# What does the number of teeth in a gear determine (when meshing identical gears)?

Suppose I want to mesh two identical gears (size and number of teeth). What would be the difference if both had 12 teeth versus both having 48? Assume the motor spins at the same speed in both scenarios.

So, assuming that the more teeth that there are, the smaller the teeth become (and logically for gears with few teeth, the bigger the teeth are):

Big teeth:

• Capable of handling higher load
• Capable of transmitting a greater force
• less likely to strip
• less precise
• greater tolerance
• more sliding friction1
• greater backlash
• Less smooth movement

Small teeth:

• Less load capable (for a given material and gear thickness)
• Capable of transmitting a lesser force
• More likely to strip under heavy load (for a given material and gear thickness)
• More precise
• Tighter tolerance (more susceptible to defects, and misalignment, in the drive train)
• Less sliding friction1
• Less backlash
• Smoother movement

Data summarised from Does the size of the teeth on a gear really matter?

1 Although, in the case that you describe, with a 1:1 ration the gears will be more geometrically perfect, and friction should be minimal

• What about something like a can opener? Though there are few teeth, they are thicker...i.e. the teeth didn't become smaller... Sep 2, 2018 at 23:51
• Precisely, few teeth, therefore higher load bearing capacity. Ah, sorry, I see a mistake right at the top of my answer... sorry I meant fewer teeth, means bigger teeth, and more teeth means smaller teeth. D'oh! I have now edited and corrected my statement. Sep 3, 2018 at 8:55