More last-minute redesigns

Its always funny that however much you plan and design digitally, you still find issues when putting it all together.

In this case I’d been working to assemble and test the nerf gun on a fake “bot front” – a duplicate of the front parts of the robot where the accessories connect to it, bolted to a wooden board. It seems the hexagonal axle I’d designed to mount the gun to the robot were not long enough. OK, simple enough fix in CAD, and reprint. The axle halves were then epoxied together and fitted up to the robot. And now we’re not getting enough friction from the press-fit “cup” at the end of the axle to the servo output shaft.

This time the fix was to create a separate cup that screws down onto the servo shaft for a tight and reliable fit, with a hexagonal cutout to put the end of the shaft into. Which fitted perfectly onto the original, too-short axles.

Here’s a shot of the front of the nerf gun on the test stand. The cup is behind the motor cable right at the centre of the shot.

And while we’re here, here’s a side view of the nerf gun on the test stand:

Here you can see the Pi, the gun-mounted camera and the PCA9685 servo driver, which we talk to over I2C to set servo positions.

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