This ia a 3DPrinted robotic arm.

The design intent was to make something "easy" to build and quite cheap

It uses MG90S small servos for driving the kinematics linkage and a Pololu mini maestro 12 to control the servos (but this is my choice any other methods are valid)

All the pieces are 3DPrinted in ABS but any other material like PLA can be used

3D models in stl format can be downloaded for free at Thingiverse : http://www.thingiverse.com/thing:1015238

video :

ramp loop test :

preliminary tests video :

Part list:

n° 20 3D printed parts

· n°1 EBA_01.00.001.STL

· n°1 EBA_01.00.002_vertical_drive_arm.STL

· n°3 EBA_01.00.003_link.STL

· n°1 EBA_01.00.004_forward_drive_arm.STL

· n°1 EBA_01.00.005_horizontal_arm.STL

· n°1 EBA_01.00.006_triangular_link.STL

· n°2 EBA_01.00.009_servo_plate.STL

· n°1 EBA_01.00.010_basement.STL

· n°1 EBA_01.00.011_round_plate.STL

· n°1 EBA_01.00.012_R01_claw_support.STL

· n°1 EBA_01.00.013_R01_right_finger.STL

· n°1 EBA_01.00.014_R01_left_finger.STL

· n°1 EBA_01.00.015_drive_gear.STL

· n°1 EBA_01.00.016_R01_driven_gear.STL

· n°1 EBA_01.00.017_R01_ramp.STL (optional)

· n°1 EBA_01.00.018_maestro_holder.STL (optional)

· n°1 EBA_01.00.019_ball.STL (optional)

n* 3 Tower Pro MG90S servos

n* 1 SG90 servo (gripper) + 1 optional for the loop ramp

n° 7 M4 self locking nuts

n° 15 M4 washers

n° 7 M3 nuts

n° 1 M3 x 30 screw

n° 2 M3 washers

n° 4 M3 x 12 hex screw

n° 2 M3 x 12 TCEI screw

n° 2 M3 x 20 TCEI screw

n° 5 M4 x 20 round hed hex recess screw

n° 1 brass pipe 4 x 3 x 22 + n°1 4 x 3 x 26


The Arm can be driven in several different ways : sketches, potentiometers, joystick, WII nunchuck …. after several trials I found very "easy" to use a controller from Pololu: Mini Maestro USB Servo Controller. You can attach up to 6 – 12 – 24 servos depend of the controller type. It is provided with a free configuration and control program for Windows and Linux that give you the power to drive the servo in manual moving slides; in the mean time you are able to set the values of speed and acceleration for any singular item. You can also build sequences of servo movements and run scripts stored in the internal script memory that can be automatically played back without any computer or external microcontroller connected.

here the link of the Pololu servo controller: https://www.pololu.com/product/1352

------- UPDATE ------

add an instructables to drive it with Arduino, bluetooth module and Android APP made wit MIT app inventor


Step 1:

Connect two link arms (003) to the Triangular link (006).

Keep the M4 round heads screws to the inner side like shown on image and selflocking nuts to the outer side.


I design all the holes of joints quite exact to allow to make them more precise using a drill bit

The nuts are to be tightened till the locking of the joint, then consequently you must loose them until you obtain a smooth movement with the lower clearance between components. This rule is valid and is to be applied also for the following joint that involve use of self locking nuts.

