Greetings. I am building a board game that utilizes time travel by means of a compound gear train. Each gear will represent a different unit of time, and I would like an idler gear in between so the time gears all move clockwise/counterclockwise at the same time. The units I am using are day (7:1), week (4:1) month (12:1) year (10:1) decade (10:1) century (10:1) millennium (10:1) myriad (10:1) centium (10:1) age (8 teeth).

The ratios put together are 7:1, 4:1, 12:1, 10:1, 10:1, 10:1, 10:1, 10:1, 10:1, 8:1

So here is the issue I am having. I don't want to have any of the gears have odd-numbered teeth, and I don't want massive-tooth gears (none above 60), and the smallest amount of teeth I want on any gear to be 8. I was trying to avoid having to use pinion gears but it looks like I will have to anyway. What is the best setup for this gear train?

What I have for starters is the day to week ratio which will be a compound gear, either 10:20 and 8:28 or 8:20 and 10:28. It gets tricky for me to calculate after that because of the next 4:1 ratio. I also tried started working backwards from the age gear (8 teeth) too but didn't make it very far.