And the spudGunOmeter is ready for it's first live fire test.
The PVC with the red labeling is the barrel. The purple boxes on either side of the spudGunOmeter house LED/phototransistor pairs. The sandwich box houses the 9V battery, display and arduino, along with a breadboard "intermediate frame" and reset button.
When the spud passes the first sensor, it interrupts the beam and a timer starts. When the spud passes the second sensor, the timer stops. The sensors are 1' apart so the muzzle velocity calculation is simple.
Later today, when Grandma isn't around, my grandson and I will start live fire testing.#WhatCouldPossiblyGoWrong