It will be peg-board and bolts that thread in from the bottom. Gears will fit in different combinations. Some gears will have features for dialing them into motion like an old phone and others will have groves to attach figurines. Perhaps cardboard ballerinas, hockey players or anything you want to color/paint and spin around.
I did a dry run of two gears to see what they’d be like (and verify the design work). Came out nice but I decide it was too small for a three year old. So I will double the size.
I made a grid and then looked for different ways that circles would fit into the grid. I then made up gears of the same size and axle distance using the Woodgears.ca Gear Generator. A very awesome program.
The challenge is to find gear sizes that fit into the grid in different ways. I started off with a grid of 1.5″ apart. I generated two gears that would span the 1.5″. I wanted to make sure that two of the large gears could span the diagonal of the 1.5″ square. So I changed the number of teeth on the two gears until the large gear was the size I thought I needed. I supposed that if I couldn’t get it then I’d just need to go to smaller teeth.
The grid will be 1/4-20 threaded holes so you just screw nylon bolts in from the bottom. I will counter sink them or make a frame around the border so they don’t contact the table.
In this run, it looks like there will just be two gear sizes (but we’ll see how much time there is).
I’d like to make other versions in the future with more gear sizes and even allow gears to be coupled into pairs like a larger gear and pinion.
This is a big challenge with this sort of project. I’m using polycrylic and acrylic paint on a couple of the gears. The difficulty I’m having is it seems to take a lot of work and it’s very hard to get the surface to be nice.
Lego Gear Calculator