I started this project on my old X-Carve then finished it when I upgraded to a MK1 Longmill. Everything designed in Easel. It was actually quite a challenge, as I wanted the numbers to have flat bottoms and not follow an arc.
Black Arborite glued onto 1/4" MDF. Milled with 1/8" downcut bit and acrylic white paint to fill in the numbers and ticks. A cheap mechanical wall timer is used for the mechanism. It is a bit noisy because of the plastic gears and huge gear reduction inside, but I’ve had this one running for years.
The clock is 23" in diameter. With the single hand it doesn’t tell the exact time, but that’s not the point. I built it to get a sense of the position of the sun. At 12 noon the sun is approximately at its zenith here, and at 0 hour it is on the opposite side of the earth.
I made 2 others for friends with small children.
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When I was scrolling down through the pictures I was wondering “Where do you find a 24-hour mechanism for the single hand?” Seeing the final picture I’m pretty sure I wouldn’t have thought of that. Nice design!
Thank you! I stripped away everything I could from the wall timer and cut a cup out of MDF that just pressure fits onto the blue dial. It’s in one of the photos.
Nice design. I design and build clocks, but have never made a 24hr version. I really like the slightly industrial functional look. Smart using the timer mechanism! I would never of thought of that.
Thanks! I took apart a few of those wall timers to see how they worked. They have a synchro motor that cycles with the mains frequency. 60hz here in North America. The motor turns fairly quickly (I can’t remember the RPM), and then it goes through a pretty large gear reduction to get down to one turn per day. There is a surprising amount of torque at the final shaft, which the wall timer needs to flip the switches on and off.
The blue final drive that you can see in one of the photos also has a one way ratchet so setting the clock is really easy. I just turn the large red hand clockwise to the correct time with my finger.
And here’s another cool thing that I learned with this project:
I glued the Arborite to the 1/4" MDF with contact cement outside in my carport. It might have been in late fall, so pretty cool and humid outside. The MDF was 24" x 24" and it had been outside for a while. When I brought it inside the MDF contracted so the sheet was convex with about a 1" rise in the centre. I screwed it down flat to the spoil board of my machine and did the milling. There are 4 screws on the face of the clock that were strategically placed to hold the stock down flat. They also hold the frame on the back. Since the stock wasn’t perfectly flat I had to redo many of the ticks and numbers with different cutting depths. It looks like a simple project, but it took a lot of adjustments to get it looking correct.
So the face of the clock is slightly convex. You can’t see it in the photos, but it adds a bit of character to it.
