MeArm Comparison

We needed to have a project for the Young Roboteers to play with that would give them the sense of being the brains behind the machine, and help them to understand that without input and instruction some machines won’t do anything. We also wanted to be able to perform a simple task, moving cotton reels from one side of a line to another, we decided that the MeArm kit would be a perfect project so we explored two different options for building a MeArm kit.

Before I go further, let’s start by explaining what the MeArm is, it’s basically a robotic arm that comes as a flat pack kit, in order to put it together you need very little more than a screwdriver, an allen key and an enormous amount of patience. When you’ve finished constructing, you wind up with a robotic arm that can be coded to perform tasks.

The official MeArm website says “It is a great kit to get you started in the world of programming, electronics, robotics and engineering! It has been described as the "Perfect Arduino Project for Beginners" by the website Lifehacker.” It’s also possible to use a Raspberry Pi, Beaglebone Black, Sparkcore and Espriuno to code the MeArm. The MeArm hardware and its instruction code are both Open-Source, which means that the creator of the project has made it freely available to anyone and that the information may be redistributed and modified, so basically anyone can play with the code and design.

Building Your Own - Thanks to the Instructables website you can build your own MeArm from scratch if you have access to a laser cutter or know someone who can accurately cut the parts from acrylic sheet or plywood; or you can 3D print one for yourself using the MeArm 0.4 Printable (.stl) files downloadable from Thingiverse. The Instructables files for the laser cutter come as a .dxf file so it should work on most laser cutters, the parts are cut from an A4 piece of 3mm acrylic. As well as the parts you’ll need a supply of M3 screws in assorted lengths, quantity and lengths are given with the latest build instructions. You’ll also need 4 servo motors and a means of controlling your MeArm, so some form of Arduino, a battery pack, joystick and software will also be required.

The Sintron MeArm Kit, comes from China and costs £26.95 - we got ours from Amazon – though you can find variations of this kit from lots of different places.

The Mime Industries MeArm Kit comes from a company based in the UK in Nottingham, Mime offer two variants, a basic kit that costs £32.99 for just the MeArm parts which comprises - a set of laser cut acrylic parts, all the screws and nuts you need, and four servo motors.

Or you can buy the Deluxe Kit for £76.99 that contains the basic kit plus a Brains Board - for programming, Joystick controller and battery pack (takes 4 x AA batteries not included!).

Sintron – All the acrylic parts, fixings, 4 x TowerPro SG90 9g Micro Servos, 1 x Sintron UNO R3 Board with a USB cable, 1 x 830 Point Solderless Breadboard, 1 x Battery Box, 2 x Single Unit Joystick Modules and a set of Dupont Cables.

Mime Industries – Again all the acrylic parts, servos and fixings you need to build the MeArm plus a ‘Brains Board’ which is Arduino compatible and has an LCD screen so you can see what you’re coding. The brains board also comes with a set of joysticks that help control your MeArm and are attached to a PCB which can then be screwed to an acrylic panel to make it look more like a controller.

Building the Kit – Both kits were fiddly to put together, it’s not something a small child could do on their own, they would need adult help and a lot of patience, getting some of the parts in to place can prove tricky but it can be done if you persevere. You need instructions, only one company of the two we tested supplies any!

Buying A Kit – If you don’t have access to laser cutters or 3D printers you can buy a kit that can be put together at home with simple tools. We looked at two different ‘Deluxe’ kits.

How Do They Compare?

It’s a real case of “you pay your money and you takes your chance”, whilst the Sintron kit is cheaper, in our opinion it most certainly isn’t the better choice kit on a number of levels.

In no particular order… The servos in the Sintron kit (clear acrylic model in photo above) have plastic gears which don’t take kindly to too much action, in fact one of our Sintron servos died within moments of powering the kit up! The Sintron servos are SG90’s with a torque of 4.8V and matching speed and have a bushing rotation which means they’re not as friction free as dual bearing gears.

The Mime servos on the other hand are much higher quality MG90’s and have a torque of between 4.8 volts (V) and 6.0V and a matching speed, the gears are metal and they have dual bearing rotation. They can achieve a greater torque at higher voltages with these servos and survived being hammered by 5 children for 45 minutes straight!

The construction of the Sintron kit is rather flimsy and not as strong as the Mime kit and on top of that the Sintron kit has absolutely NO INSTRUCTIONS to enable you to put it together! The Mime kit (blue acrylic model in the above photo) on the other hand has a Resources Page that includes a pdf building guide that you can print off. Plus the code that is on the Brains Board, cutting files for your making own MeArm should you want to just purchase the brains board and controller from them, instructions on how to hack the code of the Brains Board and running it using Scratch (Snap).

Connecting Once the Kit is Built.

The Sintron kit as mentioned above, comes with no code to run the MeArm straight from the box and finding it for the novice can be a total pain. We gave up looking eventually and put our own together, which we'll add to the resources section when we’ve tidied up the code as it did the job but wasn’t perfect. The cheaper kit is not something you could do with small children who just want to build and play!

There is also no brains board with the Sintron kit, instead you end up with a rats nest of wires (see photo above) connecting the single joy sticks to the breadboard and to the servos and UNO board, the joy sticks are loose and don’t look like a mini controller upon use. There are absolutely no wiring instructions at all. We were lucky that we had experience so knew what needed to be wired to what, for those that don’t know it would be a nightmare.

The Mime Kit on the other hand was a lot easier to sort out, the brains board and the controller plug in to each other and the code is already installed on the Brains Board so you can start to use the MeArm as soon as its finished being made.

Performance - The Sintron kit was very flimsy and also highly erratic in its movement, and within moments of powering up, the servo on the grabbing claw ceased to function, it started to get very warm after only a few movements of the claw and then just died.

The Mime kit was a lot sturdier and withstood being operated by a group of children that wanted to test the arm to its limits, the Mime kit survived! The Sintron kit was so poor that we decided to go ahead with the Mime kit.

Summing Up - In all honesty, I initially thought the Mime kit overpriced and still do a little, I wanted to be able to say that there was no difference between the two kits, so go for the cheaper option and save money. However in terms of quality and reliability the Mime Industries kit wins hands down to the cheaper Sintron kit. If you can code and understand the wiring etc. then you could save some money by buying the cheaper kit, but in terms of time, reliability and durability it’s better to buy the more expensive kit.

There are other options to explore in the form of 3D printing/laser cutting our own parts and sourcing our own components and writing our own code (that part done already), whether that is a cheaper option and just as reliable as the Mime kit is to be decided, and once we’ve tried we’ll share what we discover. In the meantime my advice is to go for a Mime Industries MeArm kit, your patience and your frustration meter will thank you for it!