Lego drawing machine

We’ve been working on an art collaboration, and have built a drawing machine based around a pantograph and a rotating turntable. It produces a Spirograph-style pattern, which can be tailored by changing the arm length, pivot point, rotor speeds and turntable speed. The build is a prototype, and can be replicated with power functions motors, rcx, Nxt kits, or even old school technics kits. A build video will follow, but check the time lapse for a quick overview.

We used the power functions speed controller remote so that we can control the rotor speeds and directions, as opposed to the digital remote which only allows full on/full off.    If you were to replicate this build using NXT, you would have to set the Servomotor speeds in software, and then execute the program.  You can see in the video above that Shorna changes the drawing pattern at 0.08 seconds in the video.

Slow motion combustion experiments.

Wanting to illustrate combustion for GCSE chemistry using a classic demo with a new twist, I did a Whoosh bottle experiment filmed at 240fps.  The standard experiment involves setting light to methanol, ethanol or propanol in a polycarbonate water cooler bottle, and the rapid exit/entrance of gases through the neck causes a whoosh.

Filming in slow motion allowed us to discuss in much greater detail what was going on during the reaction, and to work out that the actual reaction is far more complicated than a simple equation.

The experiment was beautiful, filmed on an iPhone 6, and then slowed down in-app using SlowPro.

As an extra experiment, I then tried methanol in a volumetric flask, behind a safety screen in an empty lab, just in case.

A talking point and a teaching point.

Challenges:

Getting the lighting and safety aspects correct! (This is against CLEAPPS advice – never do this in an occupied lab)

Next Steps:

Using a TriggerTrip to take a high-res photo during the combustion process.

Simultaneous combustion of methanol, ethanol and propanol to compare burn rates and completeness of combustion.

Doodlebots @ STEM club.

Inspired by an article at Makezine on scribblebots, we decided to roll our own using some bits at school.

This video shows the bots in action in slow motion, and clearly shows how the eccentric vibration motor allows the bot to move in a circle.   We just used rubber bungs stuck onto the motor to create the offset motor.  We experimented with a range of pens, pencils and markers.  Sharpie style markers worked well with the sugar paper, but if you are tiling smaller sheets of paper, make sure to tape on the underside and make the seams as flat as possible.  The activity was great fun, and produced some crazy generative art, which was my lab wallpaper for a couple of weeks.  Check out the videos: