Hidden Shaft And Gears Make This Hollow Clock Go

January 8, 2022 by Donald Papp 20 Comments

[shiura]’s Hollow Clock 3 is a fantastic 3D printed take on a clock movement that uses a hidden mechanism to pull off its unusual operation. The Hollow Clock has no face, just an open space with an hour and minute hand that move as expected. Only the longer minute hand has any apparent connection to the rest of the clock body, with the rest appearing to hang in the air.

This is how it works: the longer minute hand is connected to the white ring, and it is in fact this ring that rotates, taking the attached minute hand with it. But how does the hour hand remain stationary while the rest turns? A concealed shaft and gear assembly takes care of that. For every full rotation of the minute hand (actually the white ring), the hour hand is only permitted a relative advancement of 1/12th of a rotation. It’s a clever system, and you can see the insides in the photo here.

Unlike clock projects that showcase their inner workings, the Hollow Clock works hard to conceal them. If you decide to make your own, [shiura] warns to expect to do a bit of tweaking to fine-tune the amount of friction between moving parts so that operation is smooth, and provides useful guidelines for doing so. Take a few minutes to watch the clock in action in the video, embedded below.

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Gaze Upon This Intricate Victorian-Era Time Lock

May 29, 2019 by Donald Papp 7 Comments

The concept of a time lock is an old one, and here you can see an example of the clockwork and gears version that kept vaults sealed against unauthorized openings. Even if the correct combination was known, these devices prevented opening until a pre-arranged amount of time had passed. The fine folks at [Industrial Alchemy] got a copy of a Yale Triple L mechanical time lock, and like other devices of its kind it required manual winding to function. Since the device as a whole was sealed against tampering, winding and setting was done with a key via the small holes in the front.

These devices were mounted on the inside of a vault door, and worked by mechanically interfacing with the lock mechanism in a variety of different ways depending on make and model. While the time lock was engaged, opening the door was prevented even if the correct combination was used. You may notice the multiple movements; this was for redundancy. The movements were interfaced in a mechanical OR arrangement, meaning that the first one to count down to zero would disengage the time lock. In the case of a malfunction, the backup movements would be responsible for preventing a total lockout — a condition as inconvenient and embarrassing as it would be costly.

Embedded below is a video that focuses on swapping movements in a time lock, but happens to also do a good job of showing off the mechanical design and components. Clockwork was the high technology of its time, and interest in it has seen something of a resurgence now that 3D printing is commonplace.

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Rotating Lithophane Box Turns With Time

April 3, 2018 by Kristina Panos 6 Comments

If you wanted to make a rotating display box, what would you use to make it spin? A servo? A stepper motor? [ChrisN219] didn’t need his to move quickly by any means, and this opened up his options to something we probably wouldn’t have thought to use: a clock movement. Specifically, the ~~hour~~ minute part of the shaft.

Rotating lithophanes of your loved ones makes for a pretty cool project, and there isn’t a whole lot to this build to make it difficult. Much of it is 3D printed, including the tube in the center that the LED strip is wrapped around. The base is just big enough to hold the clock movement and the LED strip controller, so it would fit nicely on a desk or a mantel.

This is version two of [Chris]’ lithophane box, which gave him a chance to perfect the frame and design a thicker center post to withstand the heat from the LED strip. All the files are available if you want to print your own panels and take them for a spin. Since it’s so easy to change them out, you may end up with a big pile to choose from.

Repairing Vintage Clock Movements

February 7, 2016 by Kristina Panos 3 Comments

It’s obvious that [Matthew] cares a great deal for vintage electric clocks. He is especially fond of the bedside alarm variety, which in our experience cast a warm orange glow on the numbers and emitted a faint, gentle hum. [Matthew] has written up a thorough treatment of Sunbeam movements in particular that covers identification, disassembly, cleaning, and repair.

These workhorse timepieces are cheap and fairly plentiful if you work the estate sale or thrift store circuit. Sometimes there is a bit of trouble with motor pinions disintegrating or the teeth wearing down on the nylon gears. The decades-old petroleum lubricant combined with heat from the spinning rotor can eat away at the motor pinion, causing it to crumble if disturbed.

Wishing to save some of these clocks from landfills, [Matthew] designed motor pin replacements specifically for Sunbeam electric movements, the relatively inexpensive alternative that graced many a mid-century household clock. He only had the shaft and a broken original to work with, but was able to design a sturdy acrylic replacement using this involute spur gear builder to generate a DXF file. Then it was just a matter of creating an STL file with Rhino 3D and shipping it off to Shapeways.

If you’ve ever wanted to get into clock or watch repair, this looks like a great way to get your feet wet unless you’re ready for some serious vintage watch repair. There’s no need to reinvent the pinion because [Matthew] sells them through his site. If you have a printer, the STL files await you.

A Networked Analog Clock

November 19, 2015 by Brian Benchoff 20 Comments

Even in the face of an Internet of Things grasping for a useful use case, an Internet-connected clock is actually a great idea. With a cheap WiFi module and a connection to an NTP server, any clock can become an atomic clock. [Jim] decided to experiment with the ESP8266 to turn a cheap analog clock into something that will display network time using a bunch of gears and motors.

The clock [Jim] chose for this build is an extremely cheap clock pulled right from the shelves of WalMart. This clock uses a standard quartz clock mechanism, powered by a single AA cell. The coils in these quartz movements can be easily controlled by pulsing current through them, and with a few a few transistors and diodes set up in an h-bridge, an ESP8266 is quite good at setting the time on this clock.

The software for this clock first connects to the WiFi network, then checks an NTP server for the true time. Once the ESP8266 gets the time, it starts hammering the coil in the clock movement until the hands are where they should be.

[Jim] says the project needs a bit of work – there is no feedback on the clock to determine the position of the hands. Instead, the time is just set assuming the clock hands started off at 12:00. Still, even with that small fault, it’s a great build and a great exploit of what can be done with a cheap quarts clock movement.

If you’d like to go to the opposite extreme of cost and complexity, how about a DIY retro atomic clock? Or if you’re in need of a wakeup, we’ve seen a ton of alarm clock posts in the past few weeks.