(energetic music)

Hello and welcome to the first Engineering 101 live session. My name is Matt, and just a little bit of background before we get into it, I studied and graduated from Robert Morris University with a degree in mechanical engineering. So I love all things mechanical, and the purpose of today's live session and all moving forward Engineering 101 live sessions is that I basically want to introduce the engineering concepts that are found within your VEX system kits.

I wanna introduce those concepts and just kind of explore them just for those of you who may not realize what they are, where they are, how you can introduce them, how you can teach with them, or for those of you who wanna see something more that you can do with your VEX kits. Mainly today, we will be looking at the VEX IQ robots, but rest assured, these concepts can apply to pretty much all of the VEX, different VEX systems, so from 123 all the way up to V5. I'll go through just kind of how those can apply once we get there, but for the most part, today's live session, we will be focusing on gears and the mechanical advantage behind them.

We'll be covering all the different math that goes into these gears, how you know when to apply these gears basically whenever you come to a build and you think to yourself, hmm, it's not doing exactly what I want it to do, so how can I improve it? Well, basically, the purpose of today's live session is to introduce the tool to you that gears are really, really cool to use and just you can apply them really anywhere once we learn the practicality of the mechanics behind them.

So yeah, if you have any prompts for these Engineering 101 courses or if there's anything you would like to see, please comment it in the PD+ community, the Engineering 101 thread, I'll be monitoring that and updating y'all with cool things that I find that we may cover in the future. So without further ado, let's jump on into today's live session.

Now, as I said, this is the Engineering 101, the first live session that we will be covering, in which we will be looking at gears. So if I'm new to VEX, what is the need for gears? Well, the really, really cool thing about gears is that they are basically found in any mechanism in the 21st century that involves motion. Gears allow for the transfer of power through mechanical advantage.

Now, if you may be like me in my freshman year of college, what is mechanical advantage? Well, mechanical advantage, I'm gonna write it, oh, that's way out of camera, I'm gonna write it as MA or mechanical advantage is the relationship of the amount of force that you are putting into a system, that variable is underneath the force that you are getting out of a system. So Fi for force in, which is underneath Fo or force out. So mechanical advantage basically is talking about how many jelly beans you're getting out versus how many jelly beans you're getting in.

This can be visualized with a simple gear train just like this. Now, with this gear, once I see that the force that I am applying to this first gear, I can see that that second gear is moving a lot faster, right, where you can tell through the holes of those gears, I can see that that smaller gear is spinning a lot faster than how I am spinning the bigger gear. So mechanical advantage denotes the difference between what you're putting in versus what you're getting out. And what's amazing about the gears is that they do this seamlessly.

So if you were ever looking at an old bicycle, those penny-farthing bicycles, and you're wondering, why do they have one big tire? Well, that's not just for show, you know, like a unicycle and riding something cool like that. It's actually because gears were not as explored back in the day whenever these bicycles were being made.

Thank you for joining today's session. I hope you found it informative and engaging. Please feel free to reach out with any questions or suggestions for future topics. Looking forward to seeing you in the next session!

If you had a bicycle without any gears, two similar-sized wheels would be very difficult to manage and would require a lot of force to get the desired output. A really cool engineering solution for this was to design a bicycle with one big front tire and a smaller rear tire. The benefit of using a big tire is that it increases the distance from the center of rotation, which, in turn, increases the torque. But that's a whole different story for another time. It just goes to show that without gears, you'll need some pretty fancy flying to accomplish your goals.

With the use of gears, you may be more familiar with bikes that have different gear trains. You can gear up to climb a hill quickly or gear down if you're going very fast. The usage of gears allows you to move things faster and lift heavier loads. Otherwise, as mentioned, you'd have to do some pretty fancy flying to navigate obstacles.

Now, as we just covered, there are basically two main purposes of gears: to either increase torque or increase speed. Let me get our demonstration up. The law of conservation of energy states that energy can neither be created nor destroyed. Using our gears, I can see that when I turn my smaller gear slowly, my bigger gear is not moving as fast as the smaller gear. Since energy can neither be created nor destroyed, that rotational speed has to go somewhere, and it is generated through torque.

Whenever you are using gears, this is either through torque or speed. If we did the opposite and spun our larger gear, no matter how we spin it, the smaller gear moves much faster. These relationships can be determined through our gear ratio formula, which you may be familiar with. We can also calculate the rotation through our gear ratio. This is really helpful when you have an assembly and want a different outcome. You can apply this equation to your build before you start.

