When the “glow in the dark” clock was finished it realized that I could relatively easily start another clock project. An idea I’ve had in my mind for many years… the linear clock. Now a linear clock is nothing new, but making it as simple as possible THAT is the main idea I had. So knowing how to get time from an NTP server and knowinghow to make MDF look pretty I decided it was time to start this project and really finish it as quickly as possible. Because the “glow in the dark” clock has took me over 3 years, I did not want to repeat that.

So, full of motivation, having the technology and skills… I took of on my bicycle on a trip to the local hardware store. I returned with some MDF an M6 thereaded rod and some pieces of 4mm thick and 1meter long brass rods. Now the project was started…

The linear clock I made is very simple in mechanical design but yet very effective in creating a very different kind of clock that is very easy to read.
At the bottom of this page there is a download section where you can find the sourcecode of the project, the 3D files and a detailed manual describing how to use the linear clock.

Why a linear clock and how it works:
Well the term linear might be confusing to some, because time is linear to begin with. But what linear means here is that the indicator of the clock moves in a line and not in circles.
When you search the internet for a linear clock you see all sorts of devices where time is shown by moving numbers along a line, flickering LED’s along a line and even versions where the hours are printed on a band that moves very slowly from left to right. What I wanted to make was a clock where all the hours of the day were visible all of the time. So that the indicator of the clock has a unique position on the timescale at any moment in time. In other words, the indicator is moving along the day, so loooking at the indicator you instantly know your position in the day, so see how many time is passed and how many time is left. I could have made a clock with a huger strip of LED’s to achieve the same effect, but I wanted a more old-skool looking kind of clock. A real pointer and real moving parts. And by using a stepper motor and a piece of M6 threaded rod this could be achieved very cheap and very easily, so other can make it too without having to break the bank. The fun with my system is that the scale is devided into AM and PM. The indicator of the clock moves up in the morning (AM=left side of the scale) and moves down at that afternoon (PM=right side of the scale). And by doing so the clocks indicator follows the same path as the sun across our sky. Well… in theory, because of the fact we have timezones and DST. Meaning that our local time doesn’t always honour the true definition of 12:00, which would be at the moment of the sun at the highest point in the sky. But this is just a minor a detail. This makes this kind of clock very suitable to small children, as you could place notes along the timescale like (get up, breakfast, school, lunch, diner, etc). But it could very well be an aid for authistic people, because they have sometimes a very hard time in using clocks. Telling time may seem like a simple task for many of us, to some it simply doens’t make sense why time is divided in 2 circles of 12 hours with smaller circles underneath deviding those hours into 60 steps of a minute. When I come to think of it, although I understand how clocks evolved, I have difficulties accepting why I ever caught on. But that was mostlikely because there wasn’t anyting better. Anyway the linear clock has one huge advantage… it’s huge. You can’t make a wrist watch using the same design without loosing accuracy.

In my clock I chose to have a distance between the hours of 60mm, therefore every minute the indicator travels 1mm, which for an M6 threaded rod is exactly rotation (how convenient).
The indicator is driven by one single stepper motor, it turns left or it turns right. Now how does the indicator change from the leftside of the scale to the right side of the scale when you have only one motor, you might ask. Well that is in fact very simple, although the nut inside the indicator has very little friction with the threaded rod, it is certainly not zero. Therefor when the indicator moves down the rod has to turn counter clockwise, because of the friction ,the indicator also moves counter clockwise untill it can move no further, so when it moves down it rides along the PM side of the scale. And when the indicator moves up the rod has to turn clockwise and because of the friction the indicator also moves clockwise untill it can move no further, so when it moves up it rides along the AM side of the scale. This way you see the indicator turn at noon and mignight from left to right and vice versa. It cannot be more simple than that, or can it? There is one catch the clock always has to be in a vertical position. Because if the clock was to be placed horizontally against the wall, then the weight of the indicator would always make it point downwards. No you could increase the friction with the threaded rod, but that would also result in much more wear on the parts, a thing that should be avoided if you want to make something that should works for a long time. So by having the clock placed vertically against the wal, the weight of the indicator is not having any effect and the clock can mooth smoothly without problems.”

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