Trebuchet MECH 3800 Final Project Kurt Wiessmeyer The

Trebuchet MECH 3800 Final Project Kurt Wiessmeyer

The Idea • Create a scale model of some sort of machine or device • Trebuchets are ubiquitous and straightforward, and can easily be scaled down • Similar projects have been done, but all of them use non-3 D-printed slings • My goal was to create a model based on these criteria

Test Prints • Main focus was on the sling and bracket components • Needed to check if the “pocket” could hold the projectile—a Skittle • Changed the width of the arm and the release angle • Test prints gave an idea of the tolerances between moving parts

Lessons Learned • Tolerances are different in X-Y planes compared to Z plane • Round components had less clearance in certain areas than others • Lots of open space leads to increased costs • High build volume with lots of open spaces will require lots of support material • There a lot of calculations behind trebuchets • Ideal ratios between projectile/counterweight, long arm/short arm, etc.

Failures • The sling component does not work consistently • Requires the Skittles to be slightly squished in order to stay in the pocket • Projectile does not always release at the correct angle • Optimal angle would be 45° upwards • Actual launch occurs from 0° (vertical) to 45° downwards

Successes • The motion of the entire assembly works properly • Each part moves in the same manner as a full-size trebuchet • Good tolerances between parts • Smooth rotation within consolidated assemblies • It looks cool • Good surface finish on each component

The Finished Product

Final Print Results/Budget • Overall success Budget Breakdown: • Frame/Arm/Sling: $73. 95 • Stratasys Fortus 450 mc • Counterweight: $42. 49 • Stratasys J 750 • Trigger Pin: $14. 96 • Desktop Metal Studio • Total Cost: $131. 40 (fake money)