Let's see what this looks like. I have a MAD Box in front of us. This is from a very old curriculum in the VEX IQ system, but it perfectly highlights the difference between gear ratios, gearing up, and gearing down. When I spin the handle, which turns a 12-tooth gear interacting with a 36-tooth gear, and it's on the same shaft as another 12-tooth gear, no matter how fast I spin the 12-tooth gear, the output handle at the top moves slowly. This is cool because we are converting speed into torque.

If you had a robot that wasn't pushing or lifting as much power, this concept is useful because it increases the output from your motor through mechanical advantage. Once we increase the torque, the torque energy is much higher than before through the different gears. On the opposite side, if we spin the other gear, you'll notice that the smaller handle attached to the 12-tooth gear spins much faster than when we were spinning the 12-tooth gear before.

Thank you for your attention, and I hope this demonstration has been informative. If you have any questions, feel free to ask.

Thank you once again for joining us today. We appreciate your time and interest.

Now, this is really cool as, again, if we recall our two equations that we have, both the gear ratio equation as well as that rotational equation, we can calculate what we are going to see. So basically, we can calculate beforehand and see if our results line up with that math. This is something that's really, really cool to do, really cool to see in class as well as apply it with your VEX IQ gears, with your VEX GO gears, EXP gears, just to see how these boxes and how these gears actually interact with each other to convert our speed here.

So basically, if you had your motor attached here, it's converting that motor power into speed at the sake of torque. It's a really, really cool concept; whenever you are going from one to another, you're sacrificing the other. Okay, let's take a look at the math behind that MAD Box. Again, this can be applied to any concept and any time you want to apply or you want your robot to do something, you can apply the usage of gears.

What that formula says is that the number of the rotation of the input gear multiplied with the teeth of the input gear is equal to the rotation of the output gear times the number of teeth of the output gear. Before we jump into this pretty complex example that utilizes gears on gears using the same shafts, let's just take a quick look at this example, so back to our 60-tooth gear and our 12-tooth gear.

If we were to spin our 60-tooth gear at 10 spins per minute or 10 rotations per minute, let's go ahead and write that, so 10 rpm. Now, again, our number of teeth for this gear is 60. We are not sure of what that output will be just yet for that 12-tooth gear, so we can go ahead and keep that as our variable that we are searching for. We know that the number of teeth for that 12-tooth gear is 12. With some simple rearranging, we can find that the rotation of our output will be equal to the rotation of the 60-tooth gear over the number of teeth of that smaller driven gear. Remember the difference between the driving versus driven. The driving gear is always what gear is directly attached to your power. Your power may be your motor, it may be just your hand that you're spinning. The driving gear is that input gear. Our output gear or our driven gear is basically simply remembered as driven by the driving gear.

Once we have all that, we can simply plug it into our calculator and we can see that we can easily calculate the speed at which our 12-tooth gear will spin at even before we go ahead and build this contraption. Basically, just by following along with this math and doing 10 times 60, giving us 600 divided by 12, 600 divided by 12 is 50. Remember our conversions, so these teeth will both cancel out with each other, leaving us with rpm. We know that if we spin this 60-tooth gear at 10 rotations per minute, our driven gear, excuse me, the 12-tooth gear, will spin at 50 rotations per minute.

This is, again, very, very, very helpful for us whenever we have our robot that may not be functioning how we want it to, say our wheels are only turning at a slow speed of five rotations per minute. I can go ahead and just work out with the different numbers of teeth, of gears in my kit. With those, I can kind of guess, with all the math, just to see, okay, I want it to go faster, thus I am going to go from a big gear to a small gear. So yeah. These math equations are very, very helpful for me, again, basically with those use cases that, whenever I know that I want a different outcome from what I have, I can go ahead before I actually build it and see what that will come out to.

The other way that you can do this is with the gear ratios, so we have found the direct rotation of what our gears will be, but how can we find out the amount of rotations it takes for our 60-tooth gear that will be affected by our 12-tooth gear?

Because those teeth are perfectly interlacing with one another, I know that one gear is going to have to spin a lot faster than the other gear. To do this, we can use that top equation, just this one, this top equation. That gear ratio is equal to the driven gear or the output over the driving gear. Using our same example of this 60-tooth gear driving that 12-tooth gear, we can determine our gear ratio to be the driven, which is that 12-tooth gear, over the driving, which is the 60-tooth gear. 12 over 60. That should be the one to five gear ratio because we will now notice, for every one rotation of our 60-tooth gear, that will result in five rotations of our smaller gear.

