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.

This tutorial is for the v0.4. We now have a v1.0 available on phenoptix.com

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.

Step 1: Gather your parts!

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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SilvinoPresa made it!22 days ago

Thanks for the project! Really nice building the robot!

patricksan1 month ago
Great project!
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PumaBare made it!1 month ago

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

alexfermon made it!3 months ago

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

Jazzmyn made it!10 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)  Jazzmyn10 months ago

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

Jazzmyn phenoptix10 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.
cristian.santafe.75 made it!3 months ago

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

onehourcleaner made it!4 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!!

SoundGuy77 made it!5 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!

marcelocamposs made it!7 months ago

Genial project !

morgan.fabian made it!11 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.fabian11 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!

DougJS made it!7 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.

IMG_3733 -1.jpgIMG_3734 -1.jpgIMG_3735 -1.jpg

Good night sir!
I bought a Mearm but do not have the source code to be used in the Arduino, someone help me? I am meeting the Arduino now ..

my email is jfrdepaula@gmail.com
Thank you

Very nice project! Congratulations!
I tried assembly using a 2 mm acrylic, but it did not work fine. Some pieces broked catastrophically, such as claw servo collar, and some broked as i tighted screws, such as claw servo actuator and rectangular base of claw.

I am affraid on using acrylic again, so i will try with 3 mm mdf. I will post here when i finish it.
phenoptix (author)  Denis Massucatto10 days ago

3mm Acrylic works well, as will the 3mm MDF. 2mm won't work as it was designed for 3mm.

fansblink12 days ago

Nice Project, Can I use 5mm thick arcylic? and if you can, if later there were not functioning normally? Please help...

phenoptix (author)  fansblink10 days ago
5mm won't work without a redesign I'm afraid.
nishabe made it!11 days ago

The kit came from hackaday was not up to the mark. It was missing few bolts and few other parts missed self threading which made the job difficult. There were differences between photos in this page and the components that came with the kit. Altogether the kit was a disappointment.

At last I ordered the kit from microbotlabs and it turned out to be great! Clearly marked components and instructions.


Oh,such robot arm is great.But I think that it is a little easy to damage the robot arm during the assembled process while the robot arm is made by the acrylic.If the robot arm can be made by other better material,the robot arm would better.

Acrylic is a brittle material. If you are searching a more stable robot arm you can come here to get a robot arm which made by aluminum metal 6061: http://www.instructables.com/id/Build-a-multi-con...

You really should take a look a this robto arm. I happened to see this arm few days before.

SteveL82 months 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 phenoptix2 months ago

can i use 2mm?

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

Archimmersive3 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?

alexfermon Swigly3 months ago

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.

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

DejayRezme3 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

flegarrec3 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)  flegarrec3 months ago
Which servos were you supplied with your kit? Email me at ben at mearm dot io and I'll get you sorted!
RickyS44 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!
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