Gear first steps

I would to learn about Gears. Build a Plate with two Pins from
Pin Connectors V3 (Tony Buser), Modified by Emmett Lalish.
I define the Distance between the two Pins to 50mm.
Define two Gears.
A Gear 1 with 10 Teeth.
A Gear 2 with 6 Teeth.
Calulate
r1 + r2 = 50mm
r1 / r2 = 10T / 6T
give r1 = 31.25mm and r2 = 18.75mm
Modul = 6.25 (2xr/T = 2x31.25mm/10)