View Full Version : Clock Design

Michael Simpson Virgina
12-27-2010, 5:46 AM
After the discussion on Gearotic earlyer I thought I would share how I design my clocks. It applies to both CNC and laser clocks.

First I cut all my gears with a 1/4 hole for the shaft to start. This way they fit on standard 1/4 bolts.

I start with a platform I built. It has 400 5/16 holes spaced 1/2 on center. With the 1/4" bolt in the 5/16" hole I can mesh just about any gear or gear combination as shown here.


When I cut my gears I also cut several spacers out of the same material. I also have various 1/8" spacers that I cut with my laser.

It thakes me a couple passes working from one end to the other but I eventualy get my train working pretty good.

I also have some pointers shown here that allow me to test the ratios to make sure Im getting the correct revolutions.


This is important as on the last clock I was useing the wroing gear and after marking off my minutes and hours I caught it before I had designed my clock carcas.

This clock has a combined hour and minute gear train (big gear in center) with a seperate second hand. This is the back of the clock. The hands will be attached to the shafts in the front once the carcase is designed.


The upper most wheel is the second sweep and each gear is one second. This makes it easy to drive it with a spring and Escapement, stepper or motor.

Once gear lay it is fixed I go back to corel and remove all but the holes used and I have my cut out for my carcas.

I never make wieght driven clocks. Its very hard to build one that doesnt require winding every one or two days. Believe me no one wants to wind a clock every day. I use spring windings, motors, or other.

Since I now have a CNC and laser I can easily dublocate the designed clock in what ever material I want. This one was built out of MDF just vecause I had a bunch of 1/2" material laying around. If I were doing it with the laser I would cut 4 sheets of 1/8 stock and laminate them or just keep the clock thin if done in acrylic.

Keith Outten
12-27-2010, 9:27 AM
Very nice work Michael,

I have always said that owning both a CNC Router and a Laser Engraver is the ticket. These two machines work together well since both are precision machines and they open up a whole new world of things that can be done.

Gear projects have a very high cool factor!

Doug Griffith
12-27-2010, 11:43 AM
Great work. I'm also liking your test platform.

Paul Phillips
12-27-2010, 1:30 PM
Awesome Michael, nice work. I just bought my first Clayton Boyer design and am in the process of scanning the drawings into Corel Draw so I can try it out on the laser. I'm still trying to wrap my brain around how the whole thing works let alone be able to design my own! Can you tell us where you get your spring windings and motors?

Michael Simpson Virgina
12-27-2010, 3:32 PM
For a motor you need an ac motor that is regulated by the 60Hz AC current. This will help the clock keep greate time. While the US AC voltage will change the actual frequency is very accurate. JAmeco Electronics currently sells only one AC motor. Its 6 RPM so you would need a 10 tooth drive gear to drive a 60tooth second hand gear like in my configuration. Yours will probabaly be diffrent.

For springs I make my own out of various materials. I normal only need enough spring to keep the clock running for at least an hour. I then use a motor/stepper/servo to wind the spring as needed. If you wind on the hour you can also work some sort of chime/noise to indicate hour.

Many clock plans out there use a wieght mech on the minute hand train. This was one of the traditional designs. PRoblem is you need a lot of wieght and its a pain to wind.

Another cool method for driving the clock is to place some steel on the pendulum and have it activate a slight electro magnet during a swing. It does not take much to keep the momentum up provided the gears all run smooth.

Lee DeRaud
12-27-2010, 5:22 PM
I normal only need enough spring to keep the clock running for at least an hour. I then use a motor/stepper/servo to wind the spring as needed.(scratches head) Ok, I must be missing something obvious: if you've got a stepper motor (and associated control logic) to wind the spring, can't you just use it to drive the whole clock?

Michael Simpson Virgina
12-27-2010, 5:51 PM
Following that logic. Why not just use a digital clock. Using a motor to wind the spring lets you keep a lot of the old time charm. IE. Tick, Tock and pendumum.

