Thursday, April 17, 2014

The Conical Pendulum Wooden Clock Part 6

The conical clock fully functional!


Images tell more than million words Sonrisa

  • New pendulum support arc design: more stable and stronger
  • New bevel gear design: Allows more play and wood imperfections, runs smoother than the original design
  • Speed control plate
  • Elliptical clock dial
  • Elliptical clock hands

Still missing:

  • Lower decorative arc
  • wheel stoppers
  • wood finishing
  • brass pendulum polishing

I am really proud and happy with this project and I imagine the Clyton Boyer will enjoy the implementation of his basic idea that was draft paper few months ago. I hope I was able to intemperate and visualize his concept by making it a real clock using a new driving technology. As far as I know this is the first Conical Wooden Clock! 

In few days I will go back to the hospital for a second surgery (this one is to bring me back to normal conditions by removing  an ostomy bag and fix some abdominal issues) so I will be out of my garage for some time.

Update 4/18/2014:

Clyton Boyer email:

After Clyton saw this post he wrote to me:

“…SO Excellent, Carlos.  Yes, I believe it is the only wooden conical also.  I have seen a lot of conicals, and I've been to many clock museums or museums with clocks, and I've never seen my dream of a wooden conical realized...until NOW! and I love it.  I am so happy that you took on this design and added your ingenuity to it and helped to create my dream (and apparently YOUR dream, as well).

I really like the way it looks and all of the personalizations that you have added to it, like the oval dial, the bevel gears, and many other smaller changes (and of course, your very own self-created motor!!!  That's no small task!)

The conical design really looks so beautiful and there is so much action.  I truly appreciate your dedication and what you have done to create the conical in real life.  It's a beauty.

Good luck with your second surgery.  Hopefully all goes very well and you will be up and back in the shop very soon.

Thanks for keeping me informed on your project.  It is so much fun!…”

And in a previous mail when I was sharing with him the first tests he wrote:

“…The motor-driven conical pendulum clock that you have built is truly wonderful.  I showed all the vids to my wife.  She has given you build a "Two Thumbs Up!" approval, and thinks it looks "really neat!"

I have to agree.  I've always liked that design, and have always been tempted to build it, but now that I see it in action, I'm even more motivated.  I'm glad it worked well with the motor you designed to drive it.  I would, of course, drive mine with rocks...paleolithic style.  Ha.  Or this might also be a nice constant force spring-driven design in a tabletop version.  But as you mention, conical pendulums have an inherently inaccuracy in their design, and none would be anywhere near as accurate as your motor driven version.

It is SO lovely to see a vision that I only had in my head come to life!  Thank you for your passion on this project.  It is wonderful to share with other builders that share the same passions.

Beautifully done, Carlos!!!…”


I only have to say to Clyton:

Thank you very much for introducing me to this amazing hobby! This has been the most amazing and pleasure providing creative activity I have ever performed. My brain is exploding with ideas and new projects. I never thought that there were so many  artistic and creative neurons active in my brain. 

The Mechanical Speed Control for the Conical Pendulum

There is a basic difference between the classic pendulum and the conical pendulum:


In the classic pendulum and for small swings the period of swing is approximately the same for different size swings: that is, the period is independent of amplitude. This property, called isochronism, is the reason pendulums are so useful for timekeeping. Successive swings of the pendulum, even if changing in amplitude, take the same amount of time. The basic formula for the ideal pendulum is:


So for small swing angles (much less than 1 radian (57 degrees) the period of the oscillation will depend basically of the length on the pendulum.

In the conical pendulum: the period of rotation for small angles θ is determined by the length of the pendulum.


The formulas for the conical pendulum are:


Where t is the period of revolution

This formula can be expressed as:


When applying a force to keep the pendulum rotating, there will be a centrifugal force that will increase the angle θ so h will be smaller as the angle increases and the period of revolution will be smaller. In theory for small forces there will be equilibrium and the angle and the speed will be constant (for small angles).

In real life and with imperfect arbors and wood susceptible for changes by temperature and humidity the equilibrium point will constantly change. Sometimes, when the friction is low the pendulum will rotate faster  (larger angle) and when there is more friction the speed will be slower (smaller angle) because we are applying a constant rotation torque with the impulse motor.

The above means that the conical pendulum is intrinsically inaccurate for time keeping unless we add some kind of regulation and this has been the challenge for all conical pendulum clock designs since they were invented. The patent of J. C. Briggs in 1885 is related to a speed control device that increases the friction as the angle of the pendulum grows. But in reality this is basically what the Watt’s speed governor does.

My challenge was to find a way to make a very simple speed control for my conical clock and I did it!

I added a small piece of wood cut in a parabolic shape. The pendulum rod’s tip will hit the piece of wood when the angle increases due to speed and this will force a reduction of the angle and will slow down the rotation speed.


In the flowing slow motion video (1/8th of the real speed where on revolution is 8 seconds) you can see how this device works and slows down the pendulum speed.


Thursday, April 3, 2014

The Conical Pendulum Wooden Clock Part 5

Las few days in the garage were 100% dedicated to mill the wheel and pinions of the clock train and today I finished and mounted all of them with their arbors in the frame.

The clock looks really beautiful RelojSonrisa

2014-04-03 16.56.56


2014-04-03 16.57.46

I still need to glue the pinions and wheels to the support , also polish the arbors to minimize friction and make the stoppers for the wheels.

Next step is to make a provisional vertical support (The clock is a wall mounted clock), fix the clock to that provisional wall, install the pendulum and start testing.