A combination of both of these two equations is really, really helpful and useful whenever it comes to going a step further with these gears in your kits and applying the real-life principles behind them. Very helpful whenever it comes to, just before the build, seeing what you can do.

Now, back to our MAD Box example. We know that, if we were to spin this first 12-tooth gear at a pretty hefty speed of 50 rotations per minute, we can see that that 36-tooth gear is going a lot slower. I've already gone ahead and did the math for this one. If we were to spin that 12-tooth gear at a speed of 50 rotations per minute, that 36-tooth gear would be going at 16 rotations per minute. So from going from smaller to a bigger gear, we're increasing that torque. Torque is basically how much energy it takes to do that rotation, so the higher the torque, that means the stronger your build is.

With this torqued-up MAD Box, you can see that I can still spin that smaller gear a lot easier, and it is very, very difficult to try and stop that top handle. On the other hand, if I were to spin that 36-tooth gear, that 12-tooth gear spins a lot faster through this system, converting that speed or converting that torque into speed. That's basically the rundown of how the gears work. They are able to intermesh with one another in the VEX system as well as in real life once you align your gears properly.

Now, that's the next hardest thing whenever it comes to applying these gears, is just making sure that your gears are perfectly aligned. As I can see, our 60-tooth gear is going to take up a pretty hefty distance on our plate. If we were to put that dead center, I can see that I now have one, two, three empty holes until I have an empty hole in our beam again. If I were to take a 12-tooth gear and put it directly on the outside of that gear, it's pretty easy to get them to mesh up. But whenever it comes to trying to line up bigger gears, it may get difficult just trying to see where the perfect spot is.

As you can see here, I placed another 60-tooth gear in, but they are just ever so slightly out of whack. If I were to turn the first 60-tooth gear, it's not gonna be directly turning that second one. It's very, very important whenever you are actually building just to make sure that your gears are aligning. Once they align and they're on the same row and same column as each other, they'll align pretty easily, you can see that. That's basically how you get them to intermesh. Again, that's very, very important whenever you want to begin building, and that may be the difficult version. To find out how, just put it around your build and see where it goes.

You'll notice I tried to put our 12-tooth gear pretty close to a 60-tooth gear and it's turning very harshly, it takes a lot more force than it should. Once you get it in the correct location, you'll know because it'll spin a lot more easily. Again, back to the main purposes of gears, it's either to increase the torque or increase the speed. Now, applying this basically means whatever your robot is doing, how can you make it better?

Thank you for your attention and interest in learning about gear systems. I hope this information helps you in your future projects and builds. If you have any questions or need further clarification, feel free to reach out. Happy building!

If you want your robot to go faster or if you found that your robot is moving too fast, you can use gears to slow your robot down. There was a phenomenal PD+ post about this, that the gears were moving too fast for the robot to be controllable. So a solution that we have found was actually to use the gear train. You want to use a bigger gear to drive a smaller gear, thus in turn reducing the speed, at the same time increasing the torque.

It's a hand-in-hand relationship that, with gears, you're transferring that energy. If you're transferring it into speed, you're gonna lose torque, but if you're transferring the speed to go slower, you're gonna gain torque, which will make your robot stronger. Gears are perfect, and we can see them actually in use in a lot of the builds found on builds.vex.com. Just for lifting, as we can see on the Clawbot, we have those 12-tooth gears driving those 36-tooth gears in order to generate torque to lift our arm.

It's very, very cool, at least to me, to study and see how these gears are functioning with one another and basically calculate beforehand before you come to build. So yeah, we covered how you can do the math beforehand with the gear ratios, finding out the different rotation speeds beforehand. If you know that your robot's going too fast, you wanna slow your robot down, but you're unsure how to do so in code, well, fear not code, you can do it in your physical build. So again, you can use those different gear ratios to either increase speed or whatever you want.

Now, actually applying these gears, it is found throughout many of the different STEM Labs, just for a couple of examples, it's in the IQ second gen Tug of War STEM Lab. It's found in pretty much all of the VIQC, VRC games, whether that be shooting for your flywheel to shoot discs for or stuff of that matter. We can see that this is found actually on the Hero Bot for the VIQC 2022-23 Slapshot. It uses a bunch of different gears, again, to both increase the power, so with the mechanical advantage, we're increasing that power, our force in is now lower than that force out, so our mechanical advantage is a lot higher, meaning it is now stronger with that.

