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How to Build a Robot - The BeetleBot

Picture of How to Build a Robot - The BeetleBot

I have been in robotics since I was a kid and I am very passionate by robotics. I learn BEAM robotics around 1997-98 and started building robots for a science faire project call "Insectroides" in 2001. http://robomaniac.solarbotics.net ( they change server and the website links does not work anymore it is on Linux and it is CASE SeNsiTIve! ) here is the old one

One of my many robots was the beetle robot, a VERY simple robot that can avoid obstacles on the floor without ANY silicon chip! ( the red ladybug, second picture, is my FIRST beetlerobot )
the red ladybug use a home made PCB carve with a dremel and two playstation motors with rubber wheel from a walkman!


It use
2 - motors
2 - SPDT switch
1 - AA battery holder

I has 16 years old when my uncle showed me the principal of the SPDT switch ( Simple Pole Double Throw). I then took this idea and incorporated the design into the (world famous) beetle robot :P

Now I am 22 and want to show you step by step instructions how YOU can make this simple robot!

here are some videos of my beetlerobot in action!

The beetlerobot in the video is made using a Printed Circuit Board ( PCB ).
This design will be use if I make a kit one day!

Check them all out here!

This Instructable is divided into three parts

- You will learn how to build the robot
- I will explain how the robot works
- I will then teach you how to fix your robot if it does not work ( Debugging )

Don't forget to read the complete tutorial before starting! And remember to wear safety glasses at all time because eye injuries ain't worth the risk! It will happen in a blick of an eye.

Have a great time!

ps- Check out Gareth Branwyn book, I made a one motor walker and he made a complete chapter with my robot!! He send me the book call " Absolute beginner's guide to building robots" A very great book!

Maybe I should write a book...

Jerome Demers aka ROBOMANIAC!

Updated july 2007 - I have added some pictures of the inside of my first beetlerobot. Home made AAA battery holder! I have also added some videos on youtube! http://www.youtube.com/jeromedemers

Updated 22 july 2007 - I added a picture and text on step 19 if your robot does not work :P
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Step 1: All the parts you need

Picture of All the parts you need
around 22 gauge wire will do
1,5Volts motors
SPDT switchs Some that are EASY to trigger
wooden or plastic pearl
paper clip 2 small one for the antenna 1 big one for the back caster of the robot ( it can be a small one )
heatshrink to go over the motor shaft
a good quality AA battery holder
Here ar the parts you will need:

the robot parts'
2 - 1,5V motors
2 - SPDT switchs mechanically easy to trigger
2 - AA battery
1 - AA battery holder
1 - plastic or wooden pearl
1 - heat shrink that will fit over the motor shaft

This might cost you less then 10$ cdn.
1,98$ for both motors
1$ for the battery holder
1,98$ for both SPDT switchs
ok ok maybe 10$ is a lot!

I like to buy my stuff here

If you recycle it might be all FREE! Try searching old VCR, PS2, old toys, printer, etc
Back then, I use to recycle EVERYTHING, I got everything FREE, old VCR are very good for gears and something SPDT switchs!!! Playstation have great super good motors, the one that makes the laser move.

the tool to complet the robot
1 - safety glasses
1 - soldering iron
1 - glue gun
1 - wire strippers
1 - side cutter
1 - scissors, knife, x-acto, etc

You need some 1,5Volts motor, not 3V or no event 12V!!
Each motors are powered by a SINGLE AA battery! You will draining your battery if you use bigger motor. You can find them in toys or even at your local dollarrama, in little car, fans, etc! ( beware, they might really suck you battery down )

the SPDT swiths need to be really sensitive! I have order some the order day that where to hard to activated, that might cause some problems and the robot might not even avoid obstacles but rather hug them until death. These swiths are the most expensive part of the robot... around 1$ to 4$ each. The one I use are from Cherry.

You should check http://www.solarbotics.com for some great motors. They even have a SPDT switch in store! I have never tried them but Grant did.

Here is a picture of the Solarbotics switchs in use. The beetlerobot was build by Grant McKee, the engineer for Solarbotics but currently works for WOWWEE in Hongkong ( poor Grant! :P)



Step 2: Preparing the parts

Picture of Preparing the parts
Cut 13 pieces of 2,5inch long electric wire.

ps- cut 14 if you are supertisious.

Step 3: Preparing the parts

Picture of Preparing the parts
Now just remove around 1cm to each extremity of the wire.

In other word, strip the wire at both end.

That is 0.3935 inch to be precise.

After that you need to thin the end of each wire with your soldering iron.
Oups, I forgot to tell you to plug your soldering iron, HAHA you need to wait now!


Step 4: Group picture

Picture of Group picture
Here is everything you need to start building

ok ok I forgot the paperclips and ... what else?


Step 5: Start soldering

Picture of start soldering
solder each wire to your parts.

Step 6: The famous third connection

Here is the principal and most important thing about the beetlerobot.

It is call the "third connection"

In you AA battery you have 2 wires that provide 3Volts.

In reality, we only use 1,5Volts for both motors.

How can we get half the voltage? simple, you solder a wire like the picture below.
I solder a 2 inch long blue wire.

simple hey!

don't forget to browse the other pictures to see.

Step 8: Glueing the motors

Glue both motors on the battery holder

Make sure they spin forward...

I have just realise that this does not make any sense at all! :P

Look at the third picture how you can angle out the motors for speed.

Step 9: The back caster

Here you are going to make the third wheel, the back caster using a plastic or wooden pearl.

You can make something fancy or very simple. I took the BIG paperclip.

If you can not find a wooden pearl, you can use the paperclip directly on the floor. It will work but might catch on stuff while rolling around.

Step 11: The antenna!

You are going to give your little robot some way to feel the world.

Take the small paperclip and bend them to form some antenna.

Glue them on the metal plate pf the SPDT switchs.

I don't recommend soldering them because you need some aggressive acid-based flux or silver solder. If you don't have any experience in soldering, you will melt them.

I have already solder some using silver solder.

Step 12: Melting some shoes...

Take the heatshrink and shrink them on the shaft of your motors. Use a lighter to attach them.
Yo can put more layer if you want to, different colours.

I even saw some people use hot glue stick on the end of the shaft. They took 1cm of the glue stick and attach it directly to the shaft. BEWARE, you robot wil be VERY speedy and it might destroy itself on the first obstacle it will hit.

Step 13: FINISH!


You made you first Beetlerobot!

Cross your finger, put the AA into the battery holder and but the robot on the floor...

Does it work?

to stop it, you can step on it or simply remove the battery.

You can add some decoration to the robot. I took some big plastic shell find in the 2$ vending machine. I took one half and added sticker!

to debug the robot go to my website
It is in French and you will understand. You made a robot, you can read French now! :P

Oui = yes
Non = no
Est ce que les moteurs tourne? = does the motors turn?
Est ce que votre robot avance tout droit? = does it go in a straight line?

ok ok
I have added other steps to explain more about the robot and a also added a debugging section.

Jerome Demers
You can ask questions in French if you want too.

Step 14: How does it work?


ps- This robot does not stop the opposite motor when it touch a wall, it REVERSE the opposite motor so the robot will pivote and avoid obstacle the GOOD WAY!

BEAM powered robot will short circuit the opposite motor so the robot will need to push it's way out .

All the drawing where made with PAINT!

Step 15: How does it work? - the motor

ok this is simple

The electric motor spin when you apply electricity to it. It will spin clockwise and anti-clockwise when you swap the polarity.

If the robot spin in circle after installing the battery, swap the connection of the reversing motor.


Step 17: How does it work? - the motor and the switch part 2

Here you can see what happen when electricity flow through the circuit. Check the second picture.

So you can see that one battery will power BOTH motor when the robot run around your house.

The second battery is only to reverse the beetlerobot when it get stuck. SO this battery will last longer!!

Swap the battery to prolong your battery life and also the robot life.

If the opposite motor does not spin, this mean that you might have a weak battery or simply that the third connection is not working right.

Step 18: Debugging

I hope your cat is going crazy with the robot... maybe your dog?

Does your robot go in a straight line?
Here is a quick fix.

If the robot start rolling in circle you can add a "blob" of glue to the weak motor.

To know the weak motor, simply put the robot on the floor... if it goes to the left add some glue on the left motor. This will make a bigger shaft and makes the left side travel a longer distance and correct the path of the robot.

It does not mean that you motor is weak, it could just be the angle of your motor.

Step 19: Any questions?

Picture of any questions?
I hope everythings work's perfectly for you, if no, ask your questions here!

I took a picture of a special page from the wonderful book Junkbots, Bugbots, and Bots on Wheels by Dave Hrynkiw and Mark Tilden!

Mike Trzecieski wrote that back in 2001 at the Eastern Canadian Robot Games! I got my entire book signed by great roboticist! :D

I got Dave Hrynkiw, Grant McKee, Dave Simmons and his son Kyle Simmons, Scotty Dogma, Ori Barbut, Mike Trzecieski and Richard Weait the creator of the miniball... humm.. do you wonder what is a miniball? Do you want a instructable? :D LOLL

I am missing Mark Tilden signature!!!

Have a great day!

Jerome Demers
Quebec, Canada
Aditya M25 days ago

I also made it but it was little different.........

but the concept pretty matches with this......

I Don't have any picture of that!!!

