This instructable is very similar to my last one, and it shows a different placement of nine gears this time with different number of teeth. I also made an handlebar so that a child can keep it while he turn the gear.
Step 1: Software
I used the same software of before, so you can read some better explanation on my other instructable. Anyway I just remember you to keep the same value of Diametral Pitch for all the gears and only change number of teeth. Then save the files one for each gear and open them in your CAD software.
Step 2: Some Adjustment
Then in CAD remember to draw a circle with diameter equal to Pitch Diameter value. When you place your gears on the board I suggest you to leave a little space between these circles, maybe 0.3-0.5 mm, so that you are allowed to make a little mistake in exact measurements and cuts.
Step 3: Lasercut at Your Favorite MakerSpace
I cut my 4mm plywood at WeMake makerspace in Milan, with a 80Watt laser machine, but you can easily cut this thin plywood with a smaller one. I obtained very nice gears almost ready to assemble. If you don't have a near Makerspace where to use a lasercutter, you can print the gears on a paper sheet and glue it on the wood board, so to cut it with jigsaw.
Step 4: Some Detail
I only had to make a seat for screw heads and find some metalware. Also is better to sandpaper the surfaces, and paint them if you wish.
Step 5: Cut the Board
If you want a unique shape for the board, you can follow the contour of the gears. As you see I also added an handle and I engraved the name of my little nephew.
I cut three different shapes and then glued them one each other, to obtain a little more thickness to screw in the pivots.
Step 6: Almost Complete
With a gimlet enlarge the screw holes as much as you need, just not too much. Then make an hole to screw in the handle to turn the main gear is the bigger one in my case). I used a metal spring so that you can turn the gear with no friction under your fingers.
Step 7: Start Assembling
Finally you can assemble every gear in place. Place tho washers between each gear and the base, to help them to turn with no friction. Maybe you will have to sand some part of the gears if they struck each other.
Step 8: You Made It!
Here it is! Your nephew (you) can enjoy turning one gear and calculating the ratio between them ;-)