Parametric Cantilever Spring Test Sample

thingiverse

Measure the properties of a cantilever spring in a plastic mechanism by following these steps: 1. Design your beam in OpenSCAD, or use the provided .stl file with dimensions l=80 mm, w=10 mm, and h=3 mm. Convert it to Gcode using your preferred software. Note that object infill, number of shells, and other options can impact results; print following the length for best results. 2. Print the part using your favorite printer. 3. Test the part using a clamp, ruler, and force sensor. 4. Calculate Young's modulus (e) by measuring the force required to deflect the tip of the beam slightly without causing warping or breaking it, using the equation: e = (4 * f * l^3) / (x * w * h^3). 5. Determine yield strength (Sy) by measuring the force needed to permanently deform the beam; use the equation S = (6 * f * l) / (w * h^2) to calculate base strength according to the load. 6. Measure ultimate strength (Su) by breaking the beam and noting the force used, using the same equation as for yield strength but with the understanding that results may not be entirely accurate due to deflection needed to break the beam. 7. Repeat steps 1-6 with different designs to maximize your results until you're satisfied. 8. Design a real part and recycle plastic from broken parts if possible. 9. For the provided .STL beam, printed on TOM HBP with MK7 using White ABS from 3dprinterstuff.com, layer height of 0.3, one shell, 100% infill, and feedrate of 30, the results were e = 1.1 MPa ±10%, Sy = 1.9 MPa ±15%, and Su = 4.7 MPa ±20%. Happy experimenting!