Science - Testing gears with different pressure angles

This was for a SRP [Student Research Project] for science class. Need vice and torque wrench (wrench head 1.5 inch x 1.5 inch). Pretty straightforward assembly, put the torque wrench head in the big gear then shove the rest in a vice, start at lowest torque and go up by 5 until gears brake. Bigger pressure angles should yield higher strengths, for me 25 pressure angle was stronger for some reason [one trial broke at 75Nm]. Lots of infill and perimeter are needed so the inside of the gear holding the torque wrench head doesn't slip. Frame can be used to test all sorts of gear sets for strength.