Single Piece Desktop Catapult

thingiverse

Somebody I worked with picked up a little plastic catapult made by Stratasys out of Ultem while at a conference. This is a similar catapult based on the same principles. It prints as a single piece and uses torsional windup of the the throwing arm axle as a spring. The second arm holds the throwing arm in the ready position and acts as the trigger. It can launch a small ball of paper quite a distance. Intended for PETG and other relatively stiff but yet elastic (not brittle) materials. This is a bit of a work in progress as I tweak cross sections and such. Print Settings Printer Brand: SeeMeCNC Printer: Rostock MAX Rafts: Doesn't Matter Supports: Doesn't Matter Resolution: 0.25mm Infill: 25% Notes: I expect PLA and ABS will only give you a handful of uses before breaking with this design. Instead, I use PETG and so far I have been able to get over 100 uses without any damage and only minor permanent set (arm resting position has rotated maybe 10 degrees). I expect nylons would also work, although the spring force may be rather weak with the geometry I chose. There are two ways to print this. The first is to use removable supports for both arms, which I personally have not tried. The second method is to cut off the first 1mm or so of the model (I use the z offset option in Simplify3D) so that all pieces are touching the build platform.