Picture of Pocket Sized Robot Arm #meArm V0.4

*** We're now running a Kickstarter for an Open Source Controller for the MeArm ***
*** Please check it out here. Thanks for all your support with the MeArm Project! ***

The #meArm is a Pocket Sized Robot Arm. It's a project started in February 2014, which has had a fantastically fast journey to its present state thanks to it Open Development as an Open Hardware project. Version 0.3 was featured on Instructables back in April 2014 and we've seen it built all over the world, from its home in the UK to the USA, Mexico, Switzerland and Japan to name but a few.

All of the previous builds have helped us iterate a thousand tiny improvements to the current version the v0.4 which is most likely going to be our v1.0.

All of the previous versions and this can be found on thingiverse.

This guide covers how to build the v0.4. Currently there is code available for the Arduino, Raspberry Pi, Beaglebone Black and Espruino.

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Step 1: Gather your parts!

Picture of Gather your parts!
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The #meArm was designed with economy in mind. It is understood that laser cutters aren't the most common tools but there are more of them out there now than ever! First you'll need a set of parts. Grab the dxf and use a cnc mill or laser cutter. For the v0.3 we also had people 3D print the parts. If you get a kit from us or order the parts in acrylic you'll have to remove all of the protective covering. It's not the most fun job but the end result is better!

Next you'll need all of the screws and nuts. We use M3 (metric 3mm) standard parts. The number of these to build the latest version is:

Nut x 10
6mm x 9
8mm x 12
10mm x 3
12mm x 7
20mm x 4
Washers x 0 (we removed these as nobody ever used them!!)

You could no doubt find imperial sized counterparts, as a nation you managed to get a man to the moon with foot pounds per square inch so I'll leave the conversions in your capable hands (in case of residents of Liberia or Myamar ignore the bit about the moon).

You'll also need 4 hobby servos. We tend to use the 9g resin gear ones. The metal gear ones with the same footprint are better but they're more expensive.

Phenoptix is a commercial operation (when I remember) and we do have complete kits available as well as the component parts.

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morgan.fabian made it!6 months ago

thanks for the fun project! i finished a 3d printed version today. excited to start programming it, just waiting for my arduino to arrive.

phenoptix (author)  morgan.fabian5 months ago

Very cool and very slick!

I want to know how programming the mearm V0.4 with potenciometers y with arduino, also if you can help me for programming the procces automatic of the Mearm V0.4 with arduino. Where can meet the information.

Waitting soon answer,


Great to see it can be printed! Did you find the files somewhere, or did you make them yourself?

Nevermind, I found this:

Yes thats where i got them as well. Glad you found them!

Jazzmyn made it!5 months ago

Thanks so much for posting this project. I loved building and reverse engineering this project. I had some troubles designing my own but that is where the best learning comes from. I am very happy with the final result. Take a look if you have time.

phenoptix (author)  Jazzmyn5 months ago

That is incredible! Have recently gained access to a Replicator 2 so might just have to build one!

Jazzmyn phenoptix5 months ago
The gripper head still needs work. My mounting holes are a little off and the head sits at a slight angle. The main beam could use some weight reduction as well. As with any project it is a work in progress.
SoundGuy77 made it!7 days ago

Made v0.4 from wood! i made a mistake or two along the way (put some parts the wrong way in) but found them out and now it's complete!



I use an Arduino Uno with the meArm. When I connect more than 2 servos, they move in a stuttering, shocking way. Like there is not enough current to drive them.

In the picture, you can see how I connect the ground and 5V to the Arduino. (I left out the other wires and the servos for simplicity).

What am I doing wrong? Or did I buy the wrong servos?

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phenoptix (author)  RalphCrutzen12 days ago
Hi Ralph, have been watching your progress on twitter! Apologies for the lack of much needed set up guide for Arduino. Running the servos directly from the Arduino can cause power issues. Ideally run a 5V or 6V supply rated at around 4A to power the servos. Tie in the ground from the arduino with the power supply so they have the same reference and use the PWM as you would normally from the Arduino.
Running from the USB will only allow you 1A total power before the poly fuse will trip!

It worked! Thank you very much!

At first, I forgot to connect the ground from the Arduino to the power supply. This was the result:

CCCSuffolk11 days ago
gökhany1 month ago

Hi Ben. What are the characteristics of this servo engine?