It also means you adjust the clocks speed the old fashend way by adjusting the bob. I have a restored grandfauther clock that took me a week to get set correctly but its been on time for over a year. I think I gained 4 seconds.

Now thats not to say I wouldnt drive the clock direcly with a motor. This clock will be using a direct drive motor. I also have plans for a steam driven clock. IE every hour the boiler fires up and winds the clock. To let off the steam the clock will sound a light whistle.

This is what clock making is all about.

Lee DeRaud
12-27-2010, 6:04 PM
Using a motor to wind the spring lets you keep a lot of the old time charm. IE. Tick, Tock and pendumum.Fair enough...all I was seeing was gears.:p

Michael Simpson Virgina
12-27-2010, 7:07 PM
Im just about ready to work on the carcass. The biggest problem I have is the machineing of the hour shaft. Currently its diameter is 1/2" and it fits over the 1/4" minute shaft. That does not make for a very thick wood wall.

This round the the 1/2" shaft was made of 3/4" baltic birtch ply cut out on the cnc. Two of them were stacked and glued to the gear. I then placed it on a pen mandrel and took the shaft down to 1/2". I am going to try it plain first to see how smooth it works in the system. It is the final gear so it gets a lot of torque. If I have to I could use a hidden 1/2 bearing.

Dan Hintz
12-27-2010, 9:32 PM

I you want a shaft out of metal, let me know... I've been thinking of projects to finally use my metal lathe for practice.

Michael Simpson Virgina
12-27-2010, 10:19 PM
All my previous clocks in the past had Brass shafts. Very easy to pack hours, Minutes, and seconds into a set of Brass tubes. I wanted this one to be all wood.

Here is the next step in the process. Once I have the exact distances for a nice mesh for each set I create cardboard templates and lable them by the gear numbers. IE in this clock I had the templates 2-3, 4-5, 6-7. I did not need a 8-9 as its the same as 6-7 as its a link back to the same shaft.

Once you have the distances its now a woodworking project.


In this case I just placed the templates on a piece of scrap particle board and cut out around the marks. I then drilled 1/4" holes for all but the main shaft. That one is 1/2"

This is just a prototype and I wont use it for an actual clock as its just too modern for me. Fot this type design you would be better doing acrylic gears with the laser. I could emagin the body painted white with black acrylic gears. It would also be very slim so it could be wall mounted.

If you look you can see a small AC motor next to the clock. I will mount it to the back plate once its been designed.

Here is the motor.


Here is the prototype with a small syncr motor attached.


Michael Simpson Virgina
12-31-2010, 6:36 AM
Just to finish this thread I finished the prototype clock. The prototype turned out so well I finished it and added a motor.


The funny thing is I spent more time painting the parts then I did in the design and building of the clock.


If you are interesed in how I finished it and the materials I posted more detail in the woodworking forum here (http://www.sawmillcreek.org/showthread.php?155987-New-Tools-New-Projects)

Frank Corker
12-31-2010, 8:24 AM
Mike that is a beautiful piece of work. You really have done a cracking job on it, you should be very proud of yourself. What do you intend doing with it? I'm sure you won't have any problems finding a buyer.

Michael Simpson Virgina
12-31-2010, 9:26 AM
I wouldnt sell this one as it has a few issues.

First the motor needs replacement. Its a motor from a microwave turntable. When turned on it goes in one direction. If it is turned off then back on it goes in the opposite direction. It switches each time its turned on. Also it makes too much noise. I have a new motor on order.

I need to perfect my base attachement system. I am using little round clips I created with the laser. Basicly they are a round disk with a hole in the middle and a slit down one side. They work ok but if I were to sell the clock I think I need a better system.

On the next clock I will replace the shafts with brass. The problem with dowles is they are not consistant in thickness and I dont want to have to turn my own. Also with brass shafts and spacers I can use small pins to secure things better.

I also want to integrate a second hand. I can do this in two ways.

Ring around the face that rotates
A small glass window in the lower oval hole and an extra wheel that is indexed with second ticks.