends to take up quite a lot of space relative to the amount of travel it has, but when the right situation presents itself I'm always excited to use it.

[@BrunoAmaralBorges]

Came for the Lego's, stayed for the engineering class. Calculus is useful after all...

[@Scar32]

here is some steps for quick and accurate speed calibration for the pendulum 1. get an upper and lower bound, so get the length of the pendulum when it's too fast and when it's too slow, 2. average the upper and lower bound ((upper + lower) / 2) so that you get the middle and set the length to that 3. if it is too fast change the middle bound to be the new upper bound and if it's to slow then make it the lower bound 4. repeat at step 2 until you get the accuracy you need you can also average results to get more accurate measurements (measurement-1 + measurement-2 +measurement-3... / [how many measurements you have done])

[@drdca8263]

This is binary search, right?

[@Scar32]

@@drdca8263 it is sorta the same concept as binary search

[@delphicdescant]

Really cool machine. I'm almost tempted to go look at the price of some sets of this stuff, but I have to remind myself it's going to be like 4X what I expect.

[@PP4E]

Nice, how long did it take you to build it in real time?

[@BananaGearStudios]

Thanks, it took about 3 weeks to get it all working.

[@PP4E]

@@BananaGearStudios 🤩 wow

[@msk6003]

Very interesting

[@BananaGearStudios]

Thank you!

[@furriesinouterspaceUnited]

Amazing content

[@kubanek0958]

It is amazing❤

[@BananaGearStudios]

Thank you!

[@jakesteampson7043]

Inb4 you build a Lego replica of an early 1900's Hasler Geschwindigkeitsmesser

[@1e1001]

i'm surprsed you didn't just wire up the time axis to a consistent speed source, makes the graph easier to read and removes your aliasing issues, i guess only issue is figuring out how to get a consistent speed without a motor

[@Josh.Davidson]

Instant subscribe.

[@tiagotiagot]

If you turn the graph 45 degrees, and tune the scaling of the rotations axis so that it it has one rotation per time unit, would it become a speed graph instead of distance graph?

[@BananaGearStudios]

Nice idea, but sadly not. Firstly, if the motor was stationary then it wouldn't plot zero speed. But the main issue with using something like this machine for plotting speed rather than distance is that when the motor stops you'd need the graph to return to zero, which means it can't be driven just by the motion of the motor. I think your idea of rotating the graph would plot something like distance minus time, rather than distance divided by time.

[@antonagapov5087]

next - analog differentiation?

[@boldituzvillam2318]

Ok, so i might have missed something in the video, but i have a question. Why not just have two motors for x and y? This way, there won't be any bumps. I think that this was made too complicated. I know that this is supposed to measure using time, but why not have the timing module be connected to a motor that will only be on if the timer is well, timing. Please someone respond to me.

[@BananaGearStudios]

Thanks for the question. Firstly, I've found that the motors, at least with Power Functions battery boxes, aren't very consistent with their speed. After running motors on fresh batteries for just 5-10 minutes in previous videos I've found that already they've gotten a decent amount slower. So using the motor speed to show the flow of time just wouldn't be accurate enough, especially given the lengths I went to to try and make this as accurate as possible. Secondly, in this video I was measuring the speed of motors, but technically I could use it to measure the speed of anything, electrical or not. A big motivation for me making this video was to make a speed measurer that didn't use electronics for the measurements, otherwise I could've just used a tachometer. So I didn't want to rely on an electrical motor as part of the measuring process.

[@boldituzvillam2318]

​@@BananaGearStudiosoh ok. Thanks for replying! I don't know anything about Lego technic, but I saw in your reply, that you used Power functions battery boxes to power the motor. I don't know anything about Lego, so this might be the only battery box that functions with Lego motors, but if it isn't the only one, why not just use another battery box? I might have missed again something in your comment, but if you can answer this question, then I'll be happy. Thanks again for your reply!

[@MBF-ez1lo]

That is crazy

[@jeffcampsall5435]

Impressed 👍 Until you added calculus 🤪

[@jelletje8]

Awesome

[@FennecMizar]

One super minor thing that bugged me was the pendulum arm not having a counterweight added from that small extension for the grabber, i know it makes little to no difference but it still bugs me for some reason

[@FennecMizar]

I should mention that i am aware that so many other parts contribute significantly more to inconsistencies (like gear play and lack of lubrication considering the material) but the obvious visual difference did something to my adhd ridden brain

[@BananaGearStudios]

Yeah, I felt the same way a bit seeing the pendulum be asymmetrical after I added the hook to the side. I would've liked the mechanism to be able to hold the pendulum directly, without the need for a hook, but that would've made the mechanism a lot more complex. And I guess I could've added a counterweight, but my table not being 100% level probably made more of a difference :)

[@whattheheckisthisthing]

Why not just gear up the gravity governor?

[@Pystro]

[edit: Sorry, I misunderstood the question. For some reason I assumed that you were talking about increasing the gearing between the weight and the escapement gear. I'm keeping the below answer here for archival reasons, even though it has nothing to do with the actual question.] I guess the reason is, as he said in the video, that the pendulum and weight have to act on the various stopping mechanisms (and also overcome the pencil friction, tough with help from the pencil holder sliding down). You _could_ probably engineer a system where the weight only has to do one thing: release another weight. And then that second weight would act on the stopping mechanisms. But A: It's more effort, and B: The measuring time of 10 seconds is plenty enough time to build suspense for the result during a youtube video.

[@BananaGearStudios]

The main issue I had with it was that it wasn't accurate enough because the weights can just swing out freely, meaning they're easily affected by any small disturbances and/or friction. Gearing it up would've helped a bit, but it would still be an issue, and I definitely don't think it woud've had enough torque to draw the graph.

[@carternotsteve2242]

That would be a timed clutch.

[@NmpPnm]

Handcrank it ok❓

[@JOAOPROGAMER00]

30 Dias aprendendo basquete. Ate ficar bom

[@TheGibberingGoblin]

Bump

[@shavono8402]

14:20 That's not a problem that's a feature! You're taking the definite integral of the motor's speed over the sampling interval! This way, you can use it to literally just measure the actual speed of the motor over that time period, or you could use it to see how _far_ the motor has traveled (position), which is the integral of the motor's velocity. Very clever, even if that's not what you intended to use it for. edit: 20:25 lol

[@SquintyGears]

Nope, don't bring up analog sampling please. The fact that the measurements sometimes get graphed as bars is already stupid. Everything else in the video is flawless and really impressive. But Analog sampling is inherently a point system, not something you normally do derivatives on (exceptions exist but they're by definition the exceptions). Here you get away with it only because it's motion, speed, acceleration. But it's not true at all for other analog sampling. It's a common misconception that really grinds my gears.

[@ChristianFonsecaOFFICIAL]

1000 like

[@NmpPnm]

Handcrank it.

[@nexa4524]

20:31 - 20:41,Didn't get it, pls explain.

[@BananaGearStudios]

Thanks for the comment. The graph is showing the distance that the motor moves against time. Since speed is calculated as distance divided by time, the speed of the motor is shown by the gradient (slope) of the graph. What I explained was how you could approximately calculate the gradient of the graph at many different points over the 10 second sampling time - if you plot this gradient against time it gives you a graph of the motor's speed. Hope that helps.

[@nexa4524]

@@BananaGearStudios Thanks for replying.Yes, it definitely helped me, I was not the getting the plotting of gradient.