Braainado: An over-engineered BBQ fan

Jayd Lawrence -

Whats in the name

The name Braainado comes from the Afrikaans word "Braai" which means barbecue or grill and the word tornado. I thought it was funny. ¯\_(ツ)_/¯

The idea

So, being the South African in my friend and church groups, it normally falls to me to do the barbecuing when ever a summer barbecue is happening, which I honestly don't mind. At least then I can make sure that my food isn't burnt.

Over the last 5 years or so living in the UK, I have made a lot of barbecues. A pattern started to emerge of things that I found frustrating about doing barbecuing:

  1. Getting the coals going required blowing on the fire or fanning it by hand, which was exhausting
  2. Smoke getting in my eyes while I was cooking

I originally set out to solve the first problem, but my solution would probably work for both.

I had seen hand cranked barbecue fans before, but they always seemed to break, and then it is still a lot of effort, it is just more efficient with your effort.

So I knew I wanted something that was self-powered.

I began thinking about DC motors and 9V batteries, but then I remembered that I am a drone enthusiast, I already have access to Lithium Polymer (LiPo) batteries, Electronic Speed Controllers (ESCs) and brushless motors.

So the idea was born.

Proof of concept

At the start of a barbecue at my house, we held my quadcopter about 60cm above the barbecue and gave it full throttle, the idea seemed to have merit, so the project began.

The parts

The basic plan was to hook up a brushless quadcopter motor with an attached propeller to an ESC and have some mechanism for turning it on or off.

The tricky part is that ESC's don't just come on when you turn the power on, they use the same PWM signal as servo motors, so I would need something that outputs PWM.
My first thought was an Arduino Nano. I still had a load of cheap Chinese knockoffs of those lying around and I knew you could control servos with it.

I needed to power all of it. I have LiPo batteries as well as some 18650 Li-ion cells. I went with the 18650s since they are thought to be less prone to explode than the LiPos and are in general easier to maintain.
I also needed some sort of 5V regulator to step down the voltage that goes to the Arduino.

  • Electronic speed controller (ESC)
  • Brushless quadcopter motor
  • Propeller
  • Arduino
  • 18650 Li-ion Cells
  • 5V regulator (built into the ESC I had)

The Code

I played around with the servo libraries on Arduino for a bit but I could not get them to reliably talk to the ESCs. Most of the time the ESCs would refuse to do anything.
I shelved it for a few days and when hanging out with my friend, Chris Dell, one evening and I mentioned that I was having issues with controlling the ESCs. Chris took it as a personal challenge and with a bit of Googling and a lot of tinkering, he managed to figure out the handshake that the ESCs look for on startup to make them work.
Once the handshake was sorted, the rest of the project was pretty straightforward.

The code is not particularly complicated, other than the weird handshake in the setup function.

Some notes:

  • Once I had started messing with the Arduino side of things, it became apparent that being able to modulate the speed would be handy, so I added in a potentiometer into the mix halfway through.
  • Using writeMicroseconds instead of outputting in degrees was helpful as it gave more precision and also we had an idea of the PWM timings from calibrating the ESCs for use with our quadcopters

The housing

My original plan for the housing was to turn it into a ducted fan like some sort of backwards trumpet.

I could 3D Print this part and get the most power possible out of my motor.
But after thinking about it for a while, I started to suspect that it might melt near the fire and the motors were so powerful, that the ducting was ultimately unnecessary.

What else could I use?
Then I had a crazy idea. How about a gun, that shoots air...

So I decided to mount all the parts to a piece of wood so that it looked a bit like a rifle.
I found a picture of a rifle online, found a plank of wood, drew a rifle outline, cut it out with a jigsaw and attached the parts.

Bam!

The Braainado was born.

The Arduino on some prototyping board.

A bit of folded metal to act as the motor mount.

A helpful dial on the potentiometer that I got from Thingiverse and 3D Printed to makes it easier to adjust the speed.

On/Off switch mounted where the trigger would be on a rifle.

The Li-ion cells that power it all.

A short video demonstrating the Braainado.

Overall I am very happy with the Braainado.
It is over the top but it is very effective for starting barbecues and is actually the most practical of my crazy projects to date.