In any case pick a book on mechanical engineering for the really gritty details.Īs it is now i think this over exceeds the purpose of this exchange. But this was a very short version of my introductory lecture on the subject. As you need to calculate the shift and size for the mirror of this curve to get the teeth aligned. (If you graph 0 to - Pi/2 you get the same image).

Where t is the angle in radians and r is the radius This in mathematical parametric terms forms a function for x and y as for example as follows, you get the following parametric function: x = r * sin(t) - r * t * cos(t) Image 1: Formation of the involute shape. Vector 2 is perpendicular to this vector and is the length of how far has been traveled on the base circle. Vector one is rotating along the base circle that the curve is the involute of. The involute shape is simply the sum of 2 vectors. This is because the pair of a circle involute is a circle involute. In principle you could generate a corresponding gear shape pair for nearly any shape but in practice involute has superior properties for misalignment. The most common being the involute of a circle and the cycloid. There are several kinds of gear functions. This may be out of focus for GD.se but i will try to birefly explain this. Therefore, your small gear should use circles of 250 and 450 in diameter. So your small gear should be 350 in diameter with the tips and bases +/-100 in diameter. So for the big gear where the two circles are at 600 and 800 diameter, your pitch circle is 700 in diameter with the tips and bases +/-100 in diameter.

(In properly designed gears for minimal noise and backlash, etc., there is a complicated formula to determine where to position the pitch circle and how to contour the teeth accordingly-see answer.) You can just put it halfway between for your purposes.

The pitch circle is somewhere between the tips and bases of the gears. The dimension that should be cut in half is the diameter of the 'pitch circle'. Instead, the bases and tips of the teeth need to be the same distance away from each other in both sizes of gear. Your teeth do not have the same depth as each other because you are simply cutting all your dimensions in half. I won't bother going into the details of a properly engineered gear, but just how to get yours to 'look right'. I'm not a graphic designer or user of Illustrator, but I am a mechanical engineer.

Svg gear generator