I did that! very nice!!

renatico472 months ago

I want to know how programming the mearm V0.4 with potenciometer y with arduino, also if you can help me for programming the procces automatic of the Mearm V0.4 with arduino. Where can meet the information.

Waitting soon answer,


phenoptix (author)  renatico472 months ago
Potentiometer code and auto stuff is all available on github!
marcelocamposs made it!2 months ago

Genial project !


This is a great project; my friend and I are interested in robotics and are using this to become familiar with the workings of arduino. We've built the arm, but I'm having some trouble finding the schematics for wiring the arduino. I don't have a shield right now, but I've seen several pictures of breadboards being used. Is there someplace that has instructions for how to wire the arm?

phenoptix (author)  joshua.santarelli.92 months ago
Sorry for the delayed reply Joshua! There is a wiring diagram in the comments here somewhere, essentially all you need is 4 PWM pins from the Arduino and separate power supply for the servos (ideally).

No problem! I can't seem to find the comment you are referring to, unfortunately. I found one about using a breadboard as an Arduino, but I'd like to do something like you have here: Thanks for your help.

BobH54 months ago

Is it possible to control this without a micro-processor by using RC transmitter/receivers?


DougJS made it!2 months ago

What a great Christmas present. Constructed it in about 2hrs without any real hitch - there was one piece missing for whatever reason, anyway not a major problem as I'd downloaded the PDF template so made a replacement out of single sided PCB in less than 10mins. It took longer to make up a noddy chassis with 4 pots and 5 centre off two way toggle switches plus Arduino and Adafruit 16 channel I2C servo driver, oh and order/buy said bits. After some experimentation I decided the base servo needed beefing up so I replaced it with a Hitech 300-BB (really old but I've got a few brand new ones) - somewhat dim photos attached. Now to improve the software and get it doing something autonomously.

I have fitted the new servo without compromising the ability to put the Mearm back to original design standard.

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txoof3 months ago

What are the size of these servos? Can you offer some dimensions?

peter5074 months ago

in this part (in picture 1) has a small diameter hole and a screw M3 hard to enter. Is it necessary to enlarge the hole to bolt passed easily and clamped to this part (2 in picture)? If it does not widen the shoulder will be very hard to move

phenoptix (author)  peter5074 months ago
The hole on that part is a larger hole and the screw should pass through. I understand that you got the parts cut yourself so their tolerances will likely be different to ours. You should be able to widen it slightly with a screwdriver or drill bit.
How thick is the acrylic used in the project?

3mm acrylic

gunnlaugursig4 months ago
I realy, realy, like this project! I'm planing to have acrylic cut for me, but I can't find it, or maybe I missed it, while reading through the instructable - how thick is the acrylic you use for the project?
judas794 months ago

I tried getting the meArm to work with a Wii controler with a wii breakout. Just a lot of shaking going on. Any guides on using the Wiii with the meArm and arduino mini pro? I also had trouble getting the meArm Wii code to compile...had to add the line "#include <i2cmaster.h>" to get it to compile. Other than that it looks fantastic.

peter5074 months ago

Hi !

I've send .pdf file to company which is cutting in acrylic. From pdf they will cut it correctly ?

phenoptix (author)  peter5074 months ago
Hi Peter,
That's a little of a tough one for me to answer! Lots that can be done wrong in laser cutting. Pdf should be the right size though.
mimax4 months ago

I am a beginner, according to your guidance on their own, but I don't know the specific how Mearm to connected Arduino?Thinks

judas794 months ago

I finally got mine built! Thanks for the metal gear servo, I'm going to replace the stock base servo with it, after I play with the arm for a while. The only part of the instructions I had slight trouble with was the right/left forearm section. It took me a while to notice that one side of the forearm was attached to the inside and the other to the outside of the supports....just figured I would mention it in case somebody else runs into the same build delimma.

niccokunzmann4 months ago

meArm V0.41 was a basis to create my alpha version arm. It uses 4 M screws and the Modelcraft RS-2 Servo. It was nice to understand how it works. We want to use meArm at a Coder Dojo.

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JesseW24 months ago

Great project! I built V0.3 and I'm trying to figure out what the differences are between V0.3 and V0.4. I see there is calibration guidance now and even if that is the only change, it's certainly worth it!

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