And yeah, it's basically found on a lot of the builds at builds.vex.com, so we have it on our Clawbot, we have it on our Hero Bots. One of my favorite is that it's found in the build instructions of the Motorized Super Car for GO. So with that Motorized Super Car, it uses two different gears on the outside. We can see that, once we are going from a smaller gear to that bigger gear, that smaller gear will have to spin more in order to turn that bigger gear. So remember those gear ratios, we're gonna have a lower, like five to one gear ratio for that. Or going from different, in this example, there would be no mechanical advantage because those two gears are the same size. That gear ratio is one to one.

Same here, now the gear ratio and the mechanical advantage will be lower because the force out, the torque that we're getting, is now lower due to the higher speed. So again, once that speed goes up from your motors, the torque will then go down because, again, of that conservation of energy, mass, energy cannot be created nor destroyed. So it only can be transferred to other means, aka that torque or that speed.

So yeah, as we went through, we found those different claws. We noticed all of our claws have these gears. Gears are just a phenomenal way and a great tool that it comes to applying the different mechanical advantages. We can see that they are in claws, they're in our lifting assemblies. Gears can be used anywhere that you feel the need that mechanical advantage is important or you want to do something different.

So again, with our application of these gears, they can be done anywhere that you feel you would require a stronger kind of movement.

So we've already covered how the gears mesh and all of that. Let's actually go over how one would go about applying these gears. In the IQ STEM Lab Tug of War, the main goal was to try and pull your opponent. How can you do this with gears? Well, basically, you can do that pretty simply by adding just a quick little gear train.

From our motors, I'm just gonna do this pretty quickly. We can just change out the shaft in order to minimize interference. Just gonna pull this off so I can access that shaft. What's great is that, once you change this shaft, bear with me, once we have that smaller shaft in there, let's go ahead and put it back on our build, slide it right through. This is just how fast these gears can be applied and changed. It's really, really cool. Move this one up one more. Okay. Just like that.

What we can do is do a gear increase so our driving gear or the input from our motor will be spinning at a slower speed as compared to our driven gear or the outward gear. To do this, I'm gonna grab just one of our gears. Let's actually open this up so you can see it a little better. Whenever we put this on to our robot, this is our driving shaft and this will be our driven gear, which will now be directly applied to our wheel. By doing this, we have that smaller gear will now spin more relative to that bigger gear, thus increasing the torque or the force from that motor. Once we have that on, we can basically put our cover back over.

Again, this is just a simple demonstration to show how gears can be used pretty quickly, pretty cheaply, and in a very small area. Now here's actually a great demonstration to do this. The brain will light up pretty much from the amount of force that's going into the brain whenever it's turned off. With our motor that we did not do anything to, just that straight gear to that wheel, you can see that that light isn't really coming on no matter how fast I turn just the wheel going straight into that motor. Now, with our increased gear train, I can spin that wheel and that light comes on a lot more reliably, more fast. That's just going from that gear increase, from that 12-tooth gear to that 36-tooth gear. Remember, we did that math from that gear up, we determined how you can find those rotations.

Yeah, that's how these gears can actually be applied. You can do this in any concept if you need your robot to move faster. If your robot's moving too fast, you can gear your robot down. If your robot may be moving too slowly or it's too weak, too strong, gears will be your best friend. Basically, I just wanted to stress that, that the gears are your best friends.

Now, gears, sprockets, and pulleys all have kind of a similar function, but just different use cases. They have similar operations where one will spin slower or faster than the other. We have that with different chains, different pulleys. We can actually see an example of this on the Hero Bot Slapshot. Our sprocket system, as you've noticed, it's falling apart because sprockets now have to rely on the individual connection points between those chains. The difference between using either a gear or a sprocket, with the sprockets, it might be a little bit more weak as opposed to just using a straight gear train. The benefit to using the sprockets is that you're able to transfer power over a greater distance without having to use 10 different gears. Chains are really cool if you need to save on space.

Additionally, they're very, very similar to pulleys. Now, pulleys, the only thing with them is that they may slip. If you notice in that image, there's nothing holding that pulley to our build other than friction, so the more force you put on, again, it may slip. They're very, very similar function-wise in order to increase that mechanical advantage that we're talking about.

But they have those different use cases, so it's very, very interesting whenever it comes to applying these gears, seeing how there is very distinctive math behind them in order to calculate beforehand how you can either increase that speed or increase that torque. Now, again, you can apply it anywhere that you have a robot that you need it to do one of the either increase speed or increase torque.

