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

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!2 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)  Jazzmyn2 months ago

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

Jazzmyn phenoptix2 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.
morgan.fabian made it!2 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.fabian2 months ago

Very cool and very slick!

peter50716 days 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)  peter50716 days 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

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?
judas7920 days 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.

peter50721 days ago

Hi !

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

phenoptix (author)  peter50721 days 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.
mimax21 days 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

judas7921 days 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.

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.

meArm Vn.01.jpg
BobH528 days ago

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

JesseW228 days 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!

phenoptix (author)  JesseW228 days ago
Thank you. It's the lever on the left hand side that's different in length and one spacer. There are a few more improvements to the pieces to cut down the number of ways you can build it incorrectly too!
Look forward to seeing a picture of your #MeArm!
kgroce11 month ago

This is a big hit in our local robotics group! :)

phenoptix (author)  kgroce129 days ago
That's great to hear! Do you have any pictures?! Would love to see the #MeArms of Nashville!
mhenriksen1 month ago

Just a hint: Acrylic is brittle and can start to crack over time. Acetal (Delrin) lasercuts nicely and is a lot stronger. Only available in white or black but white acetal can be dyed using Rit og Dylon textile dyes.

phenoptix (author)  mhenriksen1 month ago
Thanks for the tip! Will give it a try. We've not had any cracking as yet but will look out for the problem too!
richie011 month ago

sorry I'm new and not yet downloaded I can not spend the dxf to print or pdf are measures

omer.sobhi2 months ago

can you
suggest for me a cheap micro controller that can run this robot arm ?

phenoptix (author)  omer.sobhi2 months ago
A breadboard Arduino is a pretty cheap way to run it!

how can i program this robot arm with the board ? can u give me the code in c++
*sorry for my English*


minisumo_UK made it!2 months ago

Lovely design, I'd to remix the DXFs to remove the splines and get back to simple lines and arcs to allow our old Modella software to recognise the profiles.

Given the 2.6mm cutter there was a slight overlap on part that where aimed for laser cutting but not that you'd notice. The material in this case was a foam PVC board.

This has been great for exploring what we can do with this old machine, thank you!

futureshape12 months ago

Just made this - it was easier to build than I thought. But I have a couple of questions now that I've connected it up to to an Arduino (using the Adafruit PWM board and this code:

1) Is it normal that in some positions some of the servos make a bit of a buzzing noise?

2) I don't think the arm moves to its homing position correctly and also when I tell it to move just in one of the X/Y/Z axes it also seems to also move in other directions (e.g. doesn't follow a completely flat path when I tell it to go forward). Could this be that it needs some extra calibration? I see there's a way to set calibration parameters in the Arduino code, but I'm not 100% sure what they mean. Can anyone clarify?

phenoptix (author)  futureshape12 months ago

Sorry about the delayed reply. Think with Bob's code we need to make some of the settings a bit easier to access and also easier to calibrate. Will work on this! Please keep an eye on the github!

Thanks! I managed to calibrate it eventually, if anyone else needs to do this here's the process I followed, one servo at a time:

1) First of all, in the meArm constructor look at the angleMin/angleMax pairs for that servo. These are the minimum/maximum angles (in radians) that the servo should be set to in the physical space. E.g. the base servo goes from -pi/4 to +pi/4 (-45 to +45 degrees) - this is relative to it's centre location.

2) Get a bit of test code to drive the servo with a range of angles (in degrees from 0 to 180) until it reaches the 2 ends. When the servo reaches the min/max angles above in the physical space, make a note of the corresponding servo angle.

3) Use these angles (in degrees) in the sweepMin/sweepMax arguments when instantiating the meArm object.

ted99tw made it!3 months ago

Thanks and I made a Chinese one. Enjoy!

nawres1024 months ago

Video please!

phenoptix (author)  nawres1023 months ago

Just a few of them here. From my kitchen table to Taiwan, Japan, Mexico and the USA!

borodatch4 months ago

Awesome project! Thanks.

Please, tell me a thickness of material.

phenoptix (author)  borodatch4 months 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...)

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

jstaněk14 months ago


Really awesome project, I did something similar, but much bigger.

Anyway, how thick is your acrylic sheet?


phenoptix (author)  jstaněk14 months ago

That's a cool arm! This used 3mm Acrylic. What in the box?

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