My Engineering Projects:
Nerf Crossbow, Nerf Automatic Crossbow and LARP light-up Foam Sword
Nerf Crossbow
I decided to make this crossbow as a massproduceable but unique gift. I have many friends who do Live Action RolePlay (LARP) who would enjoy a crossbow.
I already have a lot of crossbow bows left over from another project, so it would be a good way to get rid of them. The basic idea is I need a channel for the dart to go down and a trigger to lock the string in place when pulled down. Additionally, I need a flexible piece to hold the dart in place before it is launched. In designing the bow, I wanted to make it look nice while reducing the total amount of plastic needed. I started early on with many curves. These curves also reduce mass, as the crossbow does not need to be a rectangle to be structurally sound. In making this, I found many issues that needed to be addressed.
I have had some trouble seating the bow in the front, and my initial attempts to secure the dart wound up in the arm breaking. I ultimately made the arm removable and reinforced the point where it kept snapping. To secure the bow, I plan on using weather stripping as a high density padding to keep it from moving, while still wrapping the whole front in construction string. Below you can see renderings from my design tool as well as numerous iterations of the crossbow body as I worked to refine the design – subtle changes that affect how it feels in the hand and how it works.
Nerf Automatic Crossbow
The cool thing about this was learning how to design in 3D – this was one of my first projects.
I taught myself how to use several 3D modeling tools that produce files that are printable by 3D printers. This, by itself, was quite an adventure.
I designed this crossbow in several pieces that are held together with screws and so each piece had to not only exactly fit the other, but also accommodate the screws.
Just right of my thumb you can see my logo (better shown above on the Nerf Crossbow end). This project uses an existing Nerf magazine to feed Nerf darts to the crossbow, making a sort of rapid-fire crossbow.
From this perspective you can see the entire nerf Automatic Crossbow.
LARP Light-Up Foam Sword
My Live Action RolePlay group (LARP) has a medieval theme (Ancient Order of the Knights Pendragon) and I’ve been having fun designing and making “armor” and “swords” for myself and my friends.
This is my latest creation.
To research this, I needed to source clear PVC, and find a battery that could be held in the handle rather than externally. I have experience working with PVC from having made hundreds and hundreds of mini-marshmallow blasters out of PVC. What was specially fun for this was finding the foam component that would allow light to shine through.
In the photos below you can see how the components looked before I assembled everything.