I hope you're able to use some of the different math in order to do so. Again, feel free to comment and post at me in the PD+ community whenever it comes to applying the different gears. It's really, really cool and it's really interesting in order to use that math. It's one of my favorite things to do, is to kind of go behind the scenes and understand what is actually going about here, so being able to see that math happen and then able to put it into practice with your gears and understanding that, oh, if I use a smaller gear into a bigger gear, it will make my wheel turn slowly and it will increase that power delivered to that wheel.

You can combine many different gears and have idling gears, stacked gears, and all different types of gear trains. I hope you've enjoyed our first live session for today, our gear pretty much palooza in which we've covered all the different gears. If you have any questions, please post in the PD+ community about these gears. Again, they're really, really interesting and they can be applied anywhere.

I hope today's lesson has taken out the kind of worrying about where you can apply gear trains and all that and how math is involved. It's really interesting and yeah. If you have any questions, please let me know, feel free to shoot them in the chat and yeah, we can go from there and they're really, really interesting, being able to apply these different gears. Please feel free to post me in the PD+ community. And yeah, they're really, really cool just to see what they can do, so. They're one of my favorite, going through college and being able to see what can be done. Being able to apply them with your robot builds, it's a really cool thing to do. So yeah.

Again, as I said, I love doing the math, so being able to see that math in the foreground. So yeah, we'll leave in a minute. If there's any questions, we can cover more in depth about the gears. If not, we can always post them in PD+, we can keep that thread active. Yeah. Those two different equations are really, really cool in order to really just understand what's going on behind the scenes. So yeah, being able to realize something deeper is really happening and being able to kind of examine that further. That's what I like to do with it at least, is that they look like really simple things, but there's a lot going on behind them, you know, with all the different mechanisms and laws of energy and whatnot.

That energy one is the coolest to me, how energy can neither be created nor destroyed, only transferred. So if it's not going to your build, it may be coming out through other means such as heat. If you have a drive train that may be not functioning most efficiently, if you feel your plastic and it's a little warm, that power transfer may be getting transferred through friction in your build generating heat, that is that energy not being created nor destroyed.

Hey, Matt. Yeah. It's Lauren. I have one question.

Yeah, of course.

Is there a way, from the devices screen, I saw what you were doing earlier on your Clawbot there with the gear train on one side and the not the gear train on the other. Is there a way to see information about the motors from that particular screen if I wanted to?

Yeah, yeah, you're definitely able to. So we can go through and kind of put on our devices screen, so with that top down, that claw is in the way so it's a little hard to see.

So as we can see, it says our velocity is the 50 rotations per minute, but we can notice that our bigger gear is moving a lot slower. Now we can go ahead and turn that off. Now we can go to our second motor and we can see that the same command is now making it go a lot faster. Being able to use the devices menu to control those motors, it's really cool to see how it functions and how you can get that information through that screen.

I also have a controller here. You can pair the controller and see the different speeds that will be output by our two motors. Now that we're paired, you can go in and see that our wheels are now moving a lot differently, so I have to control them a lot differently just with our controllers. I have to input one motor at a higher speed, higher threshold, in order to get them to turn.

Another cool thing to realize is the two different rotations with the gears. You'll notice that whenever I put my left joystick forward, it actually moves our robot in reverse. Likewise, if I put that right joystick forward, it moves that side forward. Now, with the two different gears that we have on, if I just pop this off really quickly, our teeth will bite with one another. For our rotation of this first gear, it will make that second gear rotate in the opposite direction. It's really, really cool when you are applying these gears to take note of the different things that will be happening. If you are increasing that speed or increasing that torque, you might need to take into account those different rotations. It's really, really cool with the amount of stuff that you can do with gears.

Great. Thanks, Matt, I just wanted to let you know there weren't any other questions in the chat, but thanks for showing that.

All right, perfect. If anybody else has any further questions, I implore you to post in the PD+ community, the Engineering 101 thread. I can go through and share the slideshow, share the instructions to that MAD Box so you can build it and try it out yourself to see the difference in the speed and torque. Again, if there are any other questions, please feel free to ping me there, and I'll be happy to answer them.

I hope you enjoyed the Engineering 101 session on our gears and the mechanical advantages behind them. I look forward to seeing you in the next one. If there's anything I can do, please feel free to reach out to me. I have my information up here, and I'm also in PD+. Thank you all for coming.

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