Pi Wars – sHazBot is born! – The Final Push

Team Cyberchondriac – Pi Wars 2015

Weapons, Sensors.. and a paint job.

So, skittles… How hard can… :/

I have been spending a lot of time with OpenSCAD lately – and the 3D printer at Cheltenham HackSpace. It is still pretty science fiction to me that I can design something in software and then actually turn that design into a real physical object.

The only limit therefore is your imagination. And when it comes to weaponising robots, I appear to have a fairly wild imagination!

Skittles Cannon


(ball pusher v1.0 – nope, that didn’t work (and more wheels))

The basic principle is a spring, loaded into a tube and a 3D printed ‘catch’ to hold it in place under load. It became rapidly apparent that the amount of force holding the spring back was going to take some shifting to actually release the thing. I tried several versions of a release mechanism using solenoids and nothing had the power to shift it. Back to the drawing board.

After much head scratching and (as previously mentioned) bashed fingers I finally came up with a design that actually gave me a reliable and controlled release of the mechanism.

You can see it in the picture below…


(who left that paint can there? 😉 )

Once the trigger was complete, I built another small relay board that was required to hook it up to the GPIO ports on the Pi. Thankfully – that bit was straightforward. Something worked – first time!

It then dawned on me that something else was definitely required – practice. Driving up to a ball and NOT touching it until you actually want to turned out to be slightly harder than I had first imagined. I also then decided to fine tweak the timing of the release mechanism to fit the layout of the areans. The bot will now prime the trigger, drive forward to pick up the ball, and then shoot. This seem to give the most reliable way of a straight shot. The skittles video shown further below however was probably my 20th attempt..

Glad Rags & Handbags.

Proximity, check. Skittles, check. Line follower, check. Three point turn, a work in progress. But with the chassis and add ons essentially complete I thought I time that the bot got a make over. So, it was off to the booth for a spray tan..


(the bot’s gone all Essex)

I *really* wasn’t too sure about the colour from the moment I started spraying. I was also concerned about paint getting in although I had been exceedingly careful in making sure every tiny hole was sealed first.

However after 3 days and 5 coats of paint and 3 coats of lacquer (and a very very stinky house!) I was rather pleased with the end result.


(sHazBot is born!)


(in skittles mode)

Final tuning and Practice.

So, this is it – 7 days to go! We have a bot that is ready to compete in all challenges. There are some final tweaks to the code to complete. I am also heading off to the local sports centre this weekend so I can use a badminton court for practice as I don’t have anywhere really large enough at home.

I still had room for *some* practice though….


After many weeks of building it is weird that the build is complete, sHazBot is sitting next to me and just looks like she’s itching to get started.

My personal Pi Wars timetable arrived earlier this week which made it even more real – my first event is straight into a Pi Noon battle!  I am Battle 1 – Round 5.

It is also Cheltenham HackSpace open day and Cotswold Pi Jam today – that combined with Pi Wars and the incredible Pi Zero has made for one busy week!

See you all in 7 days!! – Good luck to all the competitors and thanks to Mike and Tim for their organisational skills yet again.

Leave a Reply

Your email address will not be published. Required fields are marked *