This week I sat down with a pencil to figure out all these tangled mechanisms.
Yes…a pencil. That’s my big fancy tool. Creating these mechanisms is, above all, a design process for me. No CAD or solidworks. Just lots of drawing, re-drawing, and refining. I use the light table and a protractor to look at the levers in different positions of their amplitude. This is to not only check that they don’t run into each other, but also look at the shapes to see how they visually interact. It’s a sort of back and forth balancing act that hopefully leads to a mechanism where all the shapes and angles look good and flow together, no matter what position everything is in.
The drawings piled on this disaster of a work surface include:
-The lever that works off a cam on the hour-hand, clicking a 24 tooth ratchet once an hour. Almost everything works off the rotation of that 24 tooth wheel, so things are very mechanically busy in that area.
-The great lever. This controls the calendar hands, telling them how many days to jump forward. Also attached to this lever is an arm with gear teeth on the end of it, which moves the gear train of a drag-fan that slows and softens the action of the mechanism.
-The day click. This simply bumps the hand for the day of the week forward one click with each rev of the 24 tooth wheel
-The moon-gears. Of all the drawings this one looks the simplest, but it’s actually kind of interesting and unique (for me) to this clock. In order to make the moon as big as it is, I had to make the moons span the entire mechanism. The four moons will rotate inside of a giant gear that spins around the center axis behind the whole perpetual-calendar dial. Those gears work off of the 24 T ratchet, reaching out and down through the front plate to engage with the big moon gear.
I’m admittedly not very good at explaining this stuff with type. It’ll be easier once it’s made and I can show pictures or video.
Next I have a few small clicks and stops to design, and then I have to design the bridges that hold all of these mechanisms in place.
The great-lever & drag-fan arm.
The day-click.
The lever & click that advances the 24 tooth ratchet wheel.
The moon-gears