How To: Gears

Basic Properties 4140 Steel (Annealed) 7075-T6 Aluminum 6061-T6 Aluminum
Density 0.283 lb/in³ 0.102 lb/in³ 0.0975 lb/in³
Tensile Strength (Ultimate) 95 KSI 76 KSI 45 KSI
Tensile Strength (Yield) 60.5 KSI 67 KSI 40 KSI
% Elongation 26% 11% 12%
Weight Compensation 1.000 lbs 0.358 lbs 0.310 lbs

Sources: McMaster Carr & MatWeb

WCP uses 7076-T6 to provide lighter gears than steel (~1/3 lighter), while still being stronger than 6061-T6 Aluminum.

General Gear Information

  • Gears are normally 0.500" wide (Unless otherwise specified)
  • Gears have a protrusion, a tiny nub on both sided of the gear (Unless otherwise specified)
  • Gears will come anodized (Type III), used to harden the gear and prevent corrosion
  • Gears will have teflon coating on them


Installation Notes

  • The nub is designed to butt up against the face of a bearing, this eliminated the need for a spacer and reduces part count
  • WCP highly suggests using DuPount (Dry-Grease) for lubrication. McMaster #8710T35


  • The normal recommended rule of thumb for FRC robots is +.003 spacing between gears
  • These gears have a modified tooth profile to compensate for anodizing.

WCP recommends:
For a single stage gearbox (custom): +.000 - +.001 backlash
For any other gearboxes: +.002 - +.003 is recommended.