Picture of Pocket Sized Robot Arm #meArm V0.4

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.

We sell a kit here but all of the files are freely available so you can build your own! We're based in the UK but if you're in the USA check out the Hackaday store here and for global distributors see here.

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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Jazzmyn made it!9 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.



Very nice! You should call it the platypus and keep the iconic shape of the gripper :D

phenoptix (author)  Jazzmyn9 months ago

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

Jazzmyn phenoptix9 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.
onehourcleaner made it!3 months ago

Great instructions and very cool kit. Waiting on Adafruit shield to run all four servos with plans to use PSX library/controller to keep on my desk for any afternoon office doldrums. Thanks!!

morgan.fabian made it!10 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.fabian9 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: http://www.thingiverse.com/thing:616239/#instructions

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

patricksan11 days ago
Great project!
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PumaBare made it!14 days ago

Thank you ever so much for this instructable, I completed the build about an hour ago thanks to your help, appreciated.

SteveL81 month ago

Thanks for posting this project, but I facing the problem when i connect all 4 units servo to arduino uno, i can't use it together at the same time, how to get the powerful power source for the 4 units servo?

borodatch1 year ago

Awesome project! Thanks.

Please, tell me a thickness of material.

phenoptix (author)  borodatch1 year ago

It's 3mm acrylic, 1.4" is about right I think (excuse me if that's wrong I used my mental google and it's not as good as the real thing...)

HaA2 phenoptix1 month ago

can i use 2mm?

3mm =~ 0.118". 1/8" = 0.125".

Archimmersive2 months ago

Hello, I'm a bit stuck in my project because I can't seem to find a way of screwing the large servo screw between the lever and the servo horn. The screw just doesn't seem to fit in those tiny holes, and in the tutorial it shows the screw going until the other side. Am I supposed to force it until it opens a bigger hole in the plastic? Also, the screw doesn't seem to go through the lever (Central lever RHS). Am I doing something wrong? Thank you

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I'm having the exact same problem trying to fit the long screw into the tiny holes. Have you found a solution?

I had the same problem. I guess it was the screw that comes with the SG90. The ones from the kit are smaller. I just cut the screw and then forced it trough the hole of the lever. It worked fine and It's fixed strong.

alexfermon made it!1 month ago

Just finished mine! Let's see what i can do with Arduino + bluetooth + android!


I cant find acrylic with 3 mm thickness but i found many with 2 mm thickness. Would that work?

DejayRezme2 months ago

This is a really cool kit! I couldn't resist and ordered one right away :D

One thing that MIGHT be interesting is a new type of gripper which one maybe could 3D print: https://youtu.be/Q1MBIaNuLa8?t=5m13s

cristian.santafe.75 made it!2 months ago

Very Nice, thanks for the wonderfull project. We made it in colombia.!

flegarrec2 months ago

Hello, i am using MeArm v0.4.1 from the phenoptix website to play with my children, but 2 months after i still cannot :(. Too bad, because i always dreamed about having such an arm to play with.

I get a lot of shaking on 3 of the 4 servos, thus i cannot use it. The only one ok is the one controlling the claw. I use a separate power (from a Samsung GS5 phone USB adapter 5V-2A) for the servos, while the arduino nano is using another one.

- I tried to put a capacitor accord the servos power line to calm current peaks. But it does not work.

- I also changed the Arduino library for another one that allows controlling the speed of moves to slow them down. It is now much less brutal when moving, but still shaking like mad cow.

- I tried linking the servos ground with the arduino ground. Does not change anything.
- I tried connecting the shaking servos on the arduino pin of non-shaking one. Does not work. Still shaking

- I will soon have to try removing the servos to test them without the arm weight. I saw in another forum that the weight of the arm may prevent them from reaching their targeted position.

Anyone having an idea to help me?

phenoptix (author)  flegarrec2 months ago
Which servos were you supplied with your kit? Email me at ben at mearm dot io and I'll get you sorted!
RickyS42 months ago
Hi! I just got this today and put it all together. Everything looks like it's in the right place, but I think something might be wrong with the servos. They sound like they're constantly running. Also my robot arm sort of twitches every couple of seconds. Any help would be great!
HobbesC3 months ago

What is the dimension for the acrylic sheet if I have it laser cut ?

phenoptix (author)  HobbesC3 months ago
300 x 200 x 3mm
waynevanwijk3 months ago

Looks great - I have servos on order and can't wait to get started on the build. A few questions in the meantime...

Looking at the file I am assuming that the material thickness is 3mm - I didn't see it specified in the instructable (although I did skim read it).

In the file you have some lines black and other lines red. As far as I can tell all of these are cut lines. Is this a correct assumption or am I missing something?

phenoptix (author)  waynevanwijk3 months ago
Hi there, yes 3mm material and all the lines are cuts! Look forward to seeing your MeArm!
jkatila4 months ago

Thanks for shering. Great project. Have to do couple for students. Will be used with picaxe. Now testing with Uarm shield and mousecontrol software.

SoundGuy77 made it!4 months 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!

RalphCrutzen4 months ago


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)  RalphCrutzen4 months 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:


CCCSuffolk4 months ago
gökhany5 months ago

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

I did that! very nice!!

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