Pi Wars week -30: Turning wheels

As everyone knows, or should know by now: Monday night is Hitchin Hackspace night. That means time to head down, fire up the soldering iron, make a cuppa and do some wiring. My proper motors had arrived in the post so tonight was the first opportunity to test them out.

First order of business was to 3d print some horseshoe-shaped brackets to mount the motors to the base plate I'm using for a test chassis.

motor mounts Or Omega-shaped, depending on your perspective

Next, cursing my forgetfulness in not bringing my Dremel, cut out an opening in the Pi case for the GPIO ribbon cable so the Pi and breadboard could be stacked together on the chassis.

Finally, cursing my forgetfulness again for not bringing wire strippers, I made up some comically oversized cables to wire the new motors to the motor drivers. I'd previously had these motor drivers being controlled from code on the Pi, but using generic yellow right-angle gearbox motors which were so electrically noisy they'd make the driver boards go into failsafe mode almost as soon as the wires touched. Soldering two capacitors apiece to the motors made very little difference, and the cheap-ish 500RPM geared motors I bought were apparently notorious for electrical noise, but as soon as they were wired up they started turning beautifully. Chalk up a success for the parts cannon.

spaghetti Click to embiggen

This shows the unholy jumble of wires making everything run: DC power supply leads crocodile-clipped to the XT60 connector on the power distribution loom, feeding the 5V DC converter that powers the Pi and the motor drivers through 4mm bullet connectors, which then feed the motors through some crimped-on bullets (mostly because I wanted an excuse to use my new set of crimp terminals).

Bad electrical connections are a recurring nightmare, so for a more permanent solution I may 3d print some motor mounts with hard-mounted connectors that the power wires from the drivers can clip to and not pull on the relatively delicate motor terminals.

Now I know the motors are OK electrically, it's time to bite the bullet (connector) and start mounting things to the base plate so this whole spaghetti mess can start driving itself around.

- PKM