Introduction: 4 Axis Robot Arm DIY

I made this project mainly to learn using servos with arduino. Of course I could buy robot arm kit like MeArm and start programming, but making it from scratch teach you more. I wanted design the arm simple as possible and that's why I chose 4 axis build. Idea for pinch mechanism came from small tweezers. Arm accuracy is not best possible but good enough for practice purposes. Using better quality servos, advanced programming and more sturdier building components, accuracy can be improved significantly.

Step 1: Demonstration Video

Step 2: Materials and Cutting Parts.

Main material is 3mm plastic sheet. I also used some thicker plastic for base and some MDF. But you can use what ever material you feel comfortable. Some brass spacers/stand off is used for attaching components together.Bunch of M3 bolts and nuts, small screws and 4 servos. Brass rod and sheet for pinch mechanism. For finished look I personally like to paint all my projects mainly with acrylics. Let's get started.

First print out blueprints. Then clue them directly to plastic sheet. Cut along with the outlines and drill holes. I used small bandsaw and handheld saw (last picture). For the base I don't have blueprints but I think you can improvise.

Step 3: Assembling the Frame

Assembly was quite easy task. Everything was planned ahead so I simply just screwed all parts together. Of course there was some minor tweaks to be done. I attached servo horns with screws that was included in a servo package. For the lower part of the arm I separated two pieces with one 12mm and two 6mm brass spacers. For upper part I used just one 12mm spacer. Servos are standard hobby servos. 3 Tower pro 9g micro and 1 tower pro 996.

Step 4: Making Base

Base is made from 10mm thick random plastic. First I cut square approx 100x100mm. With table saw I made those two grooves where I attached base of that arm. With 30mm forstner bit I made that embed area for servo horn. To minimize friction between base and MDF I sanded both surfaces with fine sandpapers. Then I painted them and added couple layers of silicone spray. To get best result I recommend using some kind ball bearing system here. But for practice purpose this is fine.

Step 5: Pinch Mechanism

Entire system is made from 0.8mm thick brass sheet and 2mm brass rod. Its very simple design compared to many other out there. I bend brass rod with nose pliers. Solder is same stuff that we use with electronics. I also added small foam pieces at the end of a "pinch". Foam adds more friction so you can grab round objects. Brass is very sturdy and easy to manipulate so its ideal building material for prototypes.

Step 6: Painting and Decals

Remove all dirt and grease with mineral spirit or similar product. Add primer. Small project like this I usually paint with airbrush. After painting I added some left over decals to make it look more interesting. Before final assembly I added clear coat of lacquer.

Step 7: Electronics

When using servos with arduino you need an external power source for them. Well you may power one micro servo direct from arduino but not multiple ones. You can connect all positive/negative leads together and signal wires should kept separated. Total of 6 cables are needed to control 4 servos. If you have two different power sources like me (USB for arduino and variable PSU for servos), you must connect all negative leads together.

To control arm you only need some buttons and a POT. First I made breadboard test setup and after that I made very simple expansion dock for arduino nano. Couple pulldown resistors for buttons and current limiting for leds. Leds indicates when you have saved pick and deposit places manually. This arm is not using any eeprom stuff so you need to write coordinates directly to arduino for permanent use.

Step 8: Files

Software used : Google sketchup, Eagle cad and arduino editor.

Any comments are welcome. Thank you.

Comments

author
Rangav (author)2017-06-08

Hello Sir,

Very nice project, can i get the measurements in pdf plz

author
JesusP91 (author)Rangav2017-07-08

Comrade you managed to send the pdf with the measures?

author
Rangav (author)JesusP912017-07-10

Hello Sir, i need the measurements in format of pdf file, the length, whole size, cutting size etc... please can send that sir.

author
arun97raja (author)2017-04-01

could u please give more info about ur base and servo attachments

author
Robot55 (author)2016-10-16

Great project you made here. Have you got the schematics of this project? Could you send it please? By fritzing or another program like that.

Thank you.

author
MartinO69 (author)Robot552016-12-26

I did this on circuits.io

https://circuits.io/circuits/3588726-4-axis-robot-arm-diy

author
fortzero (author)MartinO692017-01-03

Good job Martin ! It's nice to see that people are making improvements to this guide and helping others. Open source FTW :)

author
fortzero (author)Robot552016-10-25

I only have eagle schematics available. File name "control.sch"

author
bayteksan (author)2016-12-14
Have a nice day. Error loading code. I'm waiting for your help. Thank you.

Cords:16: error: 'Pick' was not declared in this scope

Cords:17: error: 'Home' was not declared in this scope

exit status 1

'recording' was not declared in this scope

author
MartinO69 (author)bayteksan2016-12-26

I guess you are uploading only one file to your board, Functions Home and Pick are declared on the F8ULMPIN2393LG file. I had these error messages while I was trying to build it on circuits.io... I just merged the files into one and that did the job.

I'll be trying this soon at home with the real board and see if it works (I've only been playing with Arduino for a few days)

You can check this for the code too. https://circuits.io/circuits/3588726-4-axis-robot-arm-diy

author
Mohamed traore (author)2016-12-03

It is a good projet please shall you give mee the pdf and electronic design

author
iozsi1990 (author)2016-11-20

Hello! How can I decrease the movement speed of the servo?

author
islame16 (author)2016-10-23

great effort made by you

I need your arduino code please

author
fortzero (author)islame162016-10-25

Just download all *.ino files under step 8.

author
mjr567 (author)2016-10-05

Hey, lovely project you did and am looking to do it during my holiday.

Do you have the full the drawing with full demensions? If yes, may you please send them to me at molebogengjr@hotmail.com.

author
BharanidharanK (author)2016-10-03

Fanstastic. Can you share the drawing original files to technocrat.bharani@gmail.com

author
rohit kashyap (author)2016-09-11

Supp
Its an amazing arm
Was going through your code and found this in the setup: base.attach(6, 550, 2700);
what are the 550 and 2700 values for?

author
fortzero (author)rohit kashyap2016-09-15

Hi

Those numbers are pulse width in microseconds. Check link for more information.

https://www.arduino.cc/en/Reference/ServoAttach

author
ИгорьА1 (author)2016-06-29

Wow! Let's play tick-tack-toe!

author
iozsi (author)2016-05-21

Congratulations for your work ! What values have R1-6 , R7-8 and the potentiometers ? Do you have the project drawings in pdf format? Thanks!

author
fortzero (author)iozsi2016-05-22

Resistors for leds are 270 ohms and for buttons 10k pulldown resistors. I only have those drawings in original format.

author
iozsi (author)fortzero2016-05-22

And the potentiometer ?

author
fortzero (author)iozsi2016-05-22

aah, its 10k, but anything in k ohm range is fine.

author
iozsi (author)fortzero2016-06-08

Hello.I made the robotic arm but i can't make him to move correctly . Probably i wrong combined the parts of the code in to the final program . Can you send me the final program? The email buchman.stefan@yahoo.com . Thanks.

author
fortzero (author)iozsi2016-06-10

The code that I uploaded is final version. Check your connections and compare them to arduino and code.

author
Jonathanrjpereira (author)2016-06-07

One of my favourite Robot arm Instructables!!

author
mjrovai (author)2016-05-25

Congratulations for the amazing project and to be the great winner on Robotics Contest 2016! Great work! Greattings from the south of the world!

author
fortzero (author)mjrovai2016-05-25

Thank you.

author
PaulSS (author)2016-05-24

This same design has existed for a long time hasn't it? I'm pretty sure you can download the plans for it.

author
Matheus Mota (author)2016-05-12

Really cool
I`m having troubles printing the model, do you have to any tip to print it in the right size in sketchup?

author
fortzero (author)Matheus Mota2016-05-14

I think this link will help u out.

http://tinyurl.com/3987ylz

author
Matheus Mota (author)fortzero2016-05-17

Thanks man!

author
phenoptix (author)2016-05-05

Superb job! I, of course, would still recommend MeArm. But then again it does pay my mortgage so I'm biased. Great job, really love it.

author
fortzero (author)phenoptix2016-05-08

MeArm has inspired me a lot during this project. So thanks for sharing your ideas and inspiration.

author
mocivnik (author)2016-05-04

Don't want to ruin anything, but..this is a 3-axis robot, not 4. The gripper doesn't count as an axis.

author
fortzero (author)mocivnik2016-05-08

Thanks for pointing out. I really thought this is 4 axis :).

author
Raphango (author)2016-04-20

Awesome project!! Congratulations!!!

author
JoeyyBoyy (author)2016-04-19

Very cool! I'd to build this project to play a game chess. Could the design be easliy modified to suport a longer reach, across a standard chess board?

author
fortzero (author)JoeyyBoyy2016-04-19

This arm has reach about 22cm. So if you need more reach for your arm then I highly recommend making a new design. "Pinch" mechanism might have enough power to pick up chess pieces but pivot points needs more power/bigger servos.

author
maxxe (author)2016-04-19

great project!

author
wirecut (author)maxxe2016-04-19

Good job. Very very fast, more faster that the Theremino ARM, a similar project here:

http://www.theremino.com/downloads/automation#arm

and the video are here to evaluate the speed:

and here:

author
Dzefri (author)2016-04-17

Great project! Check mine robot arm if you have time. :-D

author
fortzero (author)Dzefri2016-04-18

Nice MeArm project. It's nice to see that you don't need any special tools to make small scale robot arms.

author
Biodynamic (author)2016-04-17

Very cool! The arm moved way faster than I expected. I just saw a video of an similar arm making fast food burgers. A few upgrades and you could be getting offers from some pretty big businesses. https://www.youtube.com/watch?v=iQ_fSP3LGw8

author
fortzero (author)Biodynamic2016-04-18

Actually I was thinking same idea. Not burgers though but a pizza making bot :) Eventually robots will take out all repetitive and linear work from us.

author
ThomasK19 (author)Biodynamic2016-04-17

I'd rather wait for the Sub-Etha Sens-O-Matic xD

author
JoseA124 (author)2016-04-17

great job, thanks for sharing.

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