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|
|Weight Comparison||1 LB||.358 LB||.341 LB|
-Sources: McMaster and MatWeb
-WCP uses 7075 - T6 to provide lighter gears than Steel (about 1/3 the weight) , but still decently stronger than regular 6061 Aluminum.
General Gear Information:
- Gears are normally .500" wide (Unless otherwise specified).
- Gears also have a protrusion, a tiny nub on both sides of the gear (Unless otherwise specified).
- Gear will come anodized (Type III), used to harden the gear and prevent corrosion.
- Gears will have a teflon coating on them.
- WARNING: DO NOT RUN GEARS WITHOUT GREASE.
- The nub is designed to butt up against the face of the bearing, this elimates the need for a spacer and reduces part count.
- WCP highly suggests using the grease mentioned below:
- DuPont (Dry-Grease) - 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.