Simple Catapult

thingiverse

A small, simple catapult that uses a rubber band to fire superballs. A suitable project for teaching basic ballistics or just for fun. You will need: One (1) Rubber Band, preferably a thick gum band Superballs (small rubber balls appr. 2cm in diameter) You will need to print One (1) cat_arm.stl One (1) cat_spacer_rb.stl Two (2) catapult_wall.stl Three (3) cat_spacer1.stl instructions1.pdf contains basic instructions for construction and use along with diagrams. Text instructions from that file are copied below. Sorry if they're insultingly simple. They were written for a friend with the mechanical skills of a drunken chipmunk. Construction 1) Lay one Sidewall flat as shown above. 2) Insert the axel of arm into the matching hole in Sidewall (red dot), ensuring that the ammunition basket faces right when the arm is perpendicular to the base. Rotate arm counter-clockwise until it is between red and blue dots. 3) Insert the retraction base into the matching hole in Sidewall (green dot). 4) Insert the spacer braces into the remaining holes in sidewall. 4) Ensure that all parts have been securely inserted and snapped into place. 5) Align other Sidewall so holes match up with posts of arm, retraction base, and spacer braces. Press carefully to lock into place. 6) Fold rubber band around retraction base outside of securing rings so a loop is formed. 7) Extend loop around mechanism channel on arm.