A version of Leonardo Da Vinci's catapult design

thingiverse

A friend recently showed me a box containing a wooden kit for making a model of Leonardo Da Vinci's catapult that they had bought for one of their grandkids. That was when I first learned about his design. It looked to me like an intriguing 3D printing project, and after doing some research on the internet, this is what I came up with. I've scaled down the catapult to accommodate indoor (or practice) golf balls. As you can see in the photos, I designed three different 'Side LH' versions offering varying angles of elevation. I prefer the steepest one and it gives a good trajectory when the catapult is on the floor. Designed using Moment of Inspiration, and printed entirely from PLA on an Original Prusa i3 Mk2. The screws used are all 3mm x 10mm long mushroom head cap screws. A video of the catapult in action can be found here: https://youtu.be/rkfbdhpfBn0 Print Settings: Printer: Original Prusa i3 Mk2 Rafts: No Supports: No Resolution: 0.2mm Infill: mostly 10% Notes: Material PLA. I experimented with different infill percentages for the springs. The ones shown in the video are 100% solid, but I think a 50% infill works nearly as well. By the way, I tried making the springs from ABS - PLA turns out to be better. For all other parts, I used 10% infill. Post-Printing: Take care when setting up the ratchet assembly and arm. Leave final positioning of the arm on the 'splines' until you're happy with the string/spring setup. With the springs straight, the screws around which the string runs should be horizontal, and located on the side of the shaft farthest from the corresponding spring. Then the arm should be tightened in the 'fired' position. You'll likely need to do some further fine-tuning. How I Designed This: I found some images of Leonardo's sketch online and then 3D designed using Moment of Inspiration (Moi).