Tbus1 month ago

This is a great lab experiment. I'm taking a Robotics Fundamentals home study course (http://www.ciebookstore.com/robotics-fundamentals-...) and this instructable covered a lot of what I learned in my class. Thank you!

mfernando33 months ago
AWESOME STUFF man. Just wanted to give you a quick praise. Thanks!
mkovtchega6 months ago
Hi Jerome, Pensez-vous que je peux trouver un SPDT switch dans un "Printer"-comme en anglais?.
hussein12 years ago
hey man can i use an mouse spdt switch?? please reply on this site please.
1 year old reply -.-'
The mouse SPDT would be hard to use, you have to de-solder, and the switch doesn't have an actuator lever (The metal thingy). But it could work! You could hot glue the paper clip on, that's what i tried to do, It fell off after the bot hit a wall 3x
CarlyAnne71 year ago
Can I Just Buy One From You ?
You can buy one from Solarbotics now!
Solarbotics Beetle Bot
meghams1 year ago
hey very nice bot ..!!wanna try right away ...but one thing which is boggling my mind is how you have fixed those motors in such a inclined angle..??
raghav571 year ago
i am raghav. i am 12 years old. i got all parts and i made some but how to stick SPDT switches and motors to battery holder.and where can i get heat shrink.the only part i didn't get.where can i get please say
rashtekar1 year ago
my bot is not going front when i coneect battries to the motors directly they work properly...but when i connect it to the switch and spdt switches it works slow and doesnt move forward...plz reply....i have to show it on monday..:-(
rashtekar1 year ago
my teacher is asking the uses of this beetle bot...what do i tell her????
TANMAYEE1 year ago
can u please help with the uses of this beetlebot?? do reply soon. Got an urgency. thank you. :)
Wisaam1 year ago
Can you please tell me the actual function of the SPDT switch and how does it work?...Please do reply..
hi it's cool idea...........!!!!
indradiana1 year ago
can i use two 3 volt motors by only using two 1.5 volt batteries?
does the beetle robot still work normally ?
niljo1 year ago
Hi!! i made the beetle robot, bt it wnt wrk if i let go of the switch.. i have to keep it presd..and the funny thng is tat wen i press the spdt swittch on right side, the left motor rotates and vice versa... cud u pls help me wit dis...
robomaniac (author)  niljo1 year ago

you are also there.

It is normal that when you press the right switch the left motor spin. That is compltely normal with the Beetle robot V1.

You told me that the robot does not move until you press the switch. This only mean that the third connection is not properly connected to the inside of the battery pack.

When you plug the battery both motors should spin forward. When you press the switch, the opposite motor should turn backward.

Make sure you have a good solder joint, a clean one with no flux or dirty thing on it.
hey thnks.. it really helped.. nw ts wrkng no prblm... thnks a lot jerome :)
niljo1 year ago
these are sm pics of the beetlebot i made.. i even made the third connection.. it wud very helpful fr me if u assissted me wit dis.. and my email id is niljos22@gmail.com
biocon771 year ago
can i use a Illuminated round rocker spdt switch?
robomaniac (author)  biocon771 year ago
well not really, only if you find an innovating way to trigger the swt with the antenna. then that will work. Rocket swt are stiff (hard to activate) so you need help with a lever system.
thanks also, can i use jumper wires
biocon771 year ago
do jumper wires work?
rimo1 year ago
it works ty sir
xXYEIROXx2 years ago
Hi there, i Did it! it works xDD ok to the grain, i wanna make one for one scientific faire in my high school but i wanna make it with an solar panel, so i dont see where i can put a thirth conection, if you know how plz make me know!
when my robot touches to a wall ,the switch will press till this process the robot is ok but after that the motor do not have that much force to push can you tell me what is problem...

reply at meetshadabmk@yahoo.com......pleaseeeeeeeeeeeeeeeeee
Yaryev2 years ago
Hello, my son really likes science projects, is in third grade. How or where do you recommend I can find information for my child to start learning about robotics? thanks
rnoorlind2 years ago
Thanks to this tutorial I got few burns :p from soldering iron and glue gun but I finished my robot. Although the wiring pic wasn't very helpful as with my robot I had one wire on every thinkable nob but the instructing pic had one wire about two wires. At that part things got messed up. So all was able to do was to sketch circuits until I understood it. But I thank you for making me think it through like that.
Thank you!
rajaavadi2 years ago
Where does that blue wire from motor go?
d'où vient le fil bleu aller?
aabuzaid2 years ago
hi how are you ,,, there are anyone can help me to built robot ,,,, i am studing mechatronics and there are project for robot course ,, my project is wowwee robotpet robot
kkeyan2 years ago
hey dude it is realllllly intrestinggggggggggggggg
rnoorlind2 years ago
At least the picture has metric system.
jsharma42 years ago
can i use spdt switch found in mouse fr d robot model?????????
plz reply fast..........i've 2 submmit my robo on 28 th
ashuki2 years ago
can you give me the schematic diagram ?

rkittukriti2 years ago
hey can i use it for my biology project!!??
rmkn212 years ago
In legazpi city, spdt limit switch is called micro switch
gpunia2 years ago
can you help me make a SPDT switch from house things pleaseeeeeeeeeeeee
and if you know please send me at punia.gaurav5@gmail.com
sanjo shaju3 years ago
can u help me to make a SPDT switch by using home thing!!!!!!!!!!

i will be very glad if you help me pleeeeeeeeeeeeeeeeeeese..........

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Hai the above one is me

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