<p>Can you plzzzz place a schematic scheme how to connect the servo's to the board? i see the first picture is for the Pololu USB servo Mini Maestro but i can't see which servo goes to what connector and the cable from the gripper arm has to be made longer ? </p>
<p>please reply ....</p>
<p>Can i use sg90 servos instead of mg90s servos, because the diagram does not mention anything about sg90 servos, so will there be any problem if i use sg90 servos??</p><p>please reply</p><p>thank you:)</p>
you can use them. They are dimensionally the same. Take only in account that mg servos are a little bit stronger and much affordable
<p>Thank you so much .... i have one more query to add up to it.</p><p>can this gripper lift an object of a bigger diameter?....because it is shown in the video that it can only lift a small ball</p><p>in my project i need to lift an object say like a square or a ball of bigger diameter ... or a 500ml pet bottle</p><p>the reason am asking this is because the grippers' grabbing area is downsized by the gears and servos underneath them.</p>
Thanks! Seems to be OK, not tested yet.
<p>Great project ;) I only have one problem with grasper (catching), but I will resolve it with rubber fingers or different mechanism ;) Thank You for this project :D</p>
<p>I have made MK2 version ;)</p>
<p>Just an FYI: In gathering the parts for this build I struggled to find TCEI screws. To clarify, TCEI is an Italian acronym meaning socket head cap screw, as in allen wrench type stuff! Hope it helps.</p>
Awesome! Now it only needs purpose!
<p>Nice &quot;weekend&quot; project - took me a little bit longer during the holiday (to mutch christmas cookies to eat). </p><p>I modifed the sweep-example from the arduino library for the first run. Now I&acute;m thinking if I should print the ramp our build somthing else to have a nice little application.</p>
<p>Nice one =) Thanks a lot!. Now i gonna make mkII, i hope new servos will be much stronger =)</p>
<p>Amazing! I am very impressed!</p>
oh! okay, thanq.. n can you share the code u used for the arm from arduino ?<br>
<p>Nice and versatile. I run mine from Arduino with old ps2 Mouse. Also added LCD screen to see axis for coding the mouse. (optional)</p>
<p>how did u integrate the arm with ur PS2 mouse ? any extra modules needed for that ?</p>
<p>No extra modules. Just wired the PS2 plug into Arduino and used some code found online to read movements and wheel. I use the &quot;zoom&quot; wheel to clamp and unclamp. </p>
<p>https://www.facebook.com/piotr.herko.3 </p>
<p>how did u integrate the arm with ur PS2 mouse ? any extra modules needed for that ?</p>
<p>Does anyone know how to find waterproof servos for this?</p>
<p>Do we need the servo controller if we just want to control it manually?</p>
<p>you can control it with literally anything that outputs 4+ PWM channels</p>
<p>I made this and such fantastic details! Kudos to theGHIZmo.</p><p>Now I have couple of updates to share. For the step 8 gripper assembly, revise for SG90 since we would have used all the 3 servos MG90S.</p><p>For the brass pipe, look for #8128 RND Brass Tube, 3.97mm, <a href="http://www.ksmetals.com" rel="nofollow"> www.ksmetals.com</a></p><p>I bought one from my local Dale hardware.</p>
<p>printed and assembled but i used all my arduinoss on other projects haha</p>
<p>do you have the program to make the loop with the ramp?</p>
<p>Did you ever get this program? I am looking for it too.</p>
<p>nice video</p>
<p>hi! <br>i don't understand what is the task of this part:</p><p>n&deg; 1 brass pipe 4 x 3 x 22 + n&deg;1 4 x 3 x 26</p><p>Where i can find it?</p><p>Thank you :)</p>
<p>Can anyone share the Arduino UNO Code?</p>
<p>Hey could you use a Hextronik HXT900 instead? i have nearly no experience with servos?</p><p><br>http://www.ebay.com/itm/Hextronik-HXT900-9g-Servo-1-6kg-0-12sec-Micro-Servo-Pack-of-4-/291255244466?hash=item43d02a56b2:g:cO0AAOxyThVTZRs2</p>
<p>anyone have make code for this that will work with arduino ?</p>
<p>there are several way to make it works with. I made available this :</p><p>https://www.instructables.com/id/Android-APP-to-Control-a-3DPrinted-Robot/</p>
<p>Very cool project and well designed indeed! Can't wait to get mine assembled and working. Just one thing I would like to point out. You have to read the whole thing very carefully (of course) to notice that some of the parts needs to be printed more than once. That really annoyed me when I thought I had it all printed and ready.. Otherwise great instructable :)</p>
<p>thanks for the reporting the issue. </p><p>Hope to have fixed it (added a part list with quantities)</p>
<p>This was a great project and well designed. I still need to locate some lock nuts, but temporarily was able to just add 2 nuts where possible and tighten them against each other. Now to work on the arduino code! (I hooked it temporarily to a reciever and used my DX8 which worked well too. </p>
<p>Printing right now! Hope I can make it work! :D</p>
<p>surely you can !!, I also had the same doubt :-)</p>
<p>I'm having trouble finding the brass pipe. Do you know where I can find it online?<br>Do you think it would be ok to just put a M4 screw instead?</p>
<p>I got the model built. It goes together very well. I used the Maestro board. It does have some nice features. I have one problem. The rotation servo tends to oscillate or chatter. I can prevent this by putting a piece of sandpaper between the base and the rotation plate. That damps the oscillation. I need more drag on the servo so the mass of the arm doesn't cause the chatter. Any suggestions?</p>
<p>Problem solved. Junky servo!</p>
<p>I'm just printing parts now, and I've ordered servos - they will take a while from China. These parts are very cleverly designed. What CAD software did you use?</p>
<p>Looking forward to building this! Can you please recommend a battery to power the servos?</p>
<p>I used a power supply not batteries </p>
<p>Ciao in primis tanti auguri di buon Anno. Ti ho mandato un messaggio privato qui su instructable. Grazie</p>
<p>Wow. I don't think I can afford the parts for this right now, but it was a pleasure just to go over these instructions. The diagrams are very clear, and the finished arm looks really cool. Thanks for the inspiration!</p>
<p>Thanks for the appreciation.</p>
<p>We're trying to build one of these, and trying to source the hardware from McMaster-Carr. What is the difference between the Hex and TCEI screw? From the internet I have cleaned TCEI means recessed hex in Italian, but you already mention hex, so what type of screw are you meaning? Thanks!</p>
<p>sorry, I realize now that the part list in the first page have some inaccuracies (was an early release that I didn't have time to check) I'll fix asap.</p><p>You're right TCEI are recessed hex with cilindrical head</p><p>while for hex I mean hex head screw</p>

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