I freely admit that there’s no need for this thing to exist. The world doesn’t need an absurdly complicated electromechanical calendar. I made it just because.
As you can see, It shows the current date by moving engraved tags attached to chains. It does this by turning the sprockets the chains run over to the correct position. The tags move into position for a new day the first time after midnight that the device detects the presence of something big – like a person – moving nearby. I made it do that so I could see it move each morning.
Behind the scenes there’s an Arduino attached to several things. A realtime clock with battery backup (to keep accurate track of the date and time, even if the power goes out); to a passive Doppler microwave sensor (to detect people); and to two tiny, geared stepper motors, one for the day and one for the month (to move the chains). All the non-electronic parts, except for the brass weight at the bottom, were made on the Glowforge. That includes a set of planetary gears needed to get sufficient torque to move the months chain.
I learned a lot about the shape of sprockets and involute gears. And how chains go together.
The “rollers” in the links are lengths of small diameter dowel, all cut to length in the GF. The chain parts are all press-fit; no glue. That this worked perfectly is a credit to the accuracy and repeatability of the GF.
And here’s a view of the weight assembly at the bottom:
Simple printed calendars are more useful and more functional, no doubt. But I like it anyway. And I get a kick out of it jumping into motion when I see it each morning. Especially on the first of the month.
That was artistic brilliance. And yes, there is a need for absurd solutions to things that already have commonplace ones - if only for the whimsy it adds to the world.
I bet no one who sees this in action gets the same feeling of joy when they walk by a clock or paper calendar
I am stunned! That is absolutely one of the most impressive, imaginative things I’ve seen! And the fact that you made the actual chain on the GF blows my mind! Great job!
That’s my kind of calendar; it would fit right in w/my kitchen. (Though the only part that moves is the Cat when I catch him on the countertop. Person Arrives = Movement)
This is awesome!! I was working on some similar chains, but I had issues with the chains getting caught and not sliding properly on the sprockets. Have you experienced this issue, or found a way to overcome it?
Looking at your sprockets again, it appears you have sanded down the tips to try to reduce this issue?
No, the plans aren’t for sale (or give-away) only because upgrading them from “something I can make 'cause I know how it’s supposed to go together” to “something someone else can build” would be a bunch of work. Sorry.
It took about two weeks, on and off, mostly due to design revisions as I went along. For example, I had to rework the month chain moving mechanism by adding a planetary gear reduction to give it more torque. As you can imagine, the most time consuming part was assembling all the chain links. I got very good at that simple but repetitive task.
Yours is awesome!
