If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Spider's wheels

Created by Karl Wendt.

Want to join the conversation?

Video transcript

OK. So in this video, we're going to show you how to attach the bottle caps or the wheels and the tires, or the O rings. Now the wheels already have some small 1/16 inch holes drilled in them, but the holes are just a little bit too small. So we're going to take our screwdriver and make them just slightly a little bit bigger. It's really important that you don't make the holes too much bigger because if you do, they'll be sloppy and they won't fit snugly on the axles. So we're going to push those on. And it should be pretty tough to push on. You want to really give them a little bit of a shove there. Now, one thing I want to point out, in this video, I did things somewhat out of order. It's important to put the O rings on the bottle caps before you connect them. In this video, I put the O rings on afterwards. And it's just a lot more work to do it that way. It's a lot harder to get them on. So put the O rings on first, then put the wheels on, and you'll see how we connect the O rings in just a second. OK. So what I'm doing here is I'm just trying to make sure that wheel spins true. So you can see that as I turn it, it sort of wobbles. And you want to keep adjusting it until it's almost perfectly smooth. And then you want to do the same to the other side. You'll put the wheel on, the bottle cap on, you'll push it down, and once it's in place, you're going to turn it and make sure that it spins very smooth and true and doesn't wobble. Once you've got that, you can take it and turn it on an angle. And you're going to take your hot glue gun and you're going to put about a dime-sized blob of hot glue right on the center of the axle. And you'll hold that perfectly up and down until the hot glue dries. And then you'll do the same thing to the other side. Make sure you don't flip the bot around until the hot glue is completely dry. It'll take about two or three minutes. And the hot glue should turn from clear to milky. Now we're going to connect the O rings or the tires to our bottle caps. Now like I said earlier, it's a lot easier to connect these O rings to the bottle caps before you attach the bottle caps to the axles. So don't do it the way that I'm doing here. But in any case, what you do is just-- in this case, I'm checking to make sure that the hot glue is completely dry. And then trying to stretch the O ring around the bottle cap. And it's a really tight fit and that's actually a good thing. It means that our tires aren't going to slip around. And they should provide some good grip for us. So once we've got the O ring on, you can see it's kind of tricky to get on especially with it mounted in place. If it's on the table, it's a lot easier to get on because you can push down on the table really hard. OK. So that's good. So we have one tire in place. And then we'll attach the other tire in the exact same way. Make sure everything is true and straight. Get the second tire put on. We'll run the bot back and forth on the table to make sure that it is running smoothly and nothing is rubbing up against the wheels. And it should move very smoothly, and we'll be ready for our next step.