Ben Eater's Spider

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About this video

Ben adapts a kit bot by replacing the popsicle sticks with cut circuit board and using clips to hold the batteries, so they can be swapped without re-gluing. He balances the bot by adjusting the battery position, and backs the bottle caps off the knurled part of the motor shaft for more grip.

You'll be able to

  • explain why removable battery clips make a build easier to change
  • balance a bot by adjusting part positions
  • explain how positioning a cap on a textured shaft improves grip

Key words

Battery clip
A holder that lets a battery snap in and out without glue.
Knurled shaft
A motor shaft with a textured, ridged surface that gives friction to a part pushed onto it.
Friction
The resistance between two surfaces in contact that stops them slipping.
Balance
Even weight distribution so the bot rocks or wobbles less.
Transcript

- [Interviewer] So I see you've done something different with the bot.

- [Ben] Yeah, so you gave me this kit to just kind of try it out, to test out, and a couple of things that I did a little bit differently. One is, the kit you gave me didn't have popsicle sticks, so I was just sort of rummaging around to see what I had, and I had some printed circuit board, so I just kinda cut those out.

So you can use- - [Interviewer] Oh, that's cool.

- [Ben] You can just kinda use whatever you have, and the other thing you notice, when I was looking for something to replace the popsicle sticks, I found these little clips, that you can use to clip the batteries in.

- [Interviewer] Oh, that's great! And then you don't have to worry about, like, breaking the hot glue and redoing it, you can just sort of snap 'em on.

- [Ben] Yeah, the battery just pops out like that.

- [Interviewer] You take the battery, oh yeah, that's awesome.

- [Ben] Battery comes right out, you can pop it back in, and this is actually good, 'cause I didn't have any batteries at home that weren't dead, so I didn't wanna glue the dead ones in.

- [Interviewer] Yeah, that makes it a lot easier to swap out. I notice you don't have a paper clip on that one. [Ben] Yeah, the other nice thing about this, and I totally didn't intend this, but, you know, the paperclip kinda keeps it from rocking back and forth like this?

- [Interviewer] Yeah. - [Ben] You can see it's kind of rocking, but if you, I found if you just back these batteries out a little bit, they have the same effect.

- [Interviewer] Oh, that's awesome, yeah.

- [Ben] So now it doesn't rock quite as much.

- [Interviewer] So you can get it to- - [Ben] So you can just kind of, you know, adjust these one way or the other and get the balance just right.

- [Interviewer] Yeah, that's awesome. Can we see it run?

- [Ben] Yeah, yeah, I got a little program in here that makes 'em spin. (robot whirs and hums)

- [Interviewer] Oh, there it goes, nice. - [Ben] There it goes, it just goes back and forth.

- [Interviewer] Oh, I like that, that's awesome. I like the way that you changed out the batteries. (robot whirs) You have to grab him at just the right time!

- [Ben] Yep. (laughing) - [Interviewer] Got it. (robot whirs) Oh that is, that's really great. I mean, that makes it a whole lot easier to upgrade and change those things out.

- [Ben] Yeah, it's much easier than having to pry off the hot glue and re-glue the batteries, 'cause batteries are such a, kind of an integral part of the structure, right?

- [Interviewer] Yeah, yeah yeah, and that's a nice improvisation there with the circuit board, I guess you could use just about anything that's consistently, a consistent thickness and what have you.

- [Ben] Yeah, just rummaging around for something stiff like that, that's what I came across.

- [Interviewer] I notice one more thing on yours, the bottle caps aren't quite flush against the motor? Can you explain why you did it that way?

- [Ben] Yeah, something I noticed, you didn't call this out in the video, but just as I was putting it together, I don't know if you can kind of see, yeah the bottle caps don't go all the way back, and that's just because, if you look at the shaft of the motor, I don't know if you have another motor around here somewhere.

- [Interviewer] Sure, yeah, let me see if I can dig one-

- [Ben] But the shaft of that motor is kinda knurled towards the end, but not all the way in, and so I didn't wanna put the bottle cap all the way in. If you look at the motor here, you can kinda see this, this textured area area.

- [Interviewer] Oh yeah, yeah. - [Ben] So I just kinda backed the bottle cap out a little bit so that it's against that textured area, so that there's a little bit more friction between the motor shaft and the bottle cap.

- [Interviewer] Oh that's great, yeah, so that way you don't have to worry about it slipping and coming loose as much.

- [Ben] That's right. - [Interviewer] Cool, awesome. Well, Ben, that looks great.

- [Ben] Yeah, it was a fun little project.

- [Interviewer] Cool. - [Ben] Thanks for using me as a guinea pig.

- [Interviewer] (laughing)

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