According to legend, the repeating crossbow was designed by Zhuge Liang, a person of great wisdom and resourcefulness in Chinese folklore, and the drawing and the actual object were already lost. Later generations designed several repeating crossbows based on the descriptions in ancient books. In this article, a repeating crossbow was replicated using Makeblock parts in accordance with one of the above designs.
There are three major components of the crossbow body:
1.The arrow groove, in which several branches of arrows can be placed and an inverted-L string slot was in the end, is the core feature of the crossbow.
2.The crossbow body, which serves as a support. 3.The poll rod, which plays a role in pulling the string and shooting the arrow. After putting enough arrows in the groove, push the rob, which is similar to load a gun. Arrows will fall to the launch slot due to the gravity and the string will be hung to the corner of the inverted-L string slot.
When the load is completed, pull back the rob and the inverted-L slot together with the string will be tensed backwards. When reaching the limits, a structure among the string hanging position will drive the string out to complete the cocking.
Details of the arrow groove are shown as below. Among it, B represents the crossbow string, D is arrows and E is the groove shell.
Three steps of the continuous shooting:
When understanding the mechanism, then you can make it. First is the arrow groove which is simply a patchwork of parts including double-hole beams and please note that you must create an L-shape slot.
Next, you can build the crossbow body and the pull rob on the basis of a high strength square beam. Please replace the middle section with metal materials since there will be repeated friction between the string and the arrow groove.
And then, please make some arrows. There was no appropriate material in hand, therefore using some 3D printed long strips of arrow instead.
Finally, assemble all these parts and fill in arrows.
For security testing, we use rubber band with small elasticity coefficient. To enhance the power or increase the range, the string pulling distance and the string material can be exchanged, as well as the crossbow arms can be replaced with composite materials or the spring steel.