Introduction: LET'S MAKE a BRUSHBOT
Brushbots are a great project for kids - and adults! We make them with kids from 4 years and up with very close supervision from very well trained staff. We like to use hot glue guns, which are really useful tools, but also a bit dangerous if not used correctly.
ALWAYS SUPERVISE CHILDREN IF USING TOOLS.
If you would prefer not to use glue guns you can also use sellotape and/or double sided sticky foam tape. Be careful out there!
A brushbot is a skittering, zooming robot that bounces off obstacles and behaves in a generally erratic and fun way! They are easy to build and can be made in all sorts of shapes and sizes. If you've made a doodlebot before you'll recognise some of the more important parts. We like to think that brushbots are not so distant relatives of doodlebots given some of their striking similarities.
LET'S GET ORGANISED
You can pick up some of the parts used in MAKESHOP if you happen to be in Dublin. We've also provided links to a couple of online suppliers.
- Small 3V hobby DC motor like this one or this one.
- A coin or cork or similar to use as a counterweight.
- 2X AA batteries
- 1X double AA battery holder like this one
- (OPTIONAL) Self adhesive motor adaptor like this. You can just attach the motor directly to the bot if you like.
- (OPTIONAL) Slide Switch like this one.
- Things to decorate with. Eg. pipe cleaners, googly eyes, coloured paper.
- Hot glue gun and glue. Can also use tape or double sided adhesive foam tape if you prefer
- Wire strippers
- Wire cutters
Be careful with these tools!
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Step 1: LET'S TEST THAT MOTOR ...
We're going to check our batteries and motor to make sure everything's working nicely.
- Strip a little insulation from the end of each of the wires coming from the battery pack. DO NOT CONNECT THE WIRES TO EACH OTHER
- Pop your batteries in. 1.5 Volts plus 1.5 Volts (in series) gives us 3 Volts. Our motors are meant to be used with 2.5 to 6 volts.
- Make a little hook in the end of one of the wires and hook it through one of the tabs on the back of the motor.
- Hook the other wire through the other tab. Touch the small bit poking out the front to see if it's spinning.
What would happen if you swapped the red (positive) and black (negative) wires?
Give it a try!
Step 2: LET'S MAKE THE SHAKE
Doodlebots and Brushbots share some anatomical features which indicate that they may be related. In particular the "shakey bit" (Latin: quod tremefacio) are used by both for locomotion.
We're going to start by building this part.
We've used a penny as the counterweight here. You could also use a bottle cap, a cork or any other similarly sized thing that you could glue onto the shaft of the motor.
- Squeeze a pea sized blob of glue onto the penny.
- Put a little glue on the end of the shaft of the motor and push the shaft of the motor into the blob of glue on the penny, off centre - about half way between the centre of the penny and the edge of the penny.
- Hold the motor for a minute while the glue sets.
Step 3: LET'S DECIDE WHERE THE BATTERY PACK GOES
Think about where you want the battery pack to go.
Remember that batteries are kind of heavy and you don't want the brushbot to fall over all the time ... or maybe you do. I don't know.
You also want to be able to get at the batteries to change them when they run out.
- Decide where to put the battery pack and put some glue there.
- Glue the battery pack in place.
- Double check how the brushbot balances; you might be able to use the motor to balance out the battery pack.
Step 4: LET'S FIGURE OUT WHERE TO PUT THE SHAKE
That shaky thing we made earlier ... we need to work out a good place to put it.
Since it's sort of heavy, we can use it to counteract the weight of the battery pack or place it so that the brushbot is just about balancing. This can make for a fast brushbot.
- I'm using a motor holder with a sticky pad on the bottom so I can try a couple of different places out. You can use tape instead.
- When you find a spot that works well, glue the motor there.
- The bottom two panels show a trick for turning your motor on and off without having to unhook a wire every time.
In the next step we'll show you how to add a switch if you have one and like the idea of adding switches to things.
Step 5: LET'S ADD a SWITCH
If you have a toggle or slide switch you could use it to turn your brushbot on and off.
- Decide where to put your slide switch. Cut one of the wires from the battery pack long enough to reach one of the tabs on the switch and strip some of the insulation from the end. The brushbot turns off!
- Hook the end of the wire from the battery pack through one of the tabs at the end of the switch.
- Hook the end of the piece connected to the motor through the middle tab nearest to the tab you just used.
- Once you are happy the switch is working, glue it in place.
A note on switches:
The switch we're using here is called a "Double Pole Double Throw" slide switch - or DPDT for short. If you look at the picture it has two rows of three tabs. Each of these rows of three tabs is actually one switch, but both switches are controlled by one lever. So a switch like this could control two separate circuits with the flick of one switch!
The middle tab in each row is connected to the "Pole". Depending on which way you slide the lever, the pole will either connect to the tab to its right or the tab to its left; Each of these is called a "Throw". So this switch has 2 poles (DP) and each of those has two throws (DT).
All we really need for this particular circuit is Single Pole and a Single Throw - SPST - and if you have one of those switches you would only have two tabs to connect the end of those wires to ... so just use those!
If your switch has three tabs it's a SPDT switch. Use the pole (middle tab) and either one of the throws (end tab).
The wonderful people at Sparkfun describe switches in more detail here.
Can you work out a way to use a DPDT switch to control whether the motor spins clockwise or anticlockwise?
Hint: Remember how you had to swap the wires from the battery to change the direction the motor spins.
Step 6: LET'S DECORATE THE BRUSHBOT
Maybe you're happy with a bare bones look, but if you want you can add some personality by decorating your brushbot.
You can let your imagination run wild at this point, but first let us give you some tips for gluing decorations on safely!
- Decide where on the brushbot to put a decoration. Put a pea sized blob of glue there, not on the decoration itself
- Count 15 seconds to let the glue cool a little - don't worry, it will still be sticky. Carefully press the decoration into the glue
- When you are gluing a small thing onto a bigger thing, always put glue on the bigger thing, wait, and then stick on the smaller thing
- Keep adding decorations like this until you are satisfied with the result ...
Well done! You've created a brushbot! Now you can try creating a flock of brushbots and figure out a way to herd them effectively - because we haven't yet.
Step 7: LET'S LOOK AT SOME OTHER TYPES
Here are some other brushbots we threw together to provide the one we just met with a little company.
We didn't have a switch handy for the top one, so we made a handy little hook for one of the wires from the battery pack using a paper clip. This makes it easier to turn it on and off.
By the time we got to the next one we didn't have any wire or a battery pack. We pulled some of the fuzz off the ends of two pipe cleaners so we could use them as wires. We had a couple of LR44 batteries and we made a battery clip from the packet they came in, and stacked them end to end in series, plus against minus. Connect the wires to each end of the stack (plus and minus) and you have a very speedy brushbot! DO NOT CONNECT THE WIRES TO EACH OTHER!
In the end the first brushbot we made wasn't really interested in socialising with the others. Sibling rivalry perhaps?
As you can see, they all move in different ways. In general, smaller or lighter brushbots are a bit faster. You can try to bend the bristles on the brush to get the brushbot to move in a particular direction. Experiment with where you put the shake and how you balance the brushbot.