Before reaching the launcher, the flame activated powder cartridges must first exit the main unit which stores them. On this page are a series of tests dedicated to finding the most practical solution.
Test 1
- Hypothesis: By rotating a stationary piece of studding, a nut that is unable to rotate will rise upwards. A plate attached to the nut will lift the cartridges towards the cartridge launcher. By using M16 (pitch 2mm) studding, 20 rotations will be required to raise one cartridge (diameter 40). The motor rotating the studding will need an RPM of 2,400 to release two cartridges per second.
- Application: A plate was laser cut from MDF and a nut was attached. Stationary rods (to stop the plate from rotating) and centre studding were attached to a large card board tube base. The studding was rotated by hand.
- Outcome: The hypothesis was correct, however there are some issues. Turning the studding by hand requires a lot of force due to friction. This means a heavy duty motor will be required. This increases cost. Also, at the end of the process, there will be some cartridges that don’t reach the launcher, as there are no cartridges below them to push upwards.
Test 2
- Hypothesis: If the cartridges are allowed to freely fall through a funnel into the launcher, there is a risk of them getting stuck.
- Application: A paper cone was attached to a 150mm diameter drum, filled with ping pong balls. The balls were allowed to fall freely. The test was completed multiple times.
- Outcome: The Hypothesis was correct, the ping pong balls did get stuck at the exit. The unit was shaken and vibrated to overcome the issue but it still did not work. The solution that did work, was cutting a small hole in the back of the unit and moving the ping pong balls around with a pen. This method of using a ‘cartridge disturber’ will be used in the final product.
Application Of Prototyping In Final Product
The flame activated powder cartridges, highlighted in blue, fall down into the cartridge funnel (part 49) highlighted in green. This funnel directs the cartridges into the exit point. To stop the cartridges from becoming stuck, the disturber stick (part 47), highlighted in yellow, is constantly rotating as a result of the attached stepper motor (part 25) highlighted in red.
