This may be simple to some, but this is my first experience with designing gears, so bear with me... I'm trying to "cut" a spur gear to match the profile of the pinion gear I designed. This gear won't carry any load, it's basically for esthetics, but I want good contact between the two gears. I have an 8 tooth pinion & 60 tooth spur gear. Here is my pinion gear: I am working with one tooth profile and trying to simulate it moving out of the mating gear. Seems simple enough... This is the shape of one tooth, and the line/arc segments are something I drew that approximates what I should end up with (I used the assembly and adjusted the points until it was close). I could just use those line segments, but I really want to figure this out mathematically. This is what I figured should be right, but obliviously it's not... -I drew a circle around the main gear with a radius of the distance between my gear shafts. -Keeping the center of the pinion gear tooth coincident with that circle I rotated it 5 degrees (I plan on making this increment smaller once I get the calculation figured out). -Then I rotated the tooth around the center of the spur gear at the increment that it would rotate if the pinion rotated that 5 degrees. That was .6666666667 degrees. My math: 60 tooth spur - 8 tooth pinion 1 rotation = 7.5 rotations 360 degrees = (360 * 7.5) 2700 degrees 2700 / 5 (sketch increment) = 540 360 / 540 = .666666667 I'm sure Iâ€™m over simplifying this because here is my result: The red line is the line/arc that represents where I should be. I know it's really cluttered, but I figure once I get this figured out I can just use this file as a template. So obliviously .66666667 is too much of an increment. Just playing with the numbers I found .59 is really close to what I need. But I don't know how to get there mathematically. Does anyone know if I'm just completely over simplifying this, or am I doing something wrong in the math???? Please help!! Thanks, Bill Not sure if it will work but I also attached a .gif depicting what I'm trying to accomplish.