Arduino multifunction shield robot arm

An Arduino Uno combined with a multi-function shield makes a great inexpensive starting point for projects. I had an extra Arduino-compatible laying around so picked up a multi-function shield with the idea to use it as a teaching tool. It has a 4-digit 7-segment display, a buzzer, three pushbuttons, a trimming pot, and a number of headers for attaching additional things like up to three servos. That provides lots of opportunities to dabble and learn how to control physical hardware with Arduino code.

Arduino Multifunction Shield

I originally had just a vague idea of how I would use the Arduino + multifunction shield for teaching purposes. But then I decided to combine it with a project I was contributing to on Hackaday.io. The project started out as something called Cardware (which has since evolved quite a bit). The concept is that there are lots of hobbyist robotics components available like servo motors, controllers, sensors, etc. But to put together a complete robot of any kind you have to either buy an expensive kit (which may not even be available depending on where you live, e.g. Amazon does not ship to Thailand) or have the tools and expertise to fabricate something like 3D printed or laser cut body components. The talented project owner of Cardware developed plans for folded card stock as the body components in which servos could be mounted and then the components assembled into a complete robot.

More details on the development of Cardware will be in another blog post. Now I will just jump to the finished result of combining Cardware with an Arduino Uno + multifunction shield.

I introduced this to the teacher who runs the coding club at my kid’s school. They are already using Code.org to teach primary school kids coding. The kids in the club make art and games using Blockly. Adding a real world physical component like this gets kids excited and is what makes robotics such a great way to inspire young learners. There are many kits available targeted at that space. But I like this approach because it is much more DIY. It is more challenging than snapping together pieces of a kit so more adult help is needed. The Arduino can be programmed using a Blockly-like tool within the Arduino IDE. So kids can actually program the robot arm to move the way they want it to.

B-7000 adhesive is the real deal

It’s probably old news to experienced makers and crafters, but I only recently discovered this adhesive called B-7000 that works well on a number of plastics. Several projects I built utilize plastic bottle caps to fashion wheels, often requiring gluing a couple of caps together. Those are typically made of LDPE or HDPE. Empty yogurt containers, made of polypropylene, were used in another project. I had poor results using the cements I had on hand (hot glue, cyanoacrylate, “all purpose” plastic cement). After a little research I learned of B-7000 and, happily, it is available on Aliexpress at attractive prices.

A few test pieces showed it forms a very strong bond on the two materials I previously had trouble with.

The test items were subjected to stress testing by a very strong six year old. Those two bottle caps are inseperable. The yogurt containers bonded pretty well but did come apart with only a moderate amount of force. Good enough for most projects but if a super strong bond on polypropylene is desired then a different adhesive is needed.

Of course, like so many items on Aliexpress that come from China, you get the silly English labelling.

“Surprise adhesive force” and “Stimulate the taste-free”, chuckle. But the adhesive works very well and at about US$1 for a 25ml tube it is a good deal.

In the US you can probably find it at a local craft store and there are many sellers of it on Amazon. Being in Thailand means there are few local sources for specialty craft materials such as this adhesive and Amazon does not ship here. But Aliexpress has nearly everything, and much better prices (that 25ml tube cost me US$1.00). You just need the patience to wait three weeks or so for it to arrive. There are plenty of sellers. Another option in Thailand is Lazada which delivers in under one week, but at several times the price.