Compact Springless Firing Mechanism
A simple, compact firing mechanism design.
There is a well-known phenomenon when pushing a LEGO pin out of a pin hole: as the pin is uncompressed, some energy is released that causes it to “fly” a short distance. I’ve used this effect to build a very compact firing mechanism that doesn’t use a spring in order to reduce the size and to minimize the stress for the motor.
Building instructions available here: sariel.pl/downloads/
The mechanism works by simply pushing pins out of a beam. I’ve used simple 1×1 pins but other pins can be tested possibly with better range and impact. The addition of 1×1 beam on the pins is necessary to keep them aligned with the mechanism, as the pin itself has a diameter smaller than the inner diameter of a pin hole. The mechanism can be optionally fitted with a barrel, also included in the instructions. The main issue with this sort of a mechanism is low range and low impact. It can be solved by using a shock absorber, just like in my T29 tank’s firing mechanism.
Video:
