Pi Wars Week -28: A career in modelling

The story of this week has been CAD, CAD and more CAD. I realised that the "stick it all wherever it fits" approach I used while testing hardare wasn't going to cut it for the final layout. There's a lot of pieces to fit in a small space, so the sensible thing to do seemed to be make a CAD model where I could move everything around until a realistic layout emerged.

Having leaked my design on Twitter enough times that there's no "big reveal", and having submitted my proposal so Mike and Tim know I came up with the idea, I guess now is the time to unveil the concept. So, I present...

Reliant Raspberry

the shell

My elevator pitch was "Reliant Regal ambulance". This came about because

  • I'd always wanted to do a classic car-themed build
  • I like building three wheelers with a castor at the front
  • and because a three wheeler ambulance seemed like a way of engaging with the theme without going too gritty or too Thunderbirds.

Yes, Reliant Regal - the Robin is the later version, this is the Supervan model Regal (as seen on Only Fools And Horses). I'm taking some liberties with the design here, like the Rialto-style rectangular headlights.

I started 3d printing a complete shell, but on realising that the side panels were going to take five hours each I stopped after just printing the bonnet. Possibly I need a faster printer. Then while those extruded I modelled all of the individual components and got them arranged inside the shell.

cad cutaway

What is it they say on YouTube... "no copyright infringement intended"?

For the time being while I work on wiring, I decided to keep the "breadboard on top of Pi case" arrangement which would let me fit the Pi and much of the wiring amidships, leaving the front free for sensors and the rear for power electronics and motors. The height of the shell also gives space to put in a "mezzanine" shelf which will probably hold the battery and accessory electronics like the Arduino Nano to power the blinky lights and challenge-specific attachments.

smol prototype

The black outline shows the space available inside the shell... it's going to be a squeeze

The ribbon cable shouldn't be necessary for the final hardware, which I'm planning to build around a proto shield that fits directly onto the GPIO header, but for now it lets me experiment with wiring so it can stay. With luck the next update will be a driving chassis with the right dimensions to fit into the shell. Who knows, maybe I'll even wire up the flashies